MongoDB Lens

by furey
Verified
JavaScript
MIT License
796
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mongodb-lens
#!/usr/bin/env node

import { McpServer, ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js'
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
import stripJsonComments from 'strip-json-comments'
import { readFileSync, existsSync } from 'fs'
import { dirname, join } from 'path'
import { fileURLToPath } from 'url'
import { Transform } from 'stream'
import mongodb from 'mongodb'
import { z } from 'zod'
import _ from 'lodash'

const { MongoClient, ObjectId, GridFSBucket } = mongodb
const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)

const start = async (mongoUri) => {
  log(`MongoDB Lens v${getPackageVersion()} starting…`, true)

  mongoUriCurrent = mongoUri
  mongoUriOriginal = mongoUri

  const connected = await connect(mongoUri)
  if (!connected) return log('Failed to connect to MongoDB database.', true) || false

  log('Starting watchdog…')
  startWatchdog()

  await setProfilerSlowMs()

  log('Initializing MCP server…')
  server = new McpServer({
    name: 'MongoDB Lens',
    version: getPackageVersion(),
    description: 'MongoDB MCP server for natural language database interaction',
    homepage: 'https://github.com/furey/mongodb-lens',
    license: 'MIT',
    vendor: {
      name: 'James Furey',
      url: 'https://about.me/jamesfurey'
    }
  }, {
    instructions
  })

  server.fallbackRequestHandler = async request => {
    log(`Received request for undefined method: ${request.method}`, true)
    const error = new Error(`Method '${request.method}' not found`)
    error.code = JSONRPC_ERROR_CODES.METHOD_NOT_FOUND
    throw error
  }

  log('Registering MCP resources…')
  registerResources(server)

  log('Registering MCP prompts…')
  registerPrompts(server)

  log('Registering MCP tools…')
  registerTools(server)

  log('Creating stdio transport…')
  transport = new StdioServerTransport()

  log('Connecting MCP server transport…')
  await server.connect(transport)

  log('MongoDB Lens server running.', true)
  return true
}

const connect = async (uri = 'mongodb://localhost:27017', validate = true) => {
  try {
    log(`Connecting to MongoDB at: ${obfuscateMongoUri(uri)}`)

    const connectionOptions = { ...config.connectionOptions }

    mongoClient = new MongoClient(uri, connectionOptions)

    let retryCount = 0
    const maxRetries = config.connection.maxRetries

    while (retryCount < maxRetries) {
      try {
        await mongoClient.connect()
        break
      } catch (connectionError) {
        retryCount++
        if (retryCount >= maxRetries) throw connectionError
        const delay = Math.min(config.connection.initialRetryDelayMs * Math.pow(2, retryCount), config.connection.maxRetryDelayMs)
        log(`Connection attempt ${retryCount} failed, retrying in ${delay/1000} seconds…`)
        await new Promise(resolve => setTimeout(resolve, delay))
      }
    }

    if (validate) {
      try {
        const adminDb = mongoClient.db('admin')
        const serverInfo = await adminDb.command({ buildInfo: 1 })
        log(`Connected to MongoDB server version: ${serverInfo.version}`)

        const cacheKey = 'server_info'
        memoryCache.serverStatus.set(cacheKey, {
          data: serverInfo,
          timestamp: Date.now()
        })
      } catch (infoError) {
        log(`Warning: Unable to get server info: ${infoError.message}`)
      }
    }

    currentDbName = extractDbNameFromConnectionString(uri)
    currentDb = mongoClient.db(currentDbName)

    if (validate) {
      try {
        await currentDb.stats()
      } catch (statsError) {
        log(`Warning: Unable to get database stats: ${statsError.message}`)
      }
    }

    mongoClient.on('error', err => {
      log(`MongoDB connection error: ${err.message}. Will attempt to reconnect.`, true)
    })

    mongoClient.on('close', () => {
      if (!isShuttingDown) {
        log('MongoDB connection closed. Will attempt to reconnect.', true)
      } else {
        log('MongoDB connection closed during shutdown.')
      }
    })

    log(`Connected to MongoDB successfully, using database: ${currentDbName}`)
    mongoUriCurrent = uri
    return true
  } catch (error) {
    log(`MongoDB connection error: ${error.message}`, true)
    return false
  }
}

const startWatchdog = () => {
  if (watchdog) clearInterval(watchdog)

  watchdog = setInterval(() => {
    const memoryUsage = process.memoryUsage()
    const heapUsedMB = Math.round(memoryUsage.heapUsed / 1024 / 1024)
    const heapTotalMB = Math.round(memoryUsage.heapTotal / 1024 / 1024)

    if (heapUsedMB > config.memory.warningThresholdMB) {
      log(`High memory usage: ${heapUsedMB}MB used of ${heapTotalMB}MB heap`, true)

      if (heapUsedMB > config.memory.criticalThresholdMB) {
        log('Critical memory pressure. Clearing caches…', true)
        config.enabledCaches.forEach(cache => {
          if (memoryCache[cache]) memoryCache[cache].clear()
        })
        if (config.memory.enableGC && global.gc) {
          global.gc()
        } else if (config.memory.enableGC) {
          log('Garbage collection requested but not available. Run Node.js with --expose-gc flag.', true)
        }
      }
    }

    const isClientConnected = mongoClient && mongoClient.topology && mongoClient.topology.isConnected()
    if (!isClientConnected && !isChangingConnection) {
      log('Detected MongoDB disconnection. Attempting reconnect…', true)
      reconnect()
    }
  }, config.watchdogIntervalMs)
}

const reconnect = async () => {
  if (connectionRetries > config.connection.reconnectionRetries) {
    log('Maximum reconnection attempts reached. Giving up.', true)
    return false
  }

  connectionRetries++
  log(`Reconnection attempt ${connectionRetries}…`, true)

  try {
    await mongoClient.connect()
    log('Reconnected to MongoDB successfully', true)
    connectionRetries = 0
    return true
  } catch (error) {
    log(`Reconnection failed: ${error.message}`, true)
    return false
  }
}

const extractDbNameFromConnectionString = (uri) => {
  const pathParts = uri.split('/').filter(part => part)
  const lastPart = pathParts[pathParts.length - 1]?.split('?')[0]
  currentDbName = (lastPart && !lastPart.includes(':')) ? lastPart : config.defaultDbName
  return currentDbName
}

const resolveMongoUri = (uriOrAlias) => {
  if (uriOrAlias.includes('://') || uriOrAlias.includes('@')) {
    return uriOrAlias
  }

  const uri = mongoUriMap.get(uriOrAlias.toLowerCase())
  if (uri) {
    mongoUriAlias = uriOrAlias
    log(`Resolved alias "${uriOrAlias}" to URI: ${uri}`)
    return uri
  }

  throw new Error(`"${uriOrAlias}" is not a valid MongoDB URI or connection alias.`)
}

const obfuscateMongoUri = (uri) => {
  if (!uri || typeof uri !== 'string') return uri
  try {
    if (uri.includes('@') && uri.includes('://')) {
      const parts = uri.split('@')
      const authPart = parts[0]
      const restPart = parts.slice(1).join('@')
      const authIndex = authPart.lastIndexOf('://')
      if (authIndex !== -1) {
        const protocol = authPart.substring(0, authIndex + 3)
        const credentials = authPart.substring(authIndex + 3)
        if (credentials.includes(':')) {
          const [username, ...passwordParts] = credentials.split(':')
          return `${protocol}${username}:********@${restPart}`
        }
      }
    }
    return uri
  } catch (error) {
    log(`Error obfuscating URI: ${error.message}`, true)
    return uri
  }
}

const changeConnection = async (uri, validate = true) => {
  isChangingConnection = true

  try {
    if (mongoClient) await mongoClient.close()
    clearMemoryCache()
    const resolvedUri = resolveMongoUri(uri)
    const connected = await connect(resolvedUri, validate)
    isChangingConnection = false
    if (!connected) throw new Error(`Failed to connect to MongoDB at URI: ${obfuscateMongoUri(resolvedUri)}`)
    return true
  } catch (error) {
    isChangingConnection = false
    throw error
  }
}

const isDisabled = (type, name) => {
  if (!config.disabled || !config.disabled[type]) return false
  if (config.disabled[type] === true) return true
  return Array.isArray(config.disabled[type]) && config.disabled[type].includes(name)
}

const registerResources = (server) => {
  if (isDisabled('resources', true)) {
    log('All MCP resources disabled via configuration', true)
    return
  }

  if (!isDisabled('resources', 'databases')) {
    server.resource(
      'databases',
      'mongodb://databases',
      { description: 'List of all accessible MongoDB databases' },
      async () => {
        log('Resource: Retrieving list of databases…')
        const dbs = await listDatabases()
        log(`Resource: Found ${dbs.length} databases.`)
        return {
          contents: [{
            uri: 'mongodb://databases',
            text: formatDatabasesList(dbs)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'database-users')) {
    server.resource(
      'database-users',
      'mongodb://database/users',
      { description: 'MongoDB database users and roles' },
      async () => {
        log('Resource: Retrieving database users…')
        const users = await getDatabaseUsers()
        log(`Resource: Retrieved user information.`)
        return {
          contents: [{
            uri: 'mongodb://database/users',
            text: formatDatabaseUsers(users)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'database-triggers')) {
    server.resource(
      'database-triggers',
      'mongodb://database/triggers',
      { description: 'Database change streams and event triggers configuration' },
      async () => {
        log('Resource: Retrieving database triggers and event configuration…')
        const triggers = await getDatabaseTriggers()
        return {
          contents: [{
            uri: 'mongodb://database/triggers',
            text: formatTriggerConfiguration(triggers)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'stored-functions')) {
    server.resource(
      'stored-functions',
      'mongodb://database/functions',
      { description: 'MongoDB stored JavaScript functions' },
      async () => {
        log('Resource: Retrieving stored JavaScript functions…')
        const functions = await getStoredFunctions()
        log(`Resource: Retrieved stored functions.`)
        return {
          contents: [{
            uri: 'mongodb://database/functions',
            text: formatStoredFunctions(functions)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'collections')) {
    server.resource(
      'collections',
      'mongodb://collections',
      { description: 'List of collections in the current database' },
      async () => {
        log(`Resource: Retrieving collections from database '${currentDbName}'…`)
        const collections = await listCollections()
        log(`Resource: Found ${collections.length} collections.`)
        return {
          contents: [{
            uri: 'mongodb://collections',
            text: formatCollectionsList(collections)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'collection-indexes')) {
    server.resource(
      'collection-indexes',
      new ResourceTemplate('mongodb://collection/{name}/indexes', {
        list: async () => {
          try {
            log('Resource: Listing collection indexes resources…')
            const collections = await listCollections()
            log(`Resource: Preparing index resources for ${collections.length} collections.`)
            return {
              resources: collections.map(coll => ({
                uri: `mongodb://collection/${coll.name}/indexes`,
                name: `${coll.name} Indexes`,
                description: `Indexes for ${coll.name} collection`
              }))
            }
          } catch (error) {
            log(`Error listing collections for indexes: ${error.message}`, true)
            return { resources: [] }
          }
        },
        complete: {
          name: async (value) => {
            try {
              log(`Resource: Autocompleting collection name for indexes with prefix '${value}'…`)
              const collections = await listCollections()
              const matches = collections
                .map(coll => coll.name)
                .filter(name => name.toLowerCase().includes(value.toLowerCase()))
              log(`Resource: Found ${matches.length} matching collections for indexes.`)
              return matches
            } catch (error) {
              log(`Error completing collection names: ${error.message}`, true)
              return []
            }
          }
        }
      }),
      { description: 'Index information for a MongoDB collection' },
      async (uri, { name }) => {
        log(`Resource: Retrieving indexes for collection '${name}'…`)
        const indexes = await getCollectionIndexes(name)
        log(`Resource: Retrieved ${indexes.length} indexes for collection '${name}'.`)
        return {
          contents: [{
            uri: uri.href,
            text: formatIndexes(indexes)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'collection-schema')) {
    server.resource(
      'collection-schema',
      new ResourceTemplate('mongodb://collection/{name}/schema', {
        list: async () => {
          try {
            log('Resource: Listing collection schemas…')
            const collections = await listCollections()
            log(`Resource: Preparing schema resources for ${collections.length} collections.`)
            return {
              resources: collections.map(coll => ({
                uri: `mongodb://collection/${coll.name}/schema`,
                name: `${coll.name} Schema`,
                description: `Schema for ${coll.name} collection`
              }))
            }
          } catch (error) {
            log(`Error listing collection schemas: ${error.message}`, true)
            return { resources: [] }
          }
        },
        complete: {
          name: async (value) => {
            try {
              log(`Resource: Autocompleting collection name with prefix '${value}'…`)
              const collections = await listCollections()
              const matches = collections
                .map(coll => coll.name)
                .filter(name => name.toLowerCase().includes(value.toLowerCase()))
              log(`Resource: Found ${matches.length} matching collections.`)
              return matches
            } catch (error) {
              log(`Error completing collection names: ${error.message}`, true)
              return []
            }
          },
          field: async (value, params) => {
            try {
              if (!params.name) return []

              log(`Resource: Autocompleting field name with prefix '${value}' for collection '${params.name}'…`)
              const fields = await getCollectionFields(params.name)
              const matches = fields.filter(field =>
                field.toLowerCase().includes(value.toLowerCase())
              )
              log(`Resource: Found ${matches.length} matching fields for collection '${params.name}'.`)
              return matches
            } catch (error) {
              log(`Error completing field names: ${error.message}`, true)
              return []
            }
          }
        }
      }),
      { description: 'Schema information for a MongoDB collection' },
      async (uri, { name }) => {
        log(`Resource: Inferring schema for collection '${name}'…`)
        const schema = await inferSchema(name)
        log(`Resource: Schema inference complete for '${name}', identified ${Object.keys(schema.fields).length} fields.`)
        return {
          contents: [{
            uri: uri.href,
            text: formatSchema(schema)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'collection-stats')) {
    server.resource(
      'collection-stats',
      new ResourceTemplate('mongodb://collection/{name}/stats', {
        list: async () => {
          try {
            log('Resource: Listing collection stats resources…')
            const collections = await listCollections()
            log(`Resource: Preparing stats resources for ${collections.length} collections.`)
            return {
              resources: collections.map(coll => ({
                uri: `mongodb://collection/${coll.name}/stats`,
                name: `${coll.name} Stats`,
                description: `Statistics for ${coll.name} collection`
              }))
            }
          } catch (error) {
            log(`Error listing collections for stats: ${error.message}`, true)
            return { resources: [] }
          }
        },
        complete: {
          name: async (value) => {
            try {
              log(`Resource: Autocompleting collection name for stats with prefix '${value}'…`)
              const collections = await listCollections()
              const matches = collections
                .map(coll => coll.name)
                .filter(name => name.toLowerCase().includes(value.toLowerCase()))
              log(`Resource: Found ${matches.length} matching collections for stats.`)
              return matches
            } catch (error) {
              log(`Error completing collection names: ${error.message}`, true)
              return []
            }
          }
        }
      }),
      { description: 'Performance statistics for a MongoDB collection' },
      async (uri, { name }) => {
        log(`Resource: Retrieving stats for collection '${name}'…`)
        const stats = await getCollectionStats(name)
        log(`Resource: Retrieved stats for collection '${name}'.`)
        return {
          contents: [{
            uri: uri.href,
            text: formatStats(stats)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'collection-validation')) {
    server.resource(
      'collection-validation',
      new ResourceTemplate('mongodb://collection/{name}/validation', {
        list: async () => {
          try {
            log('Resource: Listing collection validation resources…')
            const collections = await listCollections()
            log(`Resource: Preparing validation resources for ${collections.length} collections.`)
            return {
              resources: collections.map(coll => ({
                uri: `mongodb://collection/${coll.name}/validation`,
                name: `${coll.name} Validation`,
                description: `Validation rules for ${coll.name} collection`
              }))
            }
          } catch (error) {
            log(`Error listing collections for validation: ${error.message}`, true)
            return { resources: [] }
          }
        },
        complete: {
          name: async (value) => {
            try {
              log(`Resource: Autocompleting collection name for validation with prefix '${value}'…`)
              const collections = await listCollections()
              const matches = collections
                .map(coll => coll.name)
                .filter(name => name.toLowerCase().includes(value.toLowerCase()))
              return matches
            } catch (error) {
              log(`Error completing collection names: ${error.message}`, true)
              return []
            }
          }
        }
      }),
      { description: 'Validation rules for a MongoDB collection' },
      async (uri, { name }) => {
        log(`Resource: Retrieving validation rules for collection '${name}'…`)
        const validation = await getCollectionValidation(name)
        log(`Resource: Retrieved validation rules for collection '${name}'.`)
        return {
          contents: [{
            uri: uri.href,
            text: formatValidationRules(validation)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'server-status')) {
    server.resource(
      'server-status',
      'mongodb://server/status',
      { description: 'MongoDB server status information' },
      async () => {
        log('Resource: Retrieving server status…')
        const status = await getServerStatus()
        log('Resource: Retrieved server status information.')
        return {
          contents: [{
            uri: 'mongodb://server/status',
            text: formatServerStatus(status)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'replica-status')) {
    server.resource(
      'replica-status',
      'mongodb://server/replica',
      { description: 'MongoDB replica set status and configuration' },
      async () => {
        log('Resource: Retrieving replica set status…')
        const status = await getReplicaSetStatus()
        log('Resource: Retrieved replica set status information.')
        return {
          contents: [{
            uri: 'mongodb://server/replica',
            text: formatReplicaSetStatus(status)
          }]
        }
      }
    )
  }

  if (!isDisabled('resources', 'performance-metrics')) {
    server.resource(
      'performance-metrics',
      'mongodb://server/metrics',
      { description: 'Real-time MongoDB performance metrics and profiling data' },
      async () => {
        log('Resource: Retrieving performance metrics…')
        const metrics = await getPerformanceMetrics()
        return {
          contents: [{
            uri: 'mongodb://server/metrics',
            text: formatPerformanceMetrics(metrics)
          }]
        }
      }
    )
  }

  const totalRegisteredResources =
    Object.keys(server._registeredResources).length +
    Object.keys(server._registeredResourceTemplates).length
  log(`Total MCP resources: ${totalRegisteredResources}`)
}

const registerPrompts = (server) => {
  if (isDisabled('prompts', true)) {
    log('All MCP prompts disabled via configuration', true)
    return
  }

  if (!isDisabled('prompts', 'query-builder')) {
    server.prompt(
      'query-builder',
      'Help construct MongoDB query filters',
      {
        collection: z.string().min(1).describe('Collection name to query'),
        condition: z.string().describe('Describe the condition in natural language (e.g. "users older than 30")')
      },
      async ({ collection, condition }) => {
        log(`Prompt: Initializing [query-builder] for collection '${collection}' with condition: "${condition}".`)

        const fields = await getCollectionFields(collection)
        const fieldInfo = fields.length > 0 ? `\nAvailable fields: ${fields.join(', ')}` : ''

        return {
          description: `MongoDB Query Builder for ${collection}`,
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please help me create a MongoDB query for the '${collection}' collection based on this condition: "${condition}".

    I need both the filter object and a complete example showing how to use it with the findDocuments tool.

    Guidelines:
    1. Create a valid MongoDB query filter as a JSON object
    2. Show me how special MongoDB operators work if needed (like $gt, $in, etc.)
    3. Provide a complete example of using this with the findDocuments tool
    4. Suggest any relevant projections or sort options
    ${fieldInfo}

    Remember: I'm working with the ${currentDbName} database and the ${collection} collection.`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'aggregation-builder')) {
    server.prompt(
      'aggregation-builder',
      'Help construct MongoDB aggregation pipelines',
      {
        collection: z.string().min(1).describe('Collection name for aggregation'),
        goal: z.string().describe('What you want to calculate or analyze')
      },
      ({ collection, goal }) => {
        log(`Prompt: Initializing [aggregation-builder] for collection '${collection}' with goal: "${goal}".`)
        return {
          description: `MongoDB Aggregation Pipeline Builder for ${collection}`,
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need to create a MongoDB aggregation pipeline for the '${collection}' collection to ${goal}.

  Please help me create:
  1. A complete aggregation pipeline as a JSON array
  2. An explanation of each stage in the pipeline
  3. How to execute this with the aggregateData tool

  Remember: I'm working with the ${currentDbName} database and the ${collection} collection.`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'schema-analysis')) {
    server.prompt(
      'schema-analysis',
      'Analyze collection schema and recommend improvements',
      {
        collection: z.string().min(1).describe('Collection name to analyze')
      },
      async ({ collection }) => {
        log(`Prompt: Initializing [schema-analysis] for collection '${collection}'…`)
        const schema = await inferSchema(collection)
        log(`Prompt: Retrieved schema for '${collection}' with ${Object.keys(schema.fields).length} fields.`)
        return {
          description: `MongoDB Schema Analysis for ${collection}`,
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please analyze the schema of the '${collection}' collection and provide recommendations:

  Here's the current schema:
  ${formatSchema(schema)}

  Could you help with:
  1. Identifying any schema design issues or inconsistencies
  2. Suggesting schema improvements for better performance
  3. Recommending appropriate indexes based on the data structure
  4. Best practices for this type of data model
  5. Any potential MongoDB-specific optimizations`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'index-recommendation')) {
    server.prompt(
      'index-recommendation',
      'Get index recommendations for query patterns',
      {
        collection: z.string().min(1).describe('Collection name'),
        queryPattern: z.string().describe('Common query pattern or operation')
      },
      ({ collection, queryPattern }) => {
        log(`Prompt: Initializing [index-recommendation] for collection '${collection}' with query pattern: "${queryPattern}".`)
        return {
          description: `MongoDB Index Recommendations for ${collection}`,
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need index recommendations for the '${collection}' collection to optimize this query pattern: "${queryPattern}".

  Please provide:
  1. Recommended index(es) with proper key specification
  2. Explanation of why this index would help
  3. The exact command to create this index using the createIndex tool
  4. How to verify the index is being used
  5. Any potential trade-offs or considerations for this index

  Remember: I'm working with the ${currentDbName} database and the ${collection} collection.`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'mongo-shell')) {
    server.prompt(
      'mongo-shell',
      'Generate MongoDB shell commands',
      {
        operation: z.string().describe('Operation you want to perform'),
        details: z.string().optional().describe('Additional details about the operation')
      },
      ({ operation, details }) => {
        log(`Prompt: Initializing [mongo-shell] for operation: "${operation}" with${details ? ' details: "' + details + '"' : 'out details'}.`)
        return {
          description: 'MongoDB Shell Command Generator',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please generate MongoDB shell commands to ${operation}${details ? ` with these details: ${details}` : ''}.

  I need:
  1. The exact MongoDB shell command(s)
  2. Explanation of each part of the command
  3. How this translates to using MongoDB Lens tools
  4. Any important considerations or variations

  Current database: ${currentDbName}`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'data-modeling')) {
    server.prompt(
      'data-modeling',
      'Get MongoDB data modeling advice for specific use cases',
      {
        useCase: z.string().describe('Describe your application or data use case'),
        requirements: z.string().describe('Key requirements (performance, access patterns, etc.)'),
        existingData: z.string().optional().describe('Optional: describe any existing data structure')
      },
      ({ useCase, requirements, existingData }) => {
        log(`Prompt: Initializing [data-modeling] for use case: "${useCase}".`)
        return {
          description: 'MongoDB Data Modeling Guide',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need help designing a MongoDB data model for this use case: "${useCase}".

  Key requirements:
  ${requirements}

  ${existingData ? `Existing data structure:\n${existingData}\n\n` : ''}
  Please provide:
  1. Recommended data model with collection structures
  2. Sample document structures in JSON format
  3. Explanation of design decisions and trade-offs
  4. Appropriate indexing strategy
  5. Any MongoDB-specific features or patterns I should consider
  6. How this model addresses the stated requirements`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'query-optimizer')) {
    server.prompt(
      'query-optimizer',
      'Get optimization advice for slow queries',
      {
        collection: z.string().min(1).describe('Collection name'),
        query: z.string().describe('The slow query (as a JSON filter)'),
        performance: z.string().optional().describe('Optional: current performance metrics')
      },
      async ({ collection, query, performance }) => {
        log(`Prompt: Initializing [query-optimizer] for collection '${collection}' with query: ${query}.`)
        const stats = await getCollectionStats(collection)
        const indexes = await getCollectionIndexes(collection)
        return {
          description: 'MongoDB Query Optimization Advisor',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I have a slow MongoDB query on the '${collection}' collection and need help optimizing it.

  Query filter: ${query}

  ${performance ? `Current performance: ${performance}\n\n` : ''}
  Collection stats:
  ${formatStats(stats)}

  Current indexes:
  ${formatIndexes(indexes)}

  Please provide:
  1. Analysis of why this query might be slow
  2. Recommend index changes (additions or modifications)
  3. Suggest query structure improvements
  4. Explain how to verify performance improvements
  5. Other optimization techniques I should consider`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'security-audit')) {
    server.prompt(
      'security-audit',
      'Get MongoDB security recommendations',
      {},
      async () => {
        log('Prompt: Initializing [security-audit].')
        const serverStatus = await getServerStatus()
        const users = await getDatabaseUsers()
        return {
          description: 'MongoDB Security Audit',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please help me perform a security audit on my MongoDB deployment.

  Server information:
  ${formatServerStatus(serverStatus)}

  User information:
  ${formatDatabaseUsers(users)}

  Please provide:
  1. Potential security vulnerabilities in my current setup
  2. Recommendations for improving security
  3. Authentication and authorization best practices
  4. Network security considerations
  5. Data encryption options
  6. Audit logging recommendations
  7. Backup security considerations`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'backup-strategy')) {
    server.prompt(
      'backup-strategy',
      'Get advice on MongoDB backup and recovery approaches',
      {
        databaseSize: z.string().optional().describe('Optional: database size information'),
        uptime: z.string().optional().describe('Optional: uptime requirements (e.g. "99.9%")'),
        rpo: z.string().optional().describe('Optional: recovery point objective'),
        rto: z.string().optional().describe('Optional: recovery time objective')
      },
      ({ databaseSize, uptime, rpo, rto }) => {
        log('Prompt: Initializing [backup-strategy].')
        return {
          description: 'MongoDB Backup & Recovery Strategy',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need recommendations for a MongoDB backup and recovery strategy.

  ${databaseSize ? `Database size: ${databaseSize}\n` : ''}${uptime ? `Uptime requirement: ${uptime}\n` : ''}${rpo ? `Recovery Point Objective (RPO): ${rpo}\n` : ''}${rto ? `Recovery Time Objective (RTO): ${rto}\n` : ''}
  Current database: ${currentDbName}

  Please provide:
  1. Recommended backup methods for my scenario
  2. Backup frequency and retention recommendations
  3. Storage considerations and best practices
  4. Restoration procedures and testing strategy
  5. Monitoring and validation approaches
  6. High availability considerations
  7. Tools and commands for implementing the strategy`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'migration-guide')) {
    server.prompt(
      'migration-guide',
      'Generate MongoDB migration steps between versions',
      {
        sourceVersion: z.string().describe('Source MongoDB version'),
        targetVersion: z.string().describe('Target MongoDB version'),
        features: z.string().optional().describe('Optional: specific features you use')
      },
      ({ sourceVersion, targetVersion, features }) => {
        log(`Prompt: Initializing [migration-guide] from ${sourceVersion} to ${targetVersion}.`)
        return {
          description: 'MongoDB Version Migration Guide',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need to migrate my MongoDB deployment from version ${sourceVersion} to ${targetVersion}.

  ${features ? `Key features I'm using: ${features}\n\n` : ''}
  Please provide:
  1. Step-by-step migration plan
  2. Pre-migration checks and preparations
  3. Breaking changes and deprecated features to be aware of
  4. New features or improvements I can leverage
  5. Common pitfalls and how to avoid them
  6. Performance considerations
  7. Rollback strategy in case of issues`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'sql-to-mongodb')) {
    server.prompt(
      'sql-to-mongodb',
      'Convert SQL queries to MongoDB aggregation pipelines',
      {
        sqlQuery: z.string().min(1).describe('SQL query to convert'),
        targetCollection: z.string().optional().describe('Target MongoDB collection name')
      },
      ({ sqlQuery, targetCollection }) => {
        log(`Prompt: Initializing [sql-to-mongodb] for query: "${sqlQuery}".`)
        return {
          description: 'SQL to MongoDB Query Translator',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please convert this SQL query to MongoDB syntax:\n\n\`\`\`sql\n${sqlQuery}\n\`\`\`\n\n${targetCollection ? `Target collection: ${targetCollection}` : ''}\n\nI need:
    1. The equivalent MongoDB query/aggregation pipeline with proper MongoDB operators
    2. Explanation of how each part of the SQL query maps to MongoDB
    3. How to execute this using MongoDB Lens tools
    4. Any important considerations or MongoDB-specific optimizations

    Please provide both the find() query format (if applicable) and the aggregation pipeline format.`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'database-health-check')) {
    server.prompt(
      'database-health-check',
      'Comprehensive database health assessment',
      {
        includePerformance: z.string().default('true').describe('Include performance metrics'),
        includeSchema: z.string().default('true').describe('Include schema analysis'),
        includeSecurity: z.string().default('true').describe('Include security assessment')
      },
      async ({ includePerformance, includeSchema, includeSecurity }) => {
        const includePerformanceBool = includePerformance.toLowerCase() === 'true'
        const includeSchemaBool = includeSchema.toLowerCase() === 'true'
        const includeSecurityBool = includeSecurity.toLowerCase() === 'true'

        log('Prompt: Initializing [database-health-check].')

        const dbStats = await getDatabaseStats()
        const collections = await listCollections()

        let serverStatus = null
        let indexes = {}
        let schemaAnalysis = {}

        if (includePerformanceBool) {
          serverStatus = await getServerStatus()
          const collectionsToAnalyze = collections.slice(0, 5)
          for (const coll of collectionsToAnalyze) {
            indexes[coll.name] = await getCollectionIndexes(coll.name)
          }
        }

        if (includeSchemaBool) {
          const collectionsToAnalyze = collections.slice(0, 3)
          for (const coll of collectionsToAnalyze) {
            schemaAnalysis[coll.name] = await inferSchema(coll.name, 10)
          }
        }

        let securityInfo = null
        if (includeSecurityBool) {
          const users = await getDatabaseUsers()
          securityInfo = {
            users,
            auth: serverStatus ? serverStatus.security : null
          }
        }

        return {
          description: `MongoDB Health Check: ${currentDbName}`,
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `Please perform a comprehensive health check on my MongoDB database "${currentDbName}" and provide recommendations for improvements.

      Database Statistics:
      ${JSON.stringify(dbStats, null, 2)}

      Collections (${collections.length}):
      ${collections.map(c => `- ${c.name}`).join('\n')}

      ${includePerformanceBool ? `\nPerformance Metrics:
      ${JSON.stringify(serverStatus ? {
        connections: serverStatus.connections,
        opcounters: serverStatus.opcounters,
        mem: serverStatus.mem
      } : {}, null, 2)}

      Indexes:
      ${Object.entries(indexes).map(([coll, idxs]) =>
        `- ${coll}: ${idxs.length} indexes`
      ).join('\n')}` : ''}

      ${includeSchemaBool ? `\nSchema Samples:
      ${Object.keys(schemaAnalysis).join(', ')}` : ''}

      ${includeSecurityBool ? `\nSecurity Information:
      - Users: ${securityInfo.users.users ? securityInfo.users.users.length : 'N/A'}
      - Authentication: ${securityInfo.auth && securityInfo.auth.authentication ?
      JSON.stringify(securityInfo.auth.authentication.mechanisms || securityInfo.auth.authentication) : 'N/A'}` : ''}

      Please provide:
      1. Overall health assessment
      2. Urgent issues that need addressing
      3. Performance optimization recommendations
      4. Schema design suggestions and improvements
      5. Security best practices and concerns
      6. Monitoring and maintenance recommendations
      7. Specific MongoDB Lens tools to use for implementing your recommendations`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'multi-tenant-design')) {
    server.prompt(
      'multi-tenant-design',
      'Design MongoDB multi-tenant database architecture',
      {
        tenantIsolation: z.enum(['database', 'collection', 'field']).describe('Level of tenant isolation required'),
        estimatedTenants: z.string().describe('Estimated number of tenants'),
        sharedFeatures: z.string().describe('Features/data that will be shared across tenants'),
        tenantSpecificFeatures: z.string().describe('Features/data unique to each tenant'),
        scalingPriorities: z.string().optional().describe('Primary scaling concerns (e.g., read-heavy, write-heavy)')
      },
      ({ tenantIsolation, estimatedTenants, sharedFeatures, tenantSpecificFeatures, scalingPriorities }) => {
        const estimatedTenantsNum = parseInt(estimatedTenants, 10) || 1
        log(`Prompt: Initializing [multi-tenant-design] with ${tenantIsolation} isolation level for ${estimatedTenantsNum} tenants.`)
        return {
          description: 'MongoDB Multi-Tenant Architecture Design',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need to design a multi-tenant MongoDB architecture with the following requirements:

    - Tenant isolation level: ${tenantIsolation}
    - Estimated number of tenants: ${estimatedTenants}
    - Shared features/data: ${sharedFeatures}
    - Tenant-specific features/data: ${tenantSpecificFeatures}
    ${scalingPriorities ? `- Scaling priorities: ${scalingPriorities}` : ''}

    Please provide:
    1. Recommended multi-tenant architecture for MongoDB
    2. Data model with collection structures and relationships
    3. Schema examples (in JSON) for each collection
    4. Indexing strategy for optimal tenant isolation and performance
    5. Security considerations and access control patterns
    6. Scaling approach as tenant count and data volume grow
    7. Query patterns to efficiently retrieve tenant-specific data
    8. Specific MongoDB features to leverage for multi-tenancy
    9. Potential challenges and mitigation strategies

    For context, I'm using MongoDB version ${mongoClient.topology?.lastIsMaster?.version || 'recent'} and want to ensure my architecture follows best practices.`
              }
            }
          ]
        }
      }
    )
  }

  if (!isDisabled('prompts', 'schema-versioning')) {
    server.prompt(
      'schema-versioning',
      'Manage schema evolution in MongoDB applications',
      {
        collection: z.string().min(1).describe('Collection name to version'),
        currentSchema: z.string().describe('Current schema structure (brief description)'),
        plannedChanges: z.string().describe('Planned schema changes'),
        migrationConstraints: z.string().optional().describe('Migration constraints (e.g., zero downtime)')
      },
      async ({ collection, currentSchema, plannedChanges, migrationConstraints }) => {
        log(`Prompt: Initializing [schema-versioning] for collection '${collection}'…`)

        const schema = await inferSchema(collection)

        return {
          description: 'MongoDB Schema Versioning Strategy',
          messages: [
            {
              role: 'user',
              content: {
                type: 'text',
                text: `I need to implement schema versioning/evolution for the '${collection}' collection in MongoDB. Please help me design a strategy.

    Current Schema Information:
    ${formatSchema(schema)}

    Current Schema Description:
    ${currentSchema}

    Planned Schema Changes:
    ${plannedChanges}

    ${migrationConstraints ? `Migration Constraints: ${migrationConstraints}` : ''}

    Please provide:
    1. Recommended approach to schema versioning in MongoDB
    2. Step-by-step migration plan for these specific changes
    3. Code examples showing how to handle both old and new schema versions
    4. Schema validation rules to enforce the new schema
    5. Performance considerations during migration
    6. Rollback strategy if needed
    7. Testing approach to validate the migration
    8. MongoDB Lens tools and commands to use for the migration process

    I want to ensure backward compatibility during this transition.`
              }
            }
          ]
        }
      }
    )
  }

  const totalRegisteredPrompts = Object.keys(server._registeredPrompts).length
  log(`Total MCP prompts: ${totalRegisteredPrompts}`)
}

const registerTools = (server) => {
  if (isDisabled('tools', true)) {
    log('All MCP tools disabled via configuration', true)
    return
  }

  if (!isDisabled('tools', 'connect-mongodb')) {
    server.tool(
      'connect-mongodb',
      'Connect to a different MongoDB URI or alias',
      {
        uri: z.string().min(1).describe('MongoDB connection URI or alias to connect to'),
        validateConnection: createBooleanSchema('Whether to validate the connection', 'true')
      },
      async ({ uri, validateConnection }) => {
        return withErrorHandling(async () => {
          try {
            if (!uri.includes('://') && !uri.includes('@') && !mongoUriMap.has(uri.toLowerCase())) {
              if (await isDatabaseName(uri)) {
                return {
                  content: [{
                    type: 'text',
                    text: `It seems you're trying to switch to database "${uri}" rather than connect to a new MongoDB instance. Please use the "use-database" tool instead.`
                  }]
                }
              }
            }

            const resolvedUri = resolveMongoUri(uri)
            await changeConnection(resolvedUri, validateConnection === 'true')
            return {
              content: [{
                type: 'text',
                text: `Successfully connected to MongoDB${mongoUriAlias ? ` (${mongoUriAlias})` : ''} at URI: ${obfuscateMongoUri(resolvedUri)}`
              }]
            }
          } catch (error) {
            if (mongoUriCurrent && mongoUriCurrent !== uri) {
              try {
                await changeConnection(mongoUriCurrent, true)
              } catch (reconnectError) {
                log(`Failed to reconnect to current URI: ${reconnectError.message}`, true)
              }
            }
            throw error
          }
        }, 'Error connecting to new MongoDB URI')
      }
    )
  }

  if (!isDisabled('tools', 'connect-original')) {
    server.tool(
      'connect-original',
      'Connect back to the original MongoDB URI used at startup',
      {
        validateConnection: createBooleanSchema('Whether to validate the connection', 'true')
      },
      async ({ validateConnection }) => {
        return withErrorHandling(async () => {
          if (!mongoUriOriginal) throw new Error('Original MongoDB URI not available')
          await changeConnection(mongoUriOriginal, validateConnection === 'true')
          return {
            content: [{
              type: 'text',
              text: `Successfully connected back to original MongoDB URI: ${obfuscateMongoUri(mongoUriOriginal)}`
            }]
          }
        }, 'Error connecting to original MongoDB URI')
      }
    )
  }

  if (!isDisabled('tools', 'add-connection-alias')) {
    server.tool(
      'add-connection-alias',
      'Add a new MongoDB connection alias',
      {
        alias: z.string().min(1).describe('Alias name for the connection'),
        uri: z.string().min(1).describe('MongoDB connection URI')
      },
      async ({ alias, uri }) => {
        return withErrorHandling(async () => {
          log(`Tool: Adding connection alias '${alias}'...`)

          if (!uri.includes('://') && !uri.includes('@')) {
            throw new Error(`Invalid MongoDB URI: ${uri}. URI must include protocol (mongodb://) or authentication (@)`)
          }

          const normalizedAlias = alias.toLowerCase()

          if (mongoUriMap.has(normalizedAlias)) {
            return {
              content: [{
                type: 'text',
                text: `Connection alias '${alias}' already exists. Use 'connect-mongodb' with the URI directly or choose a different alias.`
              }]
            }
          }

          mongoUriMap.set(normalizedAlias, uri)
          log(`Tool: Added connection alias '${alias}' for URI: ${obfuscateMongoUri(uri)}`)

          return {
            content: [{
              type: 'text',
              text: `Successfully added connection alias '${alias}' for MongoDB URI: ${obfuscateMongoUri(uri)}\n\nYou can now connect using: "Connect to ${alias}"`
            }]
          }
        }, `Error adding connection alias '${alias}'`)
      }
    )
  }

  if (!isDisabled('tools', 'list-connections')) {
    server.tool(
      'list-connections',
      'List all configured MongoDB connection aliases',
      async () => {
        return withErrorHandling(async () => {
          log('Tool: Listing configured MongoDB connections')

          if (mongoUriMap.size === 0) {
            return {
              content: [{
                type: 'text',
                text: 'No connection aliases configured.'
              }]
            }
          }

          let result = 'Configured MongoDB connections:\n'
          mongoUriMap.forEach((uri, alias) => {
            const obfuscatedUri = obfuscateMongoUri(uri)
            result += `- ${alias}: ${obfuscatedUri}${alias === mongoUriAlias ? ' (current)' : ''}\n`
          })

          return {
            content: [{
              type: 'text',
              text: result
            }]
          }
        }, 'Error listing MongoDB connections')
      }
    )
  }

  if (!isDisabled('tools', 'list-databases')) {
    server.tool(
      'list-databases',
      'List all accessible MongoDB databases',
      async () => {
        return withErrorHandling(async () => {
          log('Tool: Listing databases…')
          const dbs = await listDatabases()
          log(`Tool: Found ${dbs.length} databases.`)
          return {
            content: [{
              type: 'text',
              text: formatDatabasesList(dbs)
            }]
          }
        }, 'Error listing databases')
      }
    )
  }

  if (!isDisabled('tools', 'current-database')) {
    server.tool(
      'current-database',
      'Get the name of the current database',
      async () => {
        return withErrorHandling(async () => {
          log('Tool: Getting current database name…')
          return {
            content: [{
              type: 'text',
              text: `Current database: ${currentDbName}`
            }]
          }
        }, 'Error getting current database')
      }
    )
  }

  if (!isDisabled('tools', 'create-database')) {
    server.tool(
      'create-database',
      'Create a new MongoDB database with option to switch',
      {
        name: z.string().min(1).describe('Database name to create'),
        switch: createBooleanSchema('Whether to switch to the new database after creation', 'false'),
        validateName: createBooleanSchema('Whether to validate database name', 'true')
      },
      async ({ name, switch: shouldSwitch, validateName }) => {
        return withErrorHandling(async () => {
          log(`Tool: Creating database '${name}'${shouldSwitch === 'true' ? ' and switching to it' : ''}…`)
          const db = await createDatabase(name, validateName)

          if (shouldSwitch === 'true') {
            currentDbName = name
            currentDb = db
            log(`Tool: Switched to database '${name}'.`)
            return {
              content: [{
                type: 'text',
                text: `Database '${name}' created successfully and connected.`
              }]
            }
          } else {
            log(`Tool: Database '${name}' created successfully. Current database is still '${currentDbName}'.`)
            return {
              content: [{
                type: 'text',
                text: `Database '${name}' created successfully. Current database is still '${currentDbName}'.`
              }]
            }
          }
        }, `Error creating database '${name}'${shouldSwitch === 'true' ? ' and switching to it' : ''}`)
      }
    )
  }

  if (!isDisabled('tools', 'use-database')) {
    server.tool(
      'use-database',
      'Switch to a specific database',
      {
        database: z.string().min(1).describe('Database name to use')
      },
      async ({ database }) => {
        try {
          log(`Tool: Switching to database '${database}'…`)
          await switchDatabase(database)
          log(`Tool: Successfully switched to database '${database}'.`)
          return {
            content: [{
              type: 'text',
              text: `Switched to database: ${database}`
            }]
          }
        } catch (error) {
          log(`Error switching database: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error switching database: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'drop-database')) {
    server.tool(
      'drop-database',
      'Drop a database (requires confirmation)',
      {
        name: z.string().min(1).describe('Database name to drop'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ name, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing drop database request for '${name}'…`)

          if (config.disableDestructiveOperationTokens) {
            const result = await dropDatabase(name)
            return {
              content: [{
                type: 'text',
                text: result.message
              }]
            }
          }

          if (token) {
            if (!validateDropDatabaseToken(name, token)) {
              throw new Error(`Invalid or expired confirmation token for dropping '${name}'. Please try again without a token to generate a new confirmation code.`)
            }
            const result = await dropDatabase(name)
            return {
              content: [{
                type: 'text',
                text: result.message
              }]
            }
          }

          const dbs = await listDatabases()
          const dbExists = dbs.some(db => db.name === name)
          if (!dbExists) {
            throw new Error(`Database '${name}' does not exist`)
          }
          const newToken = storeDropDatabaseToken(name)
          return {
            content: [{
              type: 'text',
              text: `⚠️ DESTRUCTIVE OPERATION WARNING ⚠️\n\nYou've requested to drop the database '${name}'.\n\nThis operation is irreversible and will permanently delete all collections and data in this database.\n\nTo confirm, you must type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing database drop for '${name}'`)
      }
    )
  }

  if (!isDisabled('tools', 'create-user')) {
    server.tool(
      'create-user',
      'Create a new database user',
      {
        username: z.string().min(1).describe('Username'),
        password: z.string().min(1).describe('Password'),
        roles: z.string().describe('Roles as JSON array, e.g. [{"role": "readWrite", "db": "mydb"}]')
      },
      async ({ username, password, roles }) => {
        try {
          log(`Tool: Creating user '${username}'…`)
          const parsedRoles = JSON.parse(roles)
          await createUser(username, password, parsedRoles)
          log(`Tool: User created successfully.`)
          return {
            content: [{
              type: 'text',
              text: `User '${username}' created with roles: ${JSON.stringify(parsedRoles)}`
            }]
          }
        } catch (error) {
          log(`Error creating user: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error creating user: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'drop-user')) {
    server.tool(
      'drop-user',
      'Drop an existing database user',
      {
        username: z.string().min(1).describe('Username to drop'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ username, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing drop user request for '${username}'…`)

          if (config.disableDestructiveOperationTokens) {
            await dropUser(username)
            return {
              content: [{
                type: 'text',
                text: `User '${username}' dropped successfully.`
              }]
            }
          }

          if (token) {
            if (!validateDropUserToken(username, token)) {
              throw new Error(`Invalid or expired confirmation token. Please try again without a token to generate a new confirmation code.`)
            }
            await dropUser(username)
            return {
              content: [{
                type: 'text',
                text: `User '${username}' dropped successfully.`
              }]
            }
          }

          const newToken = storeDropUserToken(username)
          return {
            content: [{
              type: 'text',
              text: `⚠️ SECURITY OPERATION WARNING ⚠️\n\nYou've requested to drop the user '${username}'.\n\nThis operation will remove all access permissions for this user and is irreversible.\n\nTo confirm, type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing user drop for '${username}'`)
      }
    )
  }

  if (!isDisabled('tools', 'list-collections')) {
    server.tool(
      'list-collections',
      'List collections in the current database',
      async () => {
        try {
          log(`Tool: Listing collections in database '${currentDbName}'…`)
          const collections = await listCollections()
          log(`Tool: Found ${collections.length} collections in database '${currentDbName}'.`)
          return {
            content: [{
              type: 'text',
              text: formatCollectionsList(collections)
            }]
          }
        } catch (error) {
          log(`Error listing collections: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error listing collections: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'create-collection')) {
    server.tool(
      'create-collection',
      'Create a new collection with options',
      {
        name: z.string().min(1).describe('Collection name'),
        options: z.string().default('{}').describe('Collection options as JSON string (capped, size, etc.)')
      },
      async ({ name, options }) => {
        try {
          log(`Tool: Creating collection '${name}'…`)
          log(`Tool: Using options: ${options}`)

          const parsedOptions = options ? JSON.parse(options) : {}
          const result = await createCollection(name, parsedOptions)
          log(`Tool: Collection created successfully.`)
          return {
            content: [{
              type: 'text',
              text: `Collection '${name}' created successfully.`
            }]
          }
        } catch (error) {
          log(`Error creating collection: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error creating collection: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'drop-collection')) {
    server.tool(
      'drop-collection',
      'Drop a collection (requires confirmation)',
      {
        name: z.string().min(1).describe('Collection name to drop'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ name, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing drop collection request for '${name}'…`)

          if (config.disableDestructiveOperationTokens) {
            await dropCollection(name)
            return {
              content: [{
                type: 'text',
                text: `Collection '${name}' has been permanently deleted.`
              }]
            }
          }

          if (token) {
            if (!validateDropCollectionToken(name, token)) {
              throw new Error(`Invalid or expired confirmation token for dropping '${name}'. Please try again without a token to generate a new confirmation code.`)
            }
            await dropCollection(name)
            return {
              content: [{
                type: 'text',
                text: `Collection '${name}' has been permanently deleted.`
              }]
            }
          }

          await throwIfCollectionNotExists(name)
          const newToken = storeDropCollectionToken(name)
          return {
            content: [{
              type: 'text',
              text: `⚠️ DESTRUCTIVE OPERATION WARNING ⚠️\n\nYou've requested to drop the collection '${name}'.\n\nThis operation is irreversible and will permanently delete all data in this collection.\n\nTo confirm, you must type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing collection drop for '${name}'`)
      }
    )
  }

  if (!isDisabled('tools', 'rename-collection')) {
    server.tool(
      'rename-collection',
      'Rename an existing collection',
      {
        oldName: z.string().min(1).describe('Current collection name'),
        newName: z.string().min(1).describe('New collection name'),
        dropTarget: createBooleanSchema('Whether to drop target collection if it exists', 'false'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ oldName, newName, dropTarget, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing rename collection from '${oldName}' to '${newName}'…`)
          await throwIfCollectionNotExists(oldName)

          const collections = await listCollections()
          const targetExists = collections.some(c => c.name === newName)

          if (!targetExists || dropTarget !== 'true' || config.disableDestructiveOperationTokens) {
            const result = await renameCollection(oldName, newName, dropTarget === 'true')
            return {
              content: [{
                type: 'text',
                text: `Collection '${oldName}' renamed to '${newName}' successfully.`
              }]
            }
          }

          if (token) {
            if (!validateRenameCollectionToken(oldName, newName, dropTarget, token)) {
              throw new Error(`Invalid or expired confirmation token. Please try again without a token to generate a new confirmation code.`)
            }
            const result = await renameCollection(oldName, newName, true)
            return {
              content: [{
                type: 'text',
                text: `Collection '${oldName}' renamed to '${newName}' successfully.`
              }]
            }
          }

          const newToken = storeRenameCollectionToken(oldName, newName, dropTarget)
          return {
            content: [{
              type: 'text',
              text: `⚠️ DESTRUCTIVE OPERATION WARNING ⚠️\n\nYou've requested to rename collection '${oldName}' to '${newName}' and drop the existing target collection.\n\nDropping a collection is irreversible. To confirm, type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing rename for collection '${oldName}'`)
      }
    )
  }

  if (!isDisabled('tools', 'validate-collection')) {
    server.tool(
      'validate-collection',
      'Run validation on a collection to check for inconsistencies',
      {
        collection: z.string().min(1).describe('Collection name'),
        full: createBooleanSchema('Perform full validation (slower but more thorough)', 'false')
      },
      async ({ collection, full }) => {
        try {
          log(`Tool: Validating collection '${collection}'…`)
          log(`Tool: Full validation: ${full}`)

          const results = await validateCollection(collection, full)
          log(`Tool: Validation complete.`)
          return {
            content: [{
              type: 'text',
              text: formatValidationResults(results)
            }]
          }
        } catch (error) {
          log(`Error validating collection: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error validating collection: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'distinct-values')) {
    server.tool(
      'distinct-values',
      'Get unique values for a field',
      {
        collection: z.string().min(1).describe('Collection name'),
        field: z.string().min(1).describe('Field name to get distinct values for'),
        filter: z.string().default('{}').describe('Optional filter as JSON string')
      },
      async ({ collection, field, filter }) => {
        try {
          log(`Tool: Getting distinct values for field '${field}' in collection '${collection}'…`)
          log(`Tool: Using filter: ${filter}`)

          const parsedFilter = filter ? JSON.parse(filter) : {}
          const values = await getDistinctValues(collection, field, parsedFilter)
          log(`Tool: Found ${values.length} distinct values.`)
          return {
            content: [{
              type: 'text',
              text: formatDistinctValues(field, values)
            }]
          }
        } catch (error) {
          log(`Error getting distinct values: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error getting distinct values: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'find-documents')) {
    server.tool(
      'find-documents',
      'Run queries with filters and projections',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().default('{}').describe('MongoDB query filter (JSON string)'),
        projection: z.string().optional().describe('Fields to include/exclude (JSON string)'),
        limit: z.number().int().min(1).default(10).describe('Maximum number of documents to return'),
        skip: z.number().int().min(0).default(0).describe('Number of documents to skip'),
        sort: z.string().optional().describe('Sort specification (JSON string)'),
        streaming: createBooleanSchema('Enable streaming for large result sets', 'false')
      },
      async ({ collection, filter, projection, limit, skip, sort, streaming }) => {
        return withErrorHandling(async () => {
          log(`Tool: Finding documents in collection '${collection}'...`)
          log(`Tool: Using filter: ${filter}`)
          if (projection) log(`Tool: Using projection: ${projection}`)
          if (sort) log(`Tool: Using sort: ${sort}`)
          log(`Tool: Using limit: ${limit}, skip: ${skip}, streaming: ${streaming}`)

          const parsedFilter = filter ? JSON.parse(filter) : {}
          const parsedProjection = projection ? JSON.parse(projection) : null
          const parsedSort = sort ? JSON.parse(sort) : null

          const documents = await findDocuments(collection, parsedFilter, parsedProjection, limit, skip, parsedSort)
          log(`Tool: Found ${documents.length} documents in collection '${collection}'.`)
          return {
            content: [{
              type: 'text',
              text: formatDocuments(documents, limit)
            }]
          }
        }, `Error finding documents in collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'count-documents')) {
    server.tool(
      'count-documents',
      'Count documents with optional filter',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().default('{}').describe('MongoDB query filter (JSON string)')
      },
      async ({ collection, filter }) => {
        try {
          log(`Tool: Counting documents in collection '${collection}'…`)
          log(`Tool: Using filter: ${filter}`)

          const parsedFilter = filter ? JSON.parse(filter) : {}
          const count = await countDocuments(collection, parsedFilter)
          log(`Tool: Count result: ${count} documents.`)
          return {
            content: [{
              type: 'text',
              text: `Count: ${count} document(s)`
            }]
          }
        } catch (error) {
          log(`Error counting documents: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error counting documents: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'insert-document')) {
    server.tool(
      'insert-document',
      'Insert one or multiple documents into a collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        document: z.string().describe('Document as JSON string or array of documents'),
        options: z.string().optional().describe('Options as JSON string (including "ordered" for multiple documents)')
      },
      async ({ collection, document, options }) => {
        return withErrorHandling(async () => {
          log(`Tool: Inserting document(s) into collection '${collection}'…`)

          if (!document) throw new Error('Document is required for insert operation')
          const parsedDocument = JSON.parse(document)
          const parsedOptions = options ? JSON.parse(options) : {}

          const result = await insertDocument(collection, parsedDocument, parsedOptions)

          if (Array.isArray(parsedDocument)) {
            log(`Tool: Successfully inserted ${result.insertedCount} documents.`)
            return {
              content: [{
                type: 'text',
                text: `Successfully inserted ${result.insertedCount} documents.\n\nInserted IDs: ${
                  Object.values(result.insertedIds || {})
                    .map(id => id.toString())
                    .join(', ')
                }`
              }]
            }
          } else {
            log(`Tool: Document inserted successfully.`)
            return {
              content: [{
                type: 'text',
                text: formatInsertResult(result)
              }]
            }
          }
        }, `Error inserting document(s) into collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'update-document')) {
    server.tool(
      'update-document',
      'Update specific documents in a collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().describe('Filter as JSON string'),
        update: z.string().describe('Update operations as JSON string'),
        options: z.string().optional().describe('Options as JSON string')
      },
      async ({ collection, filter, update, options }) => {
        try {
          log(`Tool: Updating documents in collection '${collection}'…`)

          if (!filter) throw new Error('Filter is required for update operation')
          if (!update) throw new Error('Update is required for update operation')

          const parsedFilter = JSON.parse(filter)
          const parsedUpdate = JSON.parse(update)
          const parsedOptions = options ? JSON.parse(options) : {}

          const result = await updateDocument(collection, parsedFilter, parsedUpdate, parsedOptions)
          log(`Tool: Document(s) updated successfully.`)

          return {
            content: [{
              type: 'text',
              text: formatUpdateResult(result)
            }]
          }
        } catch (error) {
          console.error(`Error updating document:`, error)
          return {
            content: [{
              type: 'text',
              text: `Error updating document: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'delete-document')) {
    server.tool(
      'delete-document',
      'Delete document(s) (requires confirmation)',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().min(1).describe('Filter as JSON string'),
        many: createBooleanSchema('Delete multiple documents if true', 'false'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ collection, filter, many, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing delete document request for collection '${collection}'…`)
          const parsedFilter = JSON.parse(filter)

          if (config.disableDestructiveOperationTokens) {
            const options = { many: many === 'true' }
            const result = await deleteDocument(collection, parsedFilter, options)
            return {
              content: [{
                type: 'text',
                text: `Successfully deleted ${result.deletedCount} document(s) from collection '${collection}'.`
              }]
            }
          }

          if (token) {
            if (!validateDeleteDocumentToken(collection, parsedFilter, token)) {
              throw new Error(`Invalid or expired confirmation token. Please try again without a token to generate a new confirmation code.`)
            }
            const options = { many: many === 'true' }
            const result = await deleteDocument(collection, parsedFilter, options)
            return {
              content: [{
                type: 'text',
                text: `Successfully deleted ${result.deletedCount} document(s) from collection '${collection}'.`
              }]
            }
          }

          await throwIfCollectionNotExists(collection)
          const count = await countDocuments(collection, parsedFilter)
          const newToken = storeDeleteDocumentToken(collection, parsedFilter)
          return {
            content: [{
              type: 'text',
              text: `⚠️ DESTRUCTIVE OPERATION WARNING ⚠️\n\nYou've requested to delete ${many === 'true' ? 'all' : 'one'} document(s) from collection '${collection}' matching:\n${filter}\n\nThis matches approximately ${count} document(s).\n\nThis operation is irreversible. To confirm, type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing document delete for collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'aggregate-data')) {
    server.tool(
      'aggregate-data',
      'Run aggregation pipelines',
      {
        collection: z.string().min(1).describe('Collection name'),
        pipeline: z.string().describe('Aggregation pipeline as JSON string array'),
        streaming: createBooleanSchema('Enable streaming results for large datasets', 'false'),
        limit: z.number().int().min(1).default(1000).describe('Maximum number of results to return when streaming')
      },
      async ({ collection, pipeline, streaming, limit }) => {
        return withErrorHandling(async () => {
          log(`Tool: Running aggregation on collection '${collection}'...`)
          log(`Tool: Using pipeline: ${pipeline}`)
          log(`Tool: Streaming: ${streaming}, Limit: ${limit}`)

          const parsedPipeline = JSON.parse(pipeline)
          const processedPipeline = processAggregationPipeline(parsedPipeline)

          const results = await aggregateData(collection, processedPipeline)
          log(`Tool: Aggregation returned ${results.length} results.`)
          return {
            content: [{
              type: 'text',
              text: formatDocuments(results, 100)
            }]
          }
        }, `Error running aggregation on collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'create-index')) {
    server.tool(
      'create-index',
      'Create new index on collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        keys: z.string().describe('Index keys as JSON object'),
        options: z.string().optional().describe('Index options as JSON object')
      },
      async ({ collection, keys, options }) => {
        try {
          log(`Tool: Creating index on collection '${collection}'…`)
          log(`Tool: Index keys: ${keys}`)
          if (options) log(`Tool: Index options: ${options}`)

          const parsedKeys = JSON.parse(keys)
          const parsedOptions = options ? JSON.parse(options) : {}

          const result = await createIndex(collection, parsedKeys, parsedOptions)
          log(`Tool: Index created successfully: ${result}`)
          return {
            content: [{
              type: 'text',
              text: `Index created: ${result}`
            }]
          }
        } catch (error) {
          log(`Error creating index: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error creating index: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'drop-index')) {
    server.tool(
      'drop-index',
      'Drop an existing index from a collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        indexName: z.string().min(1).describe('Name of the index to drop'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ collection, indexName, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing drop index request for '${indexName}' on collection '${collection}'…`)

          if (config.disableDestructiveOperationTokens) {
            await dropIndex(collection, indexName)
            return {
              content: [{
                type: 'text',
                text: `Index '${indexName}' dropped from collection '${collection}' successfully.`
              }]
            }
          }

          if (token) {
            if (!validateDropIndexToken(collection, indexName, token)) {
              throw new Error(`Invalid or expired confirmation token. Please try again without a token to generate a new confirmation code.`)
            }
            await dropIndex(collection, indexName)
            return {
              content: [{
                type: 'text',
                text: `Index '${indexName}' dropped from collection '${collection}' successfully.`
              }]
            }
          }

          await throwIfCollectionNotExists(collection)
          const indexes = await getCollectionIndexes(collection)
          const indexExists = indexes.some(idx => idx.name === indexName)

          if (!indexExists) {
            throw new Error(`Index '${indexName}' does not exist on collection '${collection}'`)
          }

          const newToken = storeDropIndexToken(collection, indexName)
          return {
            content: [{
              type: 'text',
              text: `⚠️ PERFORMANCE IMPACT WARNING ⚠️\n\nYou've requested to drop the index '${indexName}' from collection '${collection}'.\n\nDropping this index may impact query performance. To confirm, type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing index drop for '${indexName}' on collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'get-stats')) {
    server.tool(
      'get-stats',
      'Get database or collection statistics',
      {
        target: z.enum(['database', 'collection']).describe('Target type'),
        name: z.string().optional().describe('Collection name (for collection stats)')
      },
      async ({ target, name }) => {
        try {
          let stats
          if (target === 'database') {
            log(`Tool: Getting statistics for database '${currentDbName}'…`)
            stats = await getDatabaseStats()
            log(`Tool: Retrieved database statistics.`)
          } else if (target === 'collection') {
            if (!name) throw new Error('Collection name is required for collection stats')
            log(`Tool: Getting statistics for collection '${name}'…`)
            stats = await getCollectionStats(name)
            log(`Tool: Retrieved collection statistics.`)
          }

          return {
            content: [{
              type: 'text',
              text: formatStats(stats)
            }]
          }
        } catch (error) {
          log(`Error getting stats: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error getting stats: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'analyze-schema')) {
    server.tool(
      'analyze-schema',
      'Automatically infer schema from collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        sampleSize: z.number().int().min(1).default(100).describe('Number of documents to sample')
      },
      async ({ collection, sampleSize }) => {
        try {
          log(`Tool: Analyzing schema for collection '${collection}' with sample size ${sampleSize}…`)
          const schema = await inferSchema(collection, sampleSize)
          log(`Tool: Schema analysis complete for '${collection}', found ${Object.keys(schema.fields).length} fields.`)
          return {
            content: [{
              type: 'text',
              text: formatSchema(schema)
            }]
          }
        } catch (error) {
          log(`Error inferring schema: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error inferring schema: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'generate-schema-validator')) {
    server.tool(
      'generate-schema-validator',
      'Generate a JSON Schema validator for a collection',
      {
        collection: z.string().min(1).describe('Collection name'),
        strictness: z.enum(['strict', 'moderate', 'relaxed']).default('moderate').describe('Validation strictness level')
      },
      async ({ collection, strictness }) => {
        return withErrorHandling(async () => {
          log(`Tool: Generating schema validator for '${collection}' with ${strictness} strictness`)

          const schema = await inferSchema(collection, 200)

          const validator = generateJsonSchemaValidator(schema, strictness)

          const result = `# MongoDB JSON Schema Validator for '${collection}'

  ## Schema Validator
  \`\`\`json
  ${JSON.stringify(validator, null, 2)}
  \`\`\`

  ## How to Apply This Validator

  ### MongoDB Shell Command
  \`\`\`javascript
  db.runCommand({
    collMod: "${collection}",
    validator: ${JSON.stringify(validator, null, 2)},
    validationLevel: "${strictness === 'relaxed' ? 'moderate' : strictness}",
    validationAction: "${strictness === 'strict' ? 'error' : 'warn'}"
  })
  \`\`\`

  ### Using modify-document Tool in MongoDB Lens
  \`\`\`
  modify-document {
    "collection": "system.command",
    "operation": "insert",
    "document": {
      "collMod": "${collection}",
      "validator": ${JSON.stringify(validator)},
      "validationLevel": "${strictness === 'relaxed' ? 'moderate' : strictness}",
      "validationAction": "${strictness === 'strict' ? 'error' : 'warn'}"
    }
  }
  \`\`\`

  This schema validator was generated based on ${schema.sampleSize} sample documents with ${Object.keys(schema.fields).length} fields.
  `

          return {
            content: [{
              type: 'text',
              text: result
            }]
          }
        }, `Error generating schema validator for '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'compare-schemas')) {
    server.tool(
      'compare-schemas',
      'Compare schemas between two collections',
      {
        sourceCollection: z.string().min(1).describe('Source collection name'),
        targetCollection: z.string().min(1).describe('Target collection name'),
        sampleSize: z.number().int().min(1).default(100).describe('Number of documents to sample')
      },
      async ({ sourceCollection, targetCollection, sampleSize }) => {
        return withErrorHandling(async () => {
          log(`Tool: Comparing schemas between '${sourceCollection}' and '${targetCollection}'…`)

          const sourceSchema = await inferSchema(sourceCollection, sampleSize)
          const targetSchema = await inferSchema(targetCollection, sampleSize)

          const comparison = compareSchemas(sourceSchema, targetSchema)

          return {
            content: [{
              type: 'text',
              text: formatSchemaComparison(comparison, sourceCollection, targetCollection)
            }]
          }
        }, `Error comparing schemas between '${sourceCollection}' and '${targetCollection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'explain-query')) {
    server.tool(
      'explain-query',
      'Analyze query performance',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().describe('MongoDB query filter (JSON string)'),
        verbosity: z.enum(['queryPlanner', 'executionStats', 'allPlansExecution']).default('executionStats').describe('Explain verbosity level')
      },
      async ({ collection, filter, verbosity }) => {
        try {
          log(`Tool: Explaining query on collection '${collection}'…`)
          log(`Tool: Filter: ${filter}`)
          log(`Tool: Verbosity level: ${verbosity}`)

          const parsedFilter = JSON.parse(filter)
          const explanation = await explainQuery(collection, parsedFilter, verbosity)
          log(`Tool: Query explanation generated.`)

          const fields = await getCollectionFields(collection)
          const fieldInfo = fields.length > 0 ?
            `\n\nAvailable fields for projection: ${fields.join(', ')}` : ''

          const suggestedProjection = getSuggestedProjection(parsedFilter, fields)
          const projectionInfo = suggestedProjection ?
            `\n\nSuggested projection: ${suggestedProjection}` : ''

          return {
            content: [{
              type: 'text',
              text: formatExplanation(explanation) + fieldInfo + projectionInfo
            }]
          }
        } catch (error) {
          log(`Error explaining query: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error explaining query: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'analyze-query-patterns')) {
    server.tool(
      'analyze-query-patterns',
      'Analyze query patterns and suggest optimizations',
      {
        collection: z.string().min(1).describe('Collection name to analyze'),
        duration: z.number().int().min(1).max(60).default(config.tools.queryAnalysis.defaultDurationSeconds).describe('Duration to analyze in seconds')
      },
      async ({ collection, duration }) => {
        return withErrorHandling(async () => {
          log(`Tool: Analyzing query patterns for collection '${collection}'…`)

          await throwIfCollectionNotExists(collection)
          const indexes = await getCollectionIndexes(collection)
          const schema = await inferSchema(collection)

          await setProfilerSlowMs()

          let queryStats = []
          try {
            const adminDb = mongoClient.db('admin')
            const profilerStatus = await currentDb.command({ profile: -1 })

            let prevProfileLevel = profilerStatus.was
            let prevSlowMs = profilerStatus.slowms

            await currentDb.command({ profile: 2, slowms: 0 })

            log(`Tool: Monitoring queries for ${duration} seconds…`)

            await new Promise(resolve => setTimeout(resolve, duration * 1000))

            queryStats = await currentDb.collection('system.profile')
              .find({ ns: `${currentDbName}.${collection}`, op: 'query' })
              .sort({ ts: -1 })
              .limit(100)
              .toArray()

            await currentDb.command({ profile: prevProfileLevel, slowms: prevSlowMs })

          } catch (profileError) {
            log(`Tool: Unable to use profiler: ${profileError.message}`)
          }

          const analysis = analyzeQueryPatterns(collection, schema, indexes, queryStats)

          return {
            content: [{
              type: 'text',
              text: formatQueryAnalysis(analysis)
            }]
          }
        }, `Error analyzing query patterns for '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'bulk-operations')) {
    server.tool(
      'bulk-operations',
      'Perform bulk inserts, updates, or deletes',
      {
        collection: z.string().min(1).describe('Collection name'),
        operations: z.string().describe('Array of operations as JSON string'),
        ordered: createBooleanSchema('Whether operations should be performed in order', 'true'),
        token: z.string().optional().describe('Confirmation token from previous request')
      },
      async ({ collection, operations, ordered, token }) => {
        return withErrorHandling(async () => {
          log(`Tool: Processing bulk operations on collection '${collection}'…`)
          const parsedOperations = JSON.parse(operations)

          const deleteOps = parsedOperations.filter(op =>
            op.deleteOne || op.deleteMany
          )

          if (deleteOps.length === 0 || config.disableDestructiveOperationTokens) {
            const result = await bulkOperations(collection, parsedOperations, ordered === 'true')
            return {
              content: [{
                type: 'text',
                text: formatBulkResult(result)
              }]
            }
          }

          if (token) {
            if (!validateBulkOperationsToken(collection, parsedOperations, token)) {
              throw new Error(`Invalid or expired confirmation token. Please try again without a token to generate a new confirmation code.`)
            }
            const result = await bulkOperations(collection, parsedOperations, ordered === 'true')
            return {
              content: [{
                type: 'text',
                text: formatBulkResult(result)
              }]
            }
          }

          await throwIfCollectionNotExists(collection)
          const newToken = storeBulkOperationsToken(collection, parsedOperations)
          return {
            content: [{
              type: 'text',
              text: `⚠️ DESTRUCTIVE OPERATION WARNING ⚠️\n\nYou've requested to perform bulk operations on collection '${collection}' including ${deleteOps.length} delete operation(s).\n\nDelete operations are irreversible. To confirm, type the 4-digit confirmation code EXACTLY as shown below:\n\nConfirmation code: ${newToken}\n\nThis code will expire in 5 minutes for security purposes.\n\n${importantNoticeToAI}`
            }]
          }
        }, `Error processing bulk operations for collection '${collection}'`)
      }
    )
  }

  if (!isDisabled('tools', 'create-timeseries')) {
    server.tool(
      'create-timeseries',
      'Create a time series collection for temporal data',
      {
        name: z.string().min(1).describe('Collection name'),
        timeField: z.string().min(1).describe('Field that contains the time value'),
        metaField: z.string().optional().describe('Field that contains metadata for grouping'),
        granularity: z.enum(['seconds', 'minutes', 'hours']).default('seconds').describe('Time series granularity'),
        expireAfterSeconds: z.number().int().optional().describe('Optional TTL in seconds')
      },
      async ({ name, timeField, metaField, granularity, expireAfterSeconds }) => {
        try {
          log(`Tool: Creating time series collection '${name}'…`)

          const adminDb = mongoClient.db('admin')
          const serverInfo = await adminDb.command({ buildInfo: 1 })
          const versionParts = serverInfo.version.split('.').map(Number)
          if (versionParts[0] < 5) {
            return { content: [{ type: 'text', text: `Time series collections require MongoDB 5.0+` }] }
          }

          const options = {
            timeseries: {
              timeField,
              granularity
            }
          }

          if (metaField) options.timeseries.metaField = metaField
          if (expireAfterSeconds) options.expireAfterSeconds = expireAfterSeconds

          const result = await createCollection(name, options)
          return {
            content: [{
              type: 'text',
              text: `Time series collection '${name}' created successfully.`
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error creating time series collection: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'collation-query')) {
    server.tool(
      'collation-query',
      'Find documents with language-specific collation rules',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().default('{}').describe('Query filter as JSON string'),
        locale: z.string().min(2).describe('Locale code (e.g., "en", "fr", "de")'),
        strength: z.number().int().min(1).max(5).default(3).describe('Collation strength (1-5)'),
        caseLevel: createBooleanSchema('Consider case in first-level differences', 'false'),
        sort: z.string().optional().describe('Sort specification as JSON string')
      },
      async ({ collection, filter, locale, strength, caseLevel, sort }) => {
        try {
          log(`Tool: Running collation query on collection '${collection}' with locale '${locale}'`)

          const parsedFilter = JSON.parse(filter)
          const parsedSort = sort ? JSON.parse(sort) : null

          const collationOptions = {
            locale,
            strength,
            caseLevel
          }

          const coll = currentDb.collection(collection)
          let query = coll.find(parsedFilter).collation(collationOptions)

          if (parsedSort) query = query.sort(parsedSort)

          const results = await query.toArray()

          return {
            content: [{
              type: 'text',
              text: formatCollationResults(results, locale, strength, caseLevel)
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error running collation query: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'text-search')) {
    server.tool(
      'text-search',
      'Perform full-text search across text-indexed fields',
      {
        collection: z.string().min(1).describe('Collection name'),
        searchText: z.string().min(1).describe('Text to search for'),
        language: z.string().optional().describe('Optional language for text search'),
        caseSensitive: createBooleanSchema('Case sensitive search', 'false'),
        diacriticSensitive: createBooleanSchema('Diacritic sensitive search', 'false'),
        limit: z.number().int().min(1).default(10).describe('Maximum results to return')
      },
      async ({ collection, searchText, language, caseSensitive, diacriticSensitive, limit }) => {
        try {
          log(`Tool: Performing text search in collection '${collection}' for: "${searchText}"`)

          try {
            const coll = currentDb.collection(collection)
            const indexes = await coll.listIndexes().toArray()
            const hasTextIndex = indexes.some(idx => Object.values(idx.key).includes('text'))

            if (!hasTextIndex) {
              return {
                content: [{
                  type: 'text',
                  text: `No text index found on collection '${collection}'.\n\nText search requires a text index. Create one with:\n\ncreate-index {\n  "collection": "${collection}",\n  "keys": "{\\"fieldName\\": \\"text\\"}"\n}`
                }]
              }
            }
          } catch (indexError) {
            log(`Warning: Unable to check for text indexes: ${indexError.message}`, true)
          }

          const textQuery = { $search: searchText }
          if (language) textQuery.$language = language
          if (caseSensitive === 'true') textQuery.$caseSensitive = true
          if (diacriticSensitive === 'true') textQuery.$diacriticSensitive = true

          const query = { $text: textQuery }
          const projection = { score: { $meta: 'textScore' } }
          const sort = { score: { $meta: 'textScore' } }

          const results = await findDocuments(collection, query, projection, limit, 0, sort)

          return {
            content: [{
              type: 'text',
              text: formatTextSearchResults(results, searchText)
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error performing text search: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'geo-query')) {
    server.tool(
      'geo-query',
      'Run geospatial queries with various operators',
      {
        collection: z.string().min(1).describe('Collection name'),
        operator: z.enum(['near', 'geoWithin', 'geoIntersects']).describe('Geospatial operator type'),
        field: z.string().min(1).describe('Geospatial field name'),
        geometry: z.string().describe('GeoJSON geometry as JSON string'),
        maxDistance: z.number().optional().describe('Maximum distance in meters (for near queries)'),
        limit: z.number().int().min(1).default(10).describe('Maximum number of documents to return')
      },
      async ({ collection, operator, field, geometry, maxDistance, limit }) => {
        try {
          log(`Tool: Running geospatial query on collection '${collection}'…`)

          let indexMessage = ''
          try {
            const coll = currentDb.collection(collection)
            const indexes = await coll.listIndexes().toArray()

            const hasGeoIndex = indexes.some(idx => {
              if (!idx.key[field]) return false
              const indexType = idx.key[field]
              return indexType === '2dsphere' || indexType === '2d'
            })

            if (!hasGeoIndex) {
              log(`Warning: No geospatial index found for field '${field}' in collection '${collection}'`, true)
              indexMessage = "\n\nNote: This query would be more efficient with a geospatial index. " +
                `Consider creating a 2dsphere index with: create-index {"collection": "${collection}", "keys": "{\\"${field}\\": \\"2dsphere\\"}"}`
            }
          } catch (indexError) {
            log(`Warning: Unable to check for geospatial indexes: ${indexError.message}`, true)
          }

          const geoJson = JSON.parse(geometry)
          let query = {}

          if (operator === 'near') {
            query[field] = { $near: { $geometry: geoJson } }
            if (maxDistance) query[field].$near.$maxDistance = maxDistance
          } else if (operator === 'geoWithin') {
            query[field] = { $geoWithin: { $geometry: geoJson } }
          } else if (operator === 'geoIntersects') {
            query[field] = { $geoIntersects: { $geometry: geoJson } }
          }

          const results = await findDocuments(collection, query, null, limit, 0)
          const resultText = formatDocuments(results, limit) + indexMessage

          return {
            content: [{
              type: 'text',
              text: resultText
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error running geospatial query: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'transaction')) {
    server.tool(
      'transaction',
      'Execute multiple operations in a single transaction',
      {
        operations: z.string().describe('JSON array of operations with collection, operation type, and parameters')
      },
      async ({ operations }) => {
        try {
          log('Tool: Executing operations in a transaction…')

          try {
            const session = mongoClient.startSession()
            await session.endSession()
          } catch (error) {
            if (error.message.includes('not supported') ||
                error.message.includes('requires replica set') ||
                error.codeName === 'NotAReplicaSet') {
              return {
                content: [{
                  type: 'text',
                  text: `Transactions are not supported on your MongoDB deployment.\n\nTransactions require MongoDB to be running as a replica set or sharded cluster. You appear to be running a standalone server.\n\nAlternative: You can set up a single-node replica set for development purposes by following these steps:\n\n1. Stop your MongoDB server\n2. Start it with the --replSet option: \`mongod --replSet rs0\`\n3. Connect to it and initialize the replica set: \`rs.initiate()\`\n\nThen try the transaction tool again.`
                }]
              }
            }
            throw error
          }

          const parsedOps = JSON.parse(operations)
          const session = mongoClient.startSession()
          let results = []

          try {
            session.startTransaction({
              readConcern: { level: config.tools.transaction.readConcern },
              writeConcern: config.tools.transaction.writeConcern
            })

            for (let i = 0; i < parsedOps.length; i++) {
              const op = parsedOps[i]
              log(`Tool: Transaction step ${i+1}: ${op.operation} on ${op.collection}`)

              let result
              const collection = currentDb.collection(op.collection)

              if (op.operation === 'insert') {
                result = await collection.insertOne(op.document, { session })
              } else if (op.operation === 'update') {
                result = await collection.updateOne(op.filter, op.update, { session })
              } else if (op.operation === 'delete') {
                result = await collection.deleteOne(op.filter, { session })
              } else if (op.operation === 'find') {
                result = await collection.findOne(op.filter, { session })
              } else {
                throw new Error(`Unsupported operation: ${op.operation}`)
              }

              results.push({ step: i+1, operation: op.operation, result })
            }

            await session.commitTransaction()
            log('Tool: Transaction committed successfully')
          } catch (error) {
            await session.abortTransaction()
            log(`Tool: Transaction aborted due to error: ${error.message}`)
            throw error
          } finally {
            await session.endSession()
          }

          return {
            content: [{
              type: 'text',
              text: formatTransactionResults(results)
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error executing transaction: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'map-reduce')) {
    server.tool(
      'map-reduce',
      'Run Map-Reduce operations (note: Map-Reduce deprecated as of MongoDB 5.0)',
      {
        collection: z.string().min(1).describe('Collection name'),
        map: z.string().describe('Map function as string e.g. "function() { emit(this.field, 1); }"'),
        reduce: z.string().describe('Reduce function as string e.g. "function(key, values) { return Array.sum(values); }"'),
        options: z.string().optional().describe('Options as JSON string (query, limit, etc.)')
      },
      async ({ collection, map, reduce, options }) => {
        try {
          log(`Tool: Running Map-Reduce on collection '${collection}'…`)
          const mapFunction = eval(`(${map})`)
          const reduceFunction = eval(`(${reduce})`)
          const parsedOptions = options ? JSON.parse(options) : {}
          const results = await runMapReduce(collection, mapFunction, reduceFunction, parsedOptions)
          log(`Tool: Map-Reduce operation complete.`)
          return {
            content: [{
              type: 'text',
              text: formatMapReduceResults(results)
            }]
          }
        } catch (error) {
          log(`Error running Map-Reduce: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error running Map-Reduce: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'watch-changes')) {
    server.tool(
      'watch-changes',
      'Watch for changes in a collection using change streams',
      {
        collection: z.string().min(1).describe('Collection name'),
        operations: z.array(z.enum(['insert', 'update', 'delete', 'replace'])).default(['insert', 'update', 'delete']).describe('Operations to watch'),
        duration: z.number().int().min(1).max(60).default(config.tools.watchChanges.defaultDurationSeconds).describe('Duration to watch in seconds'),
        fullDocument: createBooleanSchema('Include full document in update events', 'false')
      },
      async ({ collection, operations, duration, fullDocument }) => {
        try {
          log(`Tool: Watching collection '${collection}' for changes…`)

          let maxDuration = config.tools.watchChanges.maxDurationSeconds
          let actualDuration = duration

          if (actualDuration > maxDuration) {
            log(`Requested duration ${actualDuration}s exceeds maximum ${maxDuration}s, using maximum`, true)
            actualDuration = maxDuration
          }

          try {
            const adminDb = mongoClient.db('admin')
            await adminDb.command({ replSetGetStatus: 1 })
          } catch (err) {
            if (err.codeName === 'NotYetInitialized' ||
                err.codeName === 'NoReplicationEnabled' ||
                err.message.includes('not running with --replSet') ||
                err.code === 76 || err.code === 40573) {
              return {
                content: [{
                  type: 'text',
                  text: `Change streams are not supported on your MongoDB deployment.\n\nChange streams require MongoDB to be running as a replica set or sharded cluster. You appear to be running a standalone server.\n\nAlternative: You can set up a single-node replica set for development purposes by following these steps:\n\n1. Stop your MongoDB server\n2. Start it with the --replSet option: \`mongod --replSet rs0\`\n3. Connect to it and initialize the replica set: \`rs.initiate()\`\n\nThen try the watch-changes tool again.`
                }]
              }
            }
          }

          const pipeline = [
            { $match: { 'operationType': { $in: operations } } }
          ]

          const options = {}
          if (fullDocument) options.fullDocument = 'updateLookup'

          const coll = currentDb.collection(collection)
          const changeStream = coll.watch(pipeline, options)

          const changes = []
          const timeout = setTimeout(() => {
            changeStream.close()
          }, actualDuration * 1000)

          changeStream.on('change', change => {
            changes.push(change)
          })

          return new Promise(resolve => {
            changeStream.on('close', () => {
              clearTimeout(timeout)
              resolve({
                content: [{
                  type: 'text',
                  text: formatChangeStreamResults(changes, actualDuration)
                }]
              })
            })
          })
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error watching for changes: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'gridfs-operation')) {
    server.tool(
      'gridfs-operation',
      'Manage large files with GridFS',
      {
        operation: z.enum(['list', 'info', 'delete']).describe('GridFS operation type'),
        bucket: z.string().default('fs').describe('GridFS bucket name'),
        filename: z.string().optional().describe('Filename for info/delete operations'),
        limit: z.number().int().min(1).default(20).describe('Maximum files to list')
      },
      async ({ operation, bucket, filename, limit }) => {
        try {
          log(`Tool: Performing GridFS ${operation} operation on bucket '${bucket}'`)

          const gridFsBucket = new mongodb.GridFSBucket(currentDb, { bucketName: bucket })
          let result

          if (operation === 'list') {
            const files = await currentDb.collection(`${bucket}.files`).find({}).limit(limit).toArray()
            result = formatGridFSList(files)
          } else if (operation === 'info') {
            if (!filename) throw new Error('Filename is required for info operation')
            const file = await currentDb.collection(`${bucket}.files`).findOne({ filename })
            if (!file) throw new Error(`File '${filename}' not found`)
            result = formatGridFSInfo(file)
          } else if (operation === 'delete') {
            if (!filename) throw new Error('Filename is required for delete operation')
            await gridFsBucket.delete(await getFileId(bucket, filename))
            result = `File '${filename}' deleted successfully from bucket '${bucket}'`
          }

          return {
            content: [{
              type: 'text',
              text: result
            }]
          }
        } catch (error) {
          return {
            content: [{
              type: 'text',
              text: `Error performing GridFS operation: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  if (!isDisabled('tools', 'shard-status')) {
    server.tool(
      'shard-status',
      'Get sharding status for database or collections',
      {
        target: z.enum(['database', 'collection']).default('database').describe('Target type'),
        collection: z.string().optional().describe('Collection name (if target is collection)')
      },
      async ({ target, collection }) => {
        return withErrorHandling(async () => {
          log(`Tool: Getting shard status for ${target}${collection ? ` '${collection}'` : ''}`)

          try {
            const adminDb = mongoClient.db('admin')
            await adminDb.command({ listShards: 1 })
          } catch (error) {
            if (error.code === 72 || error.message.includes('not running with sharding') ||
                error.codeName === 'InvalidOptions') {
              return {
                content: [{
                  type: 'text',
                  text: `Sharding is not enabled on your MongoDB deployment.\n\nThis command requires MongoDB to be running as a sharded cluster.\nYou appear to be running a standalone server or replica set without sharding enabled.\n\nTo use sharding features, you need to set up a sharded cluster with:\n- Config servers\n- Mongos router(s)\n- Shard replica sets`
                }]
              }
            }
            throw error
          }

          const adminDb = mongoClient.db('admin')
          let result

          if (target === 'database') {
            const listShards = await adminDb.command({ listShards: 1 })
            const dbStats = await adminDb.command({ dbStats: 1, scale: 1 })
            const dbShardStatus = await getShardingDbStatus(currentDbName)

            result = formatShardDbStatus(listShards, dbStats, dbShardStatus, currentDbName)
          } else {
            if (!collection) throw new Error('Collection name is required when target is collection')

            const collStats = await currentDb.command({ collStats: collection })
            const collShardStatus = await getShardingCollectionStatus(currentDbName, collection)

            result = formatShardCollectionStatus(collStats, collShardStatus, collection)
          }

          return {
            content: [{
              type: 'text',
              text: result
            }]
          }
        }, `Error getting shard status for ${target}${collection ? ` '${collection}'` : ''}`)
      }
    )
  }

  if (!isDisabled('tools', 'export-data')) {
    server.tool(
      'export-data',
      'Export query results to formatted JSON or CSV',
      {
        collection: z.string().min(1).describe('Collection name'),
        filter: z.string().default('{}').describe('Filter as JSON string'),
        format: z.enum(['json', 'csv']).default('json').describe('Export format'),
        fields: z.string().optional().describe('Comma-separated list of fields to include (for CSV)'),
        limit: z.number().int().min(1).default(1000).describe('Maximum documents to export'),
        sort: z.string().optional().describe('Sort specification as JSON string (e.g. {"date": -1} for descending)')
      },
      async ({ collection, filter, format, fields, limit, sort }) => {
        try {
          log(`Tool: Exporting data from collection '${collection}' in ${format} format…`)
          log(`Tool: Using filter: ${filter}`)
          if (sort) log(`Tool: Using sort: ${sort}`)
          log(`Tool: Max documents: ${limit}`)

          const parsedFilter = filter ? JSON.parse(filter) : {}
          const parsedSort = sort ? JSON.parse(sort) : null
          let fieldsArray = fields ? fields.split(',').map(f => f.trim()) : null

          const documents = await findDocuments(collection, parsedFilter, null, limit, 0, parsedSort)
          log(`Tool: Found ${documents.length} documents to export.`)

          const exportData = await formatExport(documents, format, fieldsArray)
          log(`Tool: Data exported successfully in ${format} format.`)

          return {
            content: [{
              type: 'text',
              text: exportData
            }]
          }
        } catch (error) {
          log(`Error exporting data: ${error.message}`, true)
          return {
            content: [{
              type: 'text',
              text: `Error exporting data: ${error.message}`
            }],
            isError: true
          }
        }
      }
    )
  }

  const totalRegisteredTools = Object.keys(server._registeredTools).length
  log(`Total MCP tools: ${totalRegisteredTools}`)
}

const withErrorHandling = async (operation, errorMessage, defaultValue = null) => {
  try {
    return await operation()
  } catch (error) {
    const formattedError = `${errorMessage}: ${error.message}`
    log(formattedError, true)

    let errorCode = JSONRPC_ERROR_CODES.SERVER_ERROR_START
    let errorType = error.name || 'Error'

    if (error.name === 'MongoError' || error.name === 'MongoServerError') {
      switch(error.code) {
        case 13:
          errorCode = JSONRPC_ERROR_CODES.RESOURCE_ACCESS_DENIED; break
        case 59: case 61:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_CONNECTION_ERROR; break
        case 121:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_SCHEMA_ERROR; break
        case 11000:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_DUPLICATE_KEY; break
        case 112: case 16500:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_WRITE_ERROR; break
        case 50: case 57:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_TIMEOUT_ERROR; break
        default:
          errorCode = JSONRPC_ERROR_CODES.MONGODB_QUERY_ERROR
      }
    } else if (error.message.match(/not found|does not exist|cannot find/i)) {
      errorCode = JSONRPC_ERROR_CODES.RESOURCE_NOT_FOUND
    } else if (error.message.match(/already exists|duplicate/i)) {
      errorCode = JSONRPC_ERROR_CODES.RESOURCE_ALREADY_EXISTS
    } else if (error.message.match(/permission|access denied|unauthorized/i)) {
      errorCode = JSONRPC_ERROR_CODES.RESOURCE_ACCESS_DENIED
    } else if (error.message.match(/timeout|timed out/i)) {
      errorCode = JSONRPC_ERROR_CODES.MONGODB_TIMEOUT_ERROR
    }

    return {
      content: [{
        type: 'text',
        text: formattedError
      }],
      isError: true,
      error: {
        code: errorCode,
        message: error.message,
        data: {
          type: errorType,
          details: error.code ? `MongoDB error code: ${error.code}` : undefined
        }
      }
    }
  }
}

const isDatabaseName = async (name) => {
  try {
    const dbs = await listDatabases()
    if (dbs.some(db => db.name === name)) return true

    if (name.length > 0 && name.length < 64 &&
        !name.includes('/') && !name.includes(':')) {
      const dbPatterns = [
        /^sample_/,
        /^test/,
        /^db/,
        /^admin$|^local$|^config$/
      ]

      if (dbPatterns.some(pattern => pattern.test(name))) return true
    }

    return false
  } catch (error) {
    return false
  }
}

const listDatabases = async () => {
  log('DB Operation: Listing databases…')
  const adminDb = mongoClient.db('admin')
  const result = await adminDb.admin().listDatabases()
  log(`DB Operation: Found ${result.databases.length} databases.`)
  return result.databases
}

const createDatabase = async (dbName, validateName = true) => {
  log(`DB Operation: Creating database '${dbName}'…`)
  if (validateName.toLowerCase() === 'true' && config.security.strictDatabaseNameValidation) {
    const invalidChars = /[\/\\.\s"$*<>:|?]/
    if (invalidChars.test(dbName)) {
      throw new Error(`Invalid database name: '${dbName}'. Database names cannot contain spaces or special characters like /, \\, ., ", $, *, <, >, :, |, ?`)
    }
    if (dbName.length > 63) {
      throw new Error(`Invalid database name: '${dbName}'. Database names must be shorter than 64 characters.`)
    }
  }

  const db = mongoClient.db(dbName)
  const metadataCollectionName = 'metadata'
  const timestamp = new Date()
  const serverInfo = await mongoClient.db('admin').command({ buildInfo: 1 }).catch(() => ({ version: 'Unknown' }))
  const clientInfo = await mongoClient.db('admin').command({ connectionStatus: 1 }).catch(() => ({ authInfo: { authenticatedUsers: [] } }))
  const metadata = {
    created: {
      timestamp,
      tool: `MongoDB Lens v${getPackageVersion()}`,
      user: clientInfo.authInfo?.authenticatedUsers[0]?.user || 'anonymous'
    },
    mongodb: {
      version: serverInfo.version,
      connectionInfo: {
        host: mongoClient.s?.options?.hosts?.map(h => `${h.host}:${h.port}`).join(',') || 'unknown',
        readPreference: mongoClient.s?.readPreference?.mode || 'primary'
      }
    },
    database: {
      name: dbName,
      description: 'Created via MongoDB Lens'
    },
    system: {
      hostname: process.env.HOSTNAME || 'unknown',
      platform: process.platform,
      nodeVersion: process.version
    },
    lens: {
      version: getPackageVersion(),
      startTimestamp: new Date(Date.now() - (process.uptime() * 1000))
    }
  }

  try {
    await db.createCollection(metadataCollectionName)
    await db.collection(metadataCollectionName).insertOne(metadata)
    log(`Tool: Database '${dbName}' created successfully with metadata collection.`)
  } catch (error) {
    log(`Warning: Created database '${dbName}' but metadata insertion failed: ${error.message}`, true)
  }

  return db
}

const switchDatabase = async (dbName) => {
  log(`DB Operation: Switching to database '${dbName}'…`)
  try {
    if (config.security.strictDatabaseNameValidation) {
      const invalidChars = /[\/\\.\s"$*<>:|?]/
      if (invalidChars.test(dbName)) {
        throw new Error(`Invalid database name: '${dbName}'. Database names cannot contain spaces or special characters like /, \\, ., ", $, *, <, >, :, |, ?`)
      }
      if (dbName.length > 63) {
        throw new Error(`Invalid database name: '${dbName}'. Database names must be shorter than 64 characters.`)
      }
    }

    const dbs = await listDatabases()
    const dbExists = dbs.some(db => db.name === dbName)
    if (!dbExists) throw new Error(`Database '${dbName}' does not exist`)
    currentDbName = dbName
    currentDb = mongoClient.db(dbName)

    await setProfilerSlowMs()

    log(`DB Operation: Successfully switched to database '${dbName}'.`)
    return currentDb
  } catch (error) {
    log(`DB Operation: Failed to switch to database '${dbName}': ${error.message}`)
    throw error
  }
}

const dropDatabase = async (dbName) => {
  log(`DB Operation: Dropping database '${dbName}'…`)
  if (dbName.toLowerCase() === 'admin') throw new Error(`Dropping the 'admin' database is prohibited.`)
  try {
    const wasConnected = currentDbName === dbName
    const db = mongoClient.db(dbName)
    await db.dropDatabase()
    if (wasConnected) {
      currentDbName = 'admin'
      currentDb = mongoClient.db('admin')
      log(`DB Operation: Switched to 'admin' database after dropping '${dbName}'`)
    }
    log(`DB Operation: Database '${dbName}' dropped successfully.`)

    const message = `Database '${dbName}' has been permanently deleted.${
      wasConnected ? '\n\nYou were previously connected to this database, you have been automatically switched to the \'admin\' database.' : ''
    }`

    return { success: true, name: dbName, message }
  } catch (error) {
    log(`DB Operation: Database drop failed: ${error.message}`)
    throw error
  }
}

const createUser = async (username, password, roles) => {
  log(`DB Operation: Creating user '${username}' with roles: ${JSON.stringify(roles)}…`)
  try {
    await currentDb.command({
      createUser: username,
      pwd: password,
      roles: roles
    })
    log(`DB Operation: User created successfully.`)
  } catch (error) {
    log(`DB Operation: Failed to create user: ${error.message}`)
    throw error
  }
}

const dropUser = async (username) => {
  log(`DB Operation: Dropping user '${username}'…`)
  try {
    await currentDb.command({
      dropUser: username
    })
    log(`DB Operation: User dropped successfully.`)
  } catch (error) {
    log(`DB Operation: Failed to drop user: ${error.message}`)
    throw error
  }
}

const throwIfCollectionNotExists = async (collectionName) => {
  if (!await collectionExists(collectionName)) {
    throw new Error(`Collection '${collectionName}' does not exist`)
  }
}

const collectionExists = async (collectionName) => {
  if (!currentDb) throw new Error('No database selected')
  const collections = await currentDb.listCollections().toArray()
  return collections.some(coll => coll.name === collectionName)
}

const listCollections = async () => {
  log(`DB Operation: Listing collections in database '${currentDbName}'…`)
  try {
    if (!currentDb) throw new Error('No database selected')

    const cacheKey = currentDbName
    const cachedData = memoryCache.collections.get(cacheKey)

    if (cachedData && (Date.now() - cachedData.timestamp) < config.cacheTTL.collections) {
      log(`DB Operation: Using cached collections list for '${currentDbName}'`)
      return cachedData.data
    }

    const collections = await currentDb.listCollections().toArray()
    log(`DB Operation: Found ${collections.length} collections.`)

    memoryCache.collections.set(cacheKey, {
      data: collections,
      timestamp: Date.now()
    })

    return collections
  } catch (error) {
    log(`DB Operation: Failed to list collections: ${error.message}`)
    throw error
  }
}

const validateCollection = async (collectionName, full = false) => {
  log(`DB Operation: Validating collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const result = await currentDb.command({ validate: collectionName, full })
    if (!result) throw new Error(`Validation returned no result`)
    log(`DB Operation: Collection validation complete.`)
    return result
  } catch (error) {
    log(`DB Operation: Collection validation failed: ${error.message}`)
    throw error
  }
}

const createCollection = async (name, options = {}) => {
  log(`DB Operation: Creating collection '${name}'…`)
  try {
    const result = await currentDb.createCollection(name, options)

    if (result === true) return { success: true, name }
    if (result && result.ok === 1) return { success: true, name }
    if (result && result.collectionName === name) return { success: true, name }

    const errorMsg = "Collection creation did not return a valid collection"
    log(`DB Operation: Collection creation failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Collection creation failed: ${error.message}`)
    throw error
  }
}

const dropCollection = async (name) => {
  log(`DB Operation: Dropping collection '${name}'…`)
  try {
    const result = await currentDb.collection(name).drop()

    if (result === true) return { success: true, name }
    if (result && result.ok === 1) return { success: true, name }
    if (result && result.dropped === name) return { success: true, name }

    const errorMsg = "Collection drop operation did not return success"
    log(`DB Operation: Collection drop failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Collection drop failed: ${error.message}`)
    throw error
  }
}

const renameCollection = async (oldName, newName, dropTarget = false) => {
  log(`DB Operation: Renaming collection from '${oldName}' to '${newName}'…`)
  try {
    const result = await currentDb.collection(oldName).rename(newName, { dropTarget })

    if (result === true) return { success: true, oldName, newName }
    if (result && result.ok === 1) return { success: true, oldName, newName }
    if (result && result.collectionName === newName) return { success: true, oldName, newName }

    const errorMsg = "Collection rename did not return a valid result"
    log(`DB Operation: Collection rename failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Collection rename failed: ${error.message}`)
    throw error
  }
}

const getCollectionStats = async (collectionName) => {
  log(`DB Operation: Getting statistics for collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)

    const adminDb = mongoClient.db('admin')
    let serverInfo
    try {
      serverInfo = await adminDb.command({ buildInfo: 1 })
    } catch (verError) {
      log(`DB Operation: Warning: Unable to determine server version: ${verError.message}`)
      serverInfo = { version: '0.0.0' }
    }

    const versionParts = serverInfo.version.split('.').map(Number)
    const isVersion4Plus = versionParts[0] >= 4

    const statsCmd = isVersion4Plus
      ? { collStats: collectionName, scale: 1 }
      : { collStats: collectionName }

    const stats = await currentDb.command(statsCmd)
    const normalizedStats = { ...stats }

    if (stats.wiredTiger && isVersion4Plus) {
      normalizedStats.wiredTigerVersion = stats.wiredTiger.creationString || 'unknown'
    }

    log(`DB Operation: Retrieved statistics for collection '${collectionName}'.`)
    return normalizedStats
  } catch (error) {
    log(`DB Operation: Failed to get statistics for collection '${collectionName}': ${error.message}`)
    throw error
  }
}

const getCollectionIndexes = async (collectionName) => {
  log(`DB Operation: Getting indexes for collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)

    const cacheKey = `${currentDbName}.${collectionName}`
    const cachedData = memoryCache.indexes.get(cacheKey)

    if (cachedData && (Date.now() - cachedData.timestamp) < config.cacheTTL.stats) {
      log(`DB Operation: Using cached indexes for '${collectionName}'`)
      return cachedData.data
    }

    const indexes = await currentDb.collection(collectionName).indexes()
    log(`DB Operation: Retrieved ${indexes.length} indexes for collection '${collectionName}'.`)

    try {
      const stats = await currentDb.command({ collStats: collectionName, indexDetails: true })
      if (stats && stats.indexDetails) {
        for (const index of indexes) {
          if (stats.indexDetails[index.name]) {
            index.usage = stats.indexDetails[index.name]
          }
        }
      }
    } catch (statsError) {
      log(`DB Operation: Index usage stats not available: ${statsError.message}`)
    }

    memoryCache.indexes.set(cacheKey, {
      data: indexes,
      timestamp: Date.now()
    })

    return indexes
  } catch (error) {
    log(`DB Operation: Failed to get indexes for collection '${collectionName}': ${error.message}`)
    throw error
  }
}

const findDocuments = async (collectionName, filter = {}, projection = null, limit = config.defaults.queryLimit, skip = 0, sort = null) => {
  log(`DB Operation: Finding documents in collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)
    let query = collection.find(filter)

    if (projection) query = query.project(projection)
    if (skip) query = query.skip(skip)
    if (limit) query = query.limit(limit)
    if (sort) query = query.sort(sort)

    const results = await query.toArray()
    log(`DB Operation: Found ${results.length} documents.`)
    return results
  } catch (error) {
    log(`DB Operation: Failed to find documents: ${error.message}`)
    throw error
  }
}

const countDocuments = async (collectionName, filter = {}) => {
  log(`DB Operation: Counting documents in collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)
    const count = await collection.countDocuments(filter)
    log(`DB Operation: Count result: ${count} documents.`)
    return count
  } catch (error) {
    log(`DB Operation: Failed to count documents: ${error.message}`)
    throw error
  }
}

const insertDocument = async (collectionName, document, options = {}) => {
  log(`DB Operation: Inserting document(s) into collection '${collectionName}'…`)
  try {
    const collection = currentDb.collection(collectionName)

    if (Array.isArray(document)) {
      const result = await collection.insertMany(document, options)

      if (result && result.ops && Array.isArray(result.ops)) {
        return {
          acknowledged: true,
          insertedCount: result.insertedCount || result.ops.length,
          insertedIds: result.insertedIds || result.ops.reduce((ids, doc, i) => {
            ids[i] = doc._id || 'unknown'
            return ids
          }, {})
        }
      }

      if (result === document.length || result === true) return {
        acknowledged: true,
        insertedCount: document.length,
        insertedIds: document.reduce((ids, doc, i) => {
          ids[i] = doc._id || 'unknown'
          return ids
        }, {})
      }

      if (result && typeof result.insertedCount === 'number') return result

      if (result && result.result && result.result.ok === 1) return {
        acknowledged: true,
        insertedCount: result.result.n || document.length,
        insertedIds: result.insertedIds || {}
      }

      return {
        acknowledged: true,
        insertedCount: document.length,
        insertedIds: {}
      }
    }

    const result = await collection.insertOne(document, options)

    if (result === 1 || result === true) return { acknowledged: true, insertedId: document._id || 'unknown' }

    if (result && result.insertedCount === 1)
      return {
        acknowledged: true,
        insertedId: result.insertedId || result.ops?.[0]?._id || document._id
      }

    if (result && result.acknowledged && result.insertedId) return result

    if (result && result.result && result.result.ok === 1)
      return {
        acknowledged: true,
        insertedId: result.insertedId || document._id,
        insertedCount: result.result.n || 1
      }

    const errorMsg = "Insert operation failed or was not acknowledged by MongoDB"
    log(`DB Operation: Document insertion failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Document insertion failed: ${error.message}`)
    throw error
  }
}

const updateDocument = async (collectionName, filter, update, options = {}) => {
  log(`DB Operation: Updating document(s) in collection '${collectionName}'…`)
  try {
    const collection = currentDb.collection(collectionName)
    const hasUpdateOperators = Object.keys(update).some(key => key.startsWith('$'))

    if (!hasUpdateOperators) update = { $set: update }

    let result
    if (options.multi === true || options.many === true) {
      result = await collection.updateMany(filter, update, options)
    } else {
      result = await collection.updateOne(filter, update, options)
    }

    if (result === 1 || result === true) return { acknowledged: true, matchedCount: 1, modifiedCount: 1 }

    if (result && typeof result.modifiedCount === 'number') return result

    if (result && result.result && result.result.ok === 1)
      return {
        acknowledged: true,
        matchedCount: result.result.n || 0,
        modifiedCount: result.result.nModified || 0,
        upsertedId: result.upsertedId || null
      }

    if (result && result.acknowledged !== false)
      return {
        acknowledged: true,
        matchedCount: result.n || result.matchedCount || 0,
        modifiedCount: result.nModified || result.modifiedCount || 0
      }

    const errorMsg = "Update operation failed or was not acknowledged by MongoDB"
    log(`DB Operation: Document update failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Document update failed: ${error.message}`)
    throw error
  }
}

const deleteDocument = async (collectionName, filter, options = {}) => {
  log(`DB Operation: Deleting document(s) from collection '${collectionName}'…`)
  try {
    const collection = currentDb.collection(collectionName)

    let result
    if (options.many === true) {
      result = await collection.deleteMany(filter, options)
    } else {
      result = await collection.deleteOne(filter, options)
    }

    if (result === 1 || result === true) return { acknowledged: true, deletedCount: 1 }

    if (result && typeof result.deletedCount === 'number') return result

    if (result && result.result && result.result.ok === 1) return { acknowledged: true, deletedCount: result.result.n || 0 }

    if (result && result.acknowledged !== false) return {acknowledged: true, deletedCount: result.n || 0 }

    const errorMsg = "Delete operation failed or was not acknowledged by MongoDB"
    log(`DB Operation: Document deletion failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Document deletion failed: ${error.message}`)
    throw error
  }
}

const aggregateData = async (collectionName, pipeline) => {
  log(`DB Operation: Running aggregation on collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    log(`DB Operation: Pipeline has ${pipeline.length} stages.`)
    const collection = currentDb.collection(collectionName)
    const cursor = collection.aggregate(pipeline, { allowDiskUse: config.defaults.allowDiskUse })
    let results
    if (cursor && typeof cursor.toArray === 'function') results = await cursor.toArray()
    else if (cursor && cursor.result) results = cursor.result
    else if (Array.isArray(cursor)) results = cursor
    else results = cursor || []

    log(`DB Operation: Aggregation returned ${results.length} results.`)
    return results
  } catch (error) {
    log(`DB Operation: Failed to run aggregation: ${error.message}`)
    throw error
  }
}

const getDatabaseStats = async () => {
  log(`DB Operation: Getting statistics for database '${currentDbName}'…`)
  const stats = await currentDb.stats()
  log(`DB Operation: Retrieved database statistics.`)
  return stats
}

const inferSchema = async (collectionName, sampleSize = config.defaults.schemaSampleSize) => {
  log(`DB Operation: Inferring schema for collection '${collectionName}' with sample size ${sampleSize}…`)
  try {
    await throwIfCollectionNotExists(collectionName)

    const cacheKey = `${currentDbName}.${collectionName}.${sampleSize}`
    const cachedSchema = memoryCache.schemas.get(cacheKey)

    if (cachedSchema && (Date.now() - cachedSchema.timestamp) < config.cacheTTL.schemas) {
      log(`DB Operation: Using cached schema for '${collectionName}'`)
      return cachedSchema.data
    }

    const collection = currentDb.collection(collectionName)

    const pipeline = [{ $sample: { size: sampleSize } }]

    const cursor = collection.aggregate(pipeline, {
      allowDiskUse: config.defaults.allowDiskUse,
      cursor: { batchSize: config.defaults.aggregationBatchSize }
    })

    const documents = []
    const fieldPaths = new Set()
    const schema = {}
    let processed = 0

    for await (const doc of cursor) {
      documents.push(doc)
      collectFieldPaths(doc, '', fieldPaths)
      processed++
      if (processed % 50 === 0) log(`DB Operation: Processed ${processed} documents for schema inference…`)
    }

    log(`DB Operation: Retrieved ${documents.length} sample documents for schema inference.`)

    if (documents.length === 0) throw new Error(`Collection '${collectionName}' is empty`)

    fieldPaths.forEach(path => {
      schema[path] = {
        types: new Set(),
        count: 0,
        sample: null,
        path: path
      }
    })

    documents.forEach(doc => {
      fieldPaths.forEach(path => {
        const value = getNestedValue(doc, path)
        if (value !== undefined) {
          if (!schema[path].sample) {
            schema[path].sample = value
          }
          schema[path].types.add(getTypeName(value))
          schema[path].count++
        }
      })
    })

    for (const key in schema) {
      schema[key].types = Array.from(schema[key].types)
      schema[key].coverage = Math.round((schema[key].count / documents.length) * 100)
    }

    const result = {
      collectionName,
      sampleSize: documents.length,
      fields: schema,
      timestamp: new Date().toISOString()
    }

    memoryCache.schemas.set(cacheKey, {
      data: result,
      timestamp: Date.now()
    })

    const fieldsArray = Object.keys(schema)
    log(`DB Operation: Schema inference complete, identified ${fieldsArray.length} fields.`)

    memoryCache.fields.set(`${currentDbName}.${collectionName}`, {
      data: fieldsArray,
      timestamp: Date.now()
    })

    return result
  } catch (error) {
    log(`DB Operation: Failed to infer schema: ${error.message}`)
    throw error
  }
}

const collectFieldPaths = (obj, prefix = '', paths = new Set()) => {
  if (!obj || typeof obj !== 'object') return

  Object.entries(obj).forEach(([key, value]) => {
    const path = prefix ? `${prefix}.${key}` : key
    paths.add(path)

    if (value && typeof value === 'object') {
      if (Array.isArray(value)) {
        if (value.length > 0) {
          if (typeof value[0] === 'object' && value[0] !== null) {
            collectFieldPaths(value[0], `${path}[]`, paths)
          }
        }
      } else if (!(value instanceof ObjectId) && !(value instanceof Date)) {
        collectFieldPaths(value, path, paths)
      }
    }
  })

  return paths
}

const getTypeName = (value) => {
  if (value === null) return 'null'
  if (value === undefined) return 'undefined'
  if (Array.isArray(value)) return 'array'
  if (value instanceof ObjectId) return 'ObjectId'
  if (value instanceof Date) return 'Date'
  return typeof value
}

const createIndex = async (collectionName, keys, options = {}) => {
  log(`DB Operation: Creating index on collection '${collectionName}'…`)
  log(`DB Operation: Index keys: ${JSON.stringify(keys)}`)
  if (Object.keys(options).length > 0) log(`DB Operation: Index options: ${JSON.stringify(options)}`)

  try {
    const collection = currentDb.collection(collectionName)
    const result = await collection.createIndex(keys, options)

    if (typeof result === 'string') return result
    if (result && result.name) return result.name
    if (result && result.ok === 1) return result.name || 'index'

    const errorMsg = "Index creation did not return a valid index name"
    log(`DB Operation: Index creation failed: ${errorMsg}`)
    throw new Error(errorMsg)
  } catch (error) {
    log(`DB Operation: Index creation failed: ${error.message}`)
    throw error
  }
}

const dropIndex = async (collectionName, indexName) => {
  log(`DB Operation: Dropping index '${indexName}' from collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)
    const result = await collection.dropIndex(indexName)

    if (result === true) return true
    if (result && result.ok === 1) return true
    if (result && typeof result === 'object') return true
    if (result === undefined || result === null) return true

    log(`DB Operation: Index dropped with unexpected result: ${JSON.stringify(result)}`)
    return true
  } catch (error) {
    log(`DB Operation: Failed to drop index: ${error.message}`)
    throw error
  }
}

const explainQuery = async (collectionName, filter, verbosity = 'executionStats') => {
  log(`DB Operation: Explaining query on collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)
    const explanation = await collection.find(filter).explain(verbosity)
    if (!explanation) throw new Error(`Explain operation returned no result`)
    log(`DB Operation: Query explanation generated.`)
    return explanation
  } catch (error) {
    log(`DB Operation: Query explanation failed: ${error.message}`)
    throw error
  }
}

const getSuggestedProjection = (filter, fields) => {
  if (!fields || fields.length === 0) return null

  const filterFields = new Set(Object.keys(filter))
  const commonFields = new Set(['_id', 'name', 'title', 'date', 'createdAt', 'updatedAt'])

  const projectionFields = {}

  filterFields.forEach(field => {
    if (fields.includes(field)) projectionFields[field] = 1
  })

  fields.forEach(field => {
    if (commonFields.has(field)) projectionFields[field] = 1
  })

  if (Object.keys(projectionFields).length === 0) return null

  return JSON.stringify(projectionFields)
}

const getServerStatus = async () => {
  log('DB Operation: Getting server status…')
  try {
    const cacheKey = 'server_status'
    const cachedData = memoryCache.serverStatus.get(cacheKey)

    if (cachedData && (Date.now() - cachedData.timestamp) < config.cacheTTL.serverStatus) {
      log('DB Operation: Using cached server status')
      return cachedData.data
    }

    const adminDb = mongoClient.db('admin')
    const status = await adminDb.command({ serverStatus: 1 })

    const versionParts = status.version ? status.version.split('.').map(Number) : [0, 0]
    const versionDetails = {
      major: versionParts[0] || 0,
      minor: versionParts[1] || 0,
      isV3OrLower: (versionParts[0] || 0) <= 3,
      isV4: (versionParts[0] || 0) === 4,
      isV5OrHigher: (versionParts[0] || 0) >= 5
    }

    const normalizedStatus = { ...status, versionDetails }

    if (versionDetails.isV5OrHigher && !normalizedStatus.wiredTiger && normalizedStatus.wiredTiger3) {
      normalizedStatus.wiredTiger = normalizedStatus.wiredTiger3
    }

    memoryCache.serverStatus.set(cacheKey, {
      data: normalizedStatus,
      timestamp: Date.now()
    })

    log('DB Operation: Retrieved and normalized server status.')
    return normalizedStatus
  } catch (error) {
    log(`DB Operation: Error getting server status: ${error.message}`)
    return {
      host: mongoClient.s?.options?.host || mongoClient.s?.options?.hosts?.[0]?.host || 'unknown',
      port: mongoClient.s?.options?.port || mongoClient.s?.options?.hosts?.[0]?.port || 'unknown',
      version: 'Information unavailable',
      error: error.message
    }
  }
}

const getReplicaSetStatus = async () => {
  log('DB Operation: Getting replica set status…')
  try {
    const adminDb = mongoClient.db('admin')
    const status = await adminDb.command({ replSetGetStatus: 1 })
    log('DB Operation: Retrieved replica set status.')
    return status
  } catch (error) {
    log(`DB Operation: Error getting replica set status: ${error.message}`)
    return {
      isReplicaSet: false,
      info: 'This server is not part of a replica set or you may not have permissions to view replica set status.',
      error: error.message,
      replicaSetRequired: true
    }
  }
}

const getCollectionValidation = async (collectionName) => {
  log(`DB Operation: Getting validation rules for collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collections = await currentDb.listCollections({ name: collectionName }, { validator: 1 }).toArray()
    log(`DB Operation: Retrieved validation information for collection '${collectionName}'.`)
    if (collections.length === 0) return { hasValidation: false }
    return {
      hasValidation: !!collections[0].options?.validator,
      validator: collections[0].options?.validator || {},
      validationLevel: collections[0].options?.validationLevel || 'strict',
      validationAction: collections[0].options?.validationAction || 'error'
    }
  } catch (error) {
    log(`DB Operation: Error getting validation for ${collectionName}: ${error.message}`)
    throw error
  }
}

const getCollectionFields = async (collectionName) => {
  const cacheKey = `${currentDbName}.${collectionName}`
  const cachedData = memoryCache.fields.get(cacheKey)

  if (cachedData && (Date.now() - cachedData.timestamp) < config.cacheTTL.fields) {
    log(`DB Operation: Using cached fields for '${collectionName}'`)
    return cachedData.data
  }

  const schema = await inferSchema(collectionName, 10)
  const fieldsArray = Object.keys(schema.fields)

  memoryCache.fields.set(cacheKey, {
    data: fieldsArray,
    timestamp: Date.now()
  })

  return fieldsArray
}

const setProfilerSlowMs = async () => {
  try {
    await currentDb.command({ profile: -1 })
    await currentDb.command({ profile: 0, slowms: config.defaults.slowMs })
    log(`DB Operation: Set slow query threshold to ${config.defaults.slowMs}ms`)
    return true
  } catch (error) {
    log(`Error setting profiler: ${error.message}`)
    return false
  }
}

const runTransaction = async (operations) => {
  try {
    log('Tool: Executing operations in a transaction…')

    try {
      const session = mongoClient.startSession()
      await session.endSession()
    } catch (error) {
      if (error.message.includes('not supported') ||
          error.message.includes('requires replica set') ||
          error.codeName === 'NotAReplicaSet') {
        return {
          content: [{
            type: 'text',
            text: `Transactions are not supported on your MongoDB deployment.\n\nTransactions require MongoDB to be running as a replica set or sharded cluster. You appear to be running a standalone server.\n\nAlternative: You can set up a single-node replica set for development purposes by following these steps:\n\n1. Stop your MongoDB server\n2. Start it with the --replSet option: \`mongod --replSet rs0\`\n3. Connect to it and initialize the replica set: \`rs.initiate()\`\n\nThen try the transaction tool again.`
          }]
        }
      }
      throw error
    }

    const parsedOps = JSON.parse(operations)
    const session = mongoClient.startSession()
    let results = []

    try {
      session.startTransaction({
        readConcern: { level: config.tools.transaction.readConcern },
        writeConcern: config.tools.transaction.writeConcern
      })

      for (let i = 0; i < parsedOps.length; i++) {
        const op = parsedOps[i]
        log(`Tool: Transaction step ${i+1}: ${op.operation} on ${op.collection}`)

        let result
        const collection = currentDb.collection(op.collection)

        if (op.operation === 'insert') {
          result = await collection.insertOne(op.document, { session })
        } else if (op.operation === 'update') {
          result = await collection.updateOne(op.filter, op.update, { session })
        } else if (op.operation === 'delete') {
          result = await collection.deleteOne(op.filter, { session })
        } else if (op.operation === 'find') {
          result = await collection.findOne(op.filter, { session })
        } else {
          throw new Error(`Unsupported operation: ${op.operation}`)
        }

        results.push({ step: i+1, operation: op.operation, result })
      }

      await session.commitTransaction()
      log('Tool: Transaction committed successfully')
    } catch (error) {
      await session.abortTransaction()
      log(`Tool: Transaction aborted due to error: ${error.message}`)
      throw error
    } finally {
      await session.endSession()
    }

    return {
      content: [{
        type: 'text',
        text: formatTransactionResults(results)
      }]
    }
  } catch (error) {
    return {
      content: [{
        type: 'text',
        text: `Error executing transaction: ${error.message}`
      }],
      isError: true
    }
  }
}

const getDatabaseUsers = async () => {
  log(`DB Operation: Getting users for database '${currentDbName}'…`)
  try {
    const users = await currentDb.command({ usersInfo: 1 })
    log(`DB Operation: Retrieved user information.`)
    return users
  } catch (error) {
    log(`DB Operation: Error getting users: ${error.message}`)
    return {
      users: [],
      info: 'Could not retrieve user information. You may not have sufficient permissions.',
      error: error.message
    }
  }
}

const getStoredFunctions = async () => {
  log(`DB Operation: Getting stored JavaScript functions…`)
  try {
    const system = currentDb.collection('system.js')
    const functions = await system.find({}).toArray()
    log(`DB Operation: Retrieved ${functions.length} stored functions.`)
    return functions
  } catch (error) {
    log(`DB Operation: Error getting stored functions: ${error.message}`)
    return []
  }
}

const getPerformanceMetrics = async () => {
  try {
    await setProfilerSlowMs()

    const adminDb = mongoClient.db('admin')
    const serverStatus = await adminDb.command({ serverStatus: 1 })
    const profileStats = await currentDb.command({ profile: -1 })

    const currentOps = await adminDb.command({
      currentOp: 1,
      active: true,
      secs_running: { $gt: 1 }
    })

    const perfStats = await currentDb.command({ dbStats: 1 })

    const slowQueries = await currentDb.collection('system.profile')
      .find({ millis: { $gt: config.defaults.slowMs } })
      .sort({ ts: -1 })
      .limit(10)
      .toArray()

    return {
      serverStatus: {
        connections: serverStatus.connections,
        network: serverStatus.network,
        opcounters: serverStatus.opcounters,
        wiredTiger: serverStatus.wiredTiger?.cache,
        mem: serverStatus.mem,
        locks: serverStatus.locks
      },
      profileSettings: profileStats,
      currentOperations: currentOps.inprog,
      performance: perfStats,
      slowQueries
    }
  } catch (error) {
    log(`Error getting performance metrics: ${error.message}`)
    return { error: error.message }
  }
}

const getDatabaseTriggers = async () => {
  try {
    try {
      const coll = currentDb.collection('system.version')
      const testStream = coll.watch()
      await testStream.close()

      const changeStreamInfo = {
        supported: true,
        resumeTokenSupported: true,
        updateLookupSupported: true,
        fullDocumentBeforeChangeSupported: true
      }

      const triggerCollections = await currentDb.listCollections({ name: /trigger|event|notification/i }).toArray()
      const system = currentDb.collection('system.js')
      const triggerFunctions = await system.find({ _id: /trigger|event|watch|notify/i }).toArray()

      return {
        changeStreams: changeStreamInfo,
        triggerCollections,
        triggerFunctions
      }
    } catch (error) {
      if (error.code === 40573 || error.message.includes('only supported on replica sets')) {
        return {
          changeStreams: {
            supported: false,
            reason: "Change streams require a replica set or sharded cluster",
            howToEnable: "To enable change streams for development, configure MongoDB as a single-node replica set"
          },
          triggerCollections: [],
          triggerFunctions: []
        }
      }
      throw error
    }
  } catch (error) {
    log(`Error getting database triggers: ${error.message}`)
    return {
      error: error.message,
      supported: false
    }
  }
}

const getDistinctValues = async (collectionName, field, filter = {}) => {
  log(`DB Operation: Getting distinct values for field '${field}' in collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    if (!isValidFieldName(field)) throw new Error(`Invalid field name: ${field}`)
    const collection = currentDb.collection(collectionName)
    const values = await collection.distinct(field, filter)
    log(`DB Operation: Found ${values.length} distinct values.`)
    return values
  } catch (error) {
    log(`DB Operation: Failed to get distinct values: ${error.message}`)
    throw error
  }
}

const isValidFieldName = (field) =>
  typeof field === 'string' && field.length > 0 && !field.startsWith('$')

const runMapReduce = async (collectionName, map, reduce, options = {}) => {
  log(`DB Operation: Running Map-Reduce on collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)

    if (!options.out) options.out = { inline: 1 }

    const results = await collection.mapReduce(map, reduce, options)

    if (results && typeof results.toArray === 'function') {
      log(`DB Operation: Map-Reduce operation complete (legacy mode).`)
      return results.toArray()
    } else if (results && Array.isArray(results)) {
      log(`DB Operation: Map-Reduce operation complete (array results).`)
      return results
    } else if (results && options.out && options.out.inline !== 1) {
      log(`DB Operation: Map-Reduce output to collection '${typeof options.out === 'string' ? options.out : JSON.stringify(options.out)}'.`)
      const outCollection = currentDb.collection(
        typeof options.out === 'string' ? options.out : options.out.replace
      )
      return outCollection.find().toArray()
    } else {
      log(`DB Operation: Map-Reduce operation complete (unknown format).`)
      return Array.isArray(results) ? results : (results.result || results)
    }
  } catch (error) {
    log(`DB Operation: Map-Reduce operation failed: ${error.message}`)
    throw error
  }
}

const bulkOperations = async (collectionName, operations, ordered = config.tools.bulkOperations.ordered) => {
  log(`DB Operation: Performing bulk operations on collection '${collectionName}'…`)
  try {
    await throwIfCollectionNotExists(collectionName)
    const collection = currentDb.collection(collectionName)

    let bulk
    try {
      bulk = ordered ? collection.initializeOrderedBulkOp() : collection.initializeUnorderedBulkOp()
    } catch (bulkError) {
      log(`DB Operation: Modern bulk API unavailable, trying legacy method: ${bulkError.message}`)
      if (typeof collection.bulkWrite === 'function') {
        const result = await collection.bulkWrite(operations, { ordered })
        log(`DB Operation: Bulk operations complete (using bulkWrite).`)
        return normalizeBulkResult(result)
      } else {
        throw new Error('Bulk operations not supported by this MongoDB version/driver')
      }
    }

    for (const op of operations) {
      if (op.insertOne) bulk.insert(op.insertOne.document)
      else if (op.updateOne) bulk.find(op.updateOne.filter).updateOne(op.updateOne.update)
      else if (op.updateMany) bulk.find(op.updateMany.filter).update(op.updateMany.update)
      else if (op.deleteOne) bulk.find(op.deleteOne.filter).deleteOne()
      else if (op.deleteMany) bulk.find(op.deleteMany.filter).delete()
      else if (op.replaceOne) bulk.find(op.replaceOne.filter).replaceOne(op.replaceOne.replacement)
    }

    const result = await bulk.execute()
    log(`DB Operation: Bulk operations complete.`)
    return normalizeBulkResult(result)
  } catch (error) {
    log(`DB Operation: Bulk operations failed: ${error.message}`)
    throw error
  }
}

const normalizeBulkResult = (result) => {
  if (!result) return { acknowledged: false }

  if (typeof result.insertedCount === 'number' ||
      typeof result.matchedCount === 'number' ||
      typeof result.deletedCount === 'number') {
    return {
      acknowledged: true,
      insertedCount: result.insertedCount || 0,
      matchedCount: result.matchedCount || 0,
      modifiedCount: result.modifiedCount || 0,
      deletedCount: result.deletedCount || 0,
      upsertedCount: result.upsertedCount || 0,
      upsertedIds: result.upsertedIds || {},
      insertedIds: result.insertedIds || {}
    }
  }

  if (result.ok === 1 || (result.result && result.result.ok === 1)) {
    const nInserted = result.nInserted || result.result?.nInserted || 0
    const nMatched = result.nMatched || result.result?.nMatched || 0
    const nModified = result.nModified || result.result?.nModified || 0
    const nUpserted = result.nUpserted || result.result?.nUpserted || 0
    const nRemoved = result.nRemoved || result.result?.nRemoved || 0

    return {
      acknowledged: true,
      insertedCount: nInserted,
      matchedCount: nMatched,
      modifiedCount: nModified,
      deletedCount: nRemoved,
      upsertedCount: nUpserted,
      upsertedIds: result.upserted || result.result?.upserted || {},
      insertedIds: {}
    }
  }

  if (typeof result === 'number') {
    return {
      acknowledged: true,
      insertedCount: 0,
      matchedCount: 0,
      modifiedCount: 0,
      deletedCount: 0,
      upsertedCount: 0,
      result: { n: result }
    }
  }

  return { acknowledged: false }
}

const getShardingDbStatus = async (dbName) => {
  try {
    const config = mongoClient.db('config')
    return await config.collection('databases').findOne({ _id: dbName })
  } catch (error) {
    log(`Error getting database sharding status: ${error.message}`)
    return null
  }
}

const getShardingCollectionStatus = async (dbName, collName) => {
  try {
    const config = mongoClient.db('config')
    return await config.collection('collections').findOne({ _id: `${dbName}.${collName}` })
  } catch (error) {
    log(`Error getting collection sharding status: ${error.message}`)
    return null
  }
}

const formatDatabasesList = (databases) => {
  return `Databases (${databases.length}):\n` +
    databases.map(db => `- ${db.name} (${formatSize(db.sizeOnDisk)})`).join('\n')
}

const formatCollectionsList = (collections) => {
  if (!collections || collections.length === 0) {
    return `No collections found in database '${currentDbName}'`
  }

  return `Collections in ${currentDbName} (${collections.length}):\n` +
    collections.map(coll => `- ${coll.name} (${coll.type})`).join('\n')
}

const formatDocuments = (documents, limit) => {
  if (!documents || documents.length === 0) {
    return 'No documents found'
  }

  const count = documents.length
  let result = `${count} document${count === 1 ? '' : 's'}`
  if (count === limit) {
    result += ` (limit: ${limit})`
  }
  result += ':\n'

  result += documents.map(doc => JSON.stringify(serializeDocument(doc), null, 2)).join('\n\n')
  return result
}

const formatSchema = (schema) => {
  const { collectionName, sampleSize, fields } = schema
  let result = `Schema for '${collectionName}' (sampled ${sampleSize} documents):\n`

  for (const [field, info] of Object.entries(fields)) {
    const types = info.types.join(' | ')
    const coverage = Math.round((info.count / sampleSize) * 100)
    let sample = ''

    if (info.sample !== null && info.sample !== undefined) {
      if (typeof info.sample === 'object') {
        sample = JSON.stringify(serializeDocument(info.sample))
      } else {
        sample = String(info.sample)
      }

      if (sample.length > 50) {
        sample = sample.substring(0, 47) + '…'
      }

      sample = ` (example: ${sample})`
    }

    result += `- ${field}: ${types} (${coverage}% coverage)${sample}\n`
  }

  return result
}

const formatStats = (stats) => {
  if (!stats) return 'No statistics available'

  const keyMetrics = [
    ['ns', 'Namespace'],
    ['count', 'Document Count'],
    ['size', 'Data Size'],
    ['avgObjSize', 'Average Object Size'],
    ['storageSize', 'Storage Size'],
    ['totalIndexSize', 'Total Index Size'],
    ['nindexes', 'Number of Indexes']
  ]

  let result = 'Statistics:\n'

  for (const [key, label] of keyMetrics) {
    if (stats[key] !== undefined) {
      let value = stats[key]
      if (key.toLowerCase().includes('size')) {
        value = formatSize(value)
      }
      result += `- ${label}: ${value}\n`
    }
  }

  return result
}

const formatIndexes = (indexes) => {
  if (!indexes || indexes.length === 0) {
    return 'No indexes found'
  }

  let result = `Indexes (${indexes.length}):\n`

  for (const idx of indexes) {
    const keys = Object.entries(idx.key)
      .map(([field, direction]) => `${field}: ${direction}`)
      .join(', ')

    result += `- ${idx.name}: { ${keys} }`

    if (idx.unique) result += ' (unique)'
    if (idx.sparse) result += ' (sparse)'
    if (idx.background) result += ' (background)'

    result += '\n'
  }

  return result
}

const formatExplanation = (explanation) => {
  let result = 'Query Explanation:\n'

  if (explanation.queryPlanner) {
    result += '\nQuery Planner:\n'
    result += `- Namespace: ${explanation.queryPlanner.namespace}\n`
    result += `- Index Filter: ${JSON.stringify(explanation.queryPlanner.indexFilterSet) || 'None'}\n`
    result += `- Winning Plan: ${JSON.stringify(explanation.queryPlanner.winningPlan, null, 2)}\n`
  }

  if (explanation.executionStats) {
    result += '\nExecution Stats:\n'
    result += `- Execution Success: ${explanation.executionStats.executionSuccess}\n`
    result += `- Documents Examined: ${explanation.executionStats.totalDocsExamined}\n`
    result += `- Keys Examined: ${explanation.executionStats.totalKeysExamined}\n`
    result += `- Execution Time: ${explanation.executionStats.executionTimeMillis}ms\n`
  }

  return result
}

const formatServerStatus = (status) => {
  if (!status) return 'Server status information not available'

  let result = 'MongoDB Server Status:\n'

  if (status.error) {
    result += `Note: Limited information available. ${status.error}\n\n`
  }

  result += '## Server Information\n'
  result += `- Host: ${status.host || 'Unknown'}\n`
  result += `- Version: ${status.version || 'Unknown'}\n`
  result += `- Process: ${status.process || 'Unknown'}\n`
  result += `- Uptime: ${formatUptime(status.uptime)}\n`

  if (status.connections) {
    result += '\n## Connections\n'
    result += `- Current: ${status.connections.current}\n`
    result += `- Available: ${status.connections.available}\n`
    result += `- Total Created: ${status.connections.totalCreated}\n`
  }

  if (status.mem) {
    result += '\n## Memory Usage\n'
    result += `- Resident: ${formatSize(status.mem.resident * 1024 * 1024)}\n`
    result += `- Virtual: ${formatSize(status.mem.virtual * 1024 * 1024)}\n`
    result += `- Page Faults: ${status.extra_info?.page_faults || 'N/A'}\n`
  }

  if (status.opcounters) {
    result += '\n## Operation Counters\n'
    result += `- Insert: ${status.opcounters.insert}\n`
    result += `- Query: ${status.opcounters.query}\n`
    result += `- Update: ${status.opcounters.update}\n`
    result += `- Delete: ${status.opcounters.delete}\n`
    result += `- Getmore: ${status.opcounters.getmore}\n`
    result += `- Command: ${status.opcounters.command}\n`
  }

  return result
}

const formatReplicaSetStatus = (status) => {
  if (!status) return 'Replica set status information not available'

  if (status.error) {
    if (status.replicaSetRequired) {
      return `Replica Set Status: Not available\n\n${status.info}\n\nYou can set up a single-node replica set for development purposes by following these steps:\n\n1. Stop your MongoDB server\n2. Start it with the --replSet option: \`mongod --replSet rs0\`\n3. Connect to it and initialize the replica set: \`rs.initiate()\``
    }
    return `Replica Set Status: Not available (${status.info})\n\n${status.error}`
  }

  let result = `Replica Set: ${status.set}\n`
  result += `Status: ${status.myState === 1 ? 'PRIMARY' : status.myState === 2 ? 'SECONDARY' : 'OTHER'}\n`
  result += `Current Time: ${new Date(status.date.$date || status.date).toISOString()}\n\n`

  result += '## Members:\n'
  if (status.members) {
    for (const member of status.members) {
      result += `- ${member.name} (${member.stateStr})\n`
      result += `  Health: ${member.health}\n`
      result += `  Uptime: ${formatUptime(member.uptime)}\n`
      if (member.syncingTo) {
        result += `  Syncing to: ${member.syncingTo}\n`
      }
      result += '\n'
    }
  }

  return result
}

const formatValidationRules = (validation) => {
  if (!validation) return 'Validation information not available'

  if (!validation.hasValidation) {
    return 'This collection does not have any validation rules configured.'
  }

  let result = 'Collection Validation Rules:\n'
  result += `- Validation Level: ${validation.validationLevel}\n`
  result += `- Validation Action: ${validation.validationAction}\n\n`

  result += 'Validator:\n'
  result += JSON.stringify(validation.validator, null, 2)

  return result
}

const formatDatabaseUsers = (usersInfo) => {
  if (!usersInfo) return 'User information not available'

  if (usersInfo.error) {
    return `Users: Not available\n\n${usersInfo.info}\n${usersInfo.error}`
  }

  const users = usersInfo.users || []
  if (users.length === 0) {
    return 'No users found in the current database.'
  }

  let result = `Users in database '${currentDbName}' (${users.length}):\n\n`

  for (const user of users) {
    result += `## ${user.user}${user.customData ? ' (' + JSON.stringify(user.customData) + ')' : ''}\n`
    result += `- User ID: ${user._id || 'N/A'}\n`
    result += `- Database: ${user.db}\n`

    if (user.roles && user.roles.length > 0) {
      result += '- Roles:\n'
      for (const role of user.roles) {
        result += `  - ${role.role} on ${role.db}\n`
      }
    } else {
      result += '- Roles: None\n'
    }

    result += '\n'
  }

  return result
}

const formatStoredFunctions = (functions) => {
  if (!functions || !Array.isArray(functions)) return 'Stored functions information not available'

  if (functions.length === 0) {
    return 'No stored JavaScript functions found in the current database.'
  }

  let result = `Stored Functions in database '${currentDbName}' (${functions.length}):\n\n`

  for (const func of functions) {
    result += `## ${func._id}\n`

    if (typeof func.value === 'function') {
      result += `${func.value.toString()}\n\n`
    } else {
      result += `${func.value}\n\n`
    }
  }

  return result
}

const formatDistinctValues = (field, values) => {
  if (!values || !Array.isArray(values)) return `No distinct values found for field '${field}'`
  let result = `Distinct values for field '${field}' (${values.length}):\n`
  for (const value of values) result += `- ${formatValue(value)}\n`
  return result
}

const formatValidationResults = (results) => {
  if (!results) return 'Validation results not available'

  let result = 'Collection Validation Results:\n'
  result += `- Collection: ${results.ns}\n`
  result += `- Valid: ${results.valid}\n`

  if (results.errors && results.errors.length > 0) {
    result += `- Errors: ${results.errors}\n`
  }

  if (results.warnings && results.warnings.length > 0) {
    result += `- Warnings: ${results.warnings}\n`
  }

  if (results.nrecords !== undefined) {
    result += `- Records Validated: ${results.nrecords}\n`
  }

  if (results.nInvalidDocuments !== undefined) {
    result += `- Invalid Documents: ${results.nInvalidDocuments}\n`
  }

  if (results.advice) {
    result += `- Advice: ${results.advice}\n`
  }

  return result
}

const formatInsertResult = (result) => {
  if (!result) return 'Insert operation result not available'

  let output = 'Document inserted successfully\n'
  output += `- ID: ${result.insertedId}\n`
  output += `- Acknowledged: ${result.acknowledged}\n`

  return output
}

// Format function for update results
const formatUpdateResult = (result) => {
  if (!result) return 'Update operation result not available'

  let output = 'Document update operation complete\n'
  output += `- Matched: ${result.matchedCount}\n`
  output += `- Modified: ${result.modifiedCount}\n`
  output += `- Acknowledged: ${result.acknowledged}\n`

  if (result.upsertedId) {
    output += `- Upserted ID: ${result.upsertedId}\n`
  }

  return output
}

const formatMapReduceResults = (results) => {
  if (!results || !Array.isArray(results)) return 'Map-Reduce results not available'
  let output = `Map-Reduce Results (${results.length} entries):\n`
  for (const result of results) {
    output += `- Key: ${formatValue(result._id)}\n`
    output += `  Value: ${formatValue(result.value)}\n`
  }
  return output
}

const formatBulkResult = (result) => {
  if (!result) return 'Bulk operation results not available'

  let output = 'Bulk Operations Results:\n'
  output += `- Acknowledged: ${result.acknowledged}\n`

  if (result.insertedCount) output += `- Inserted: ${result.insertedCount}\n`
  if (result.matchedCount) output += `- Matched: ${result.matchedCount}\n`
  if (result.modifiedCount) output += `- Modified: ${result.modifiedCount}\n`
  if (result.deletedCount) output += `- Deleted: ${result.deletedCount}\n`
  if (result.upsertedCount) output += `- Upserted: ${result.upsertedCount}\n`

  if (result.insertedIds && Object.keys(result.insertedIds).length > 0) {
    output += '- Inserted IDs:\n'
    for (const [index, id] of Object.entries(result.insertedIds)) {
      output += `  - Index ${index}: ${id}\n`
    }
  }

  if (result.upsertedIds && Object.keys(result.upsertedIds).length > 0) {
    output += '- Upserted IDs:\n'
    for (const [index, id] of Object.entries(result.upsertedIds)) {
      output += `  - Index ${index}: ${id}\n`
    }
  }

  return output
}

const formatSize = (sizeInBytes) => {
  if (sizeInBytes < 1024) return `${sizeInBytes} bytes`
  if (sizeInBytes < 1024 * 1024) return `${(sizeInBytes / 1024).toFixed(2)} KB`
  if (sizeInBytes < 1024 * 1024 * 1024) return `${(sizeInBytes / (1024 * 1024)).toFixed(2)} MB`
  return `${(sizeInBytes / (1024 * 1024 * 1024)).toFixed(2)} GB`
}

const formatUptime = (seconds) => {
  if (seconds === undefined) return 'Unknown'

  const days = Math.floor(seconds / 86400)
  const hours = Math.floor((seconds % 86400) / 3600)
  const minutes = Math.floor((seconds % 3600) / 60)
  const remainingSeconds = Math.floor(seconds % 60)

  const parts = []
  if (days > 0) parts.push(`${days}d`)
  if (hours > 0) parts.push(`${hours}h`)
  if (minutes > 0) parts.push(`${minutes}m`)
  if (remainingSeconds > 0 || parts.length === 0) parts.push(`${remainingSeconds}s`)

  return parts.join(' ')
}

const formatValue = (value) => {
  if (value === null) return 'null'
  if (value === undefined) return 'undefined'

  if (typeof value === 'object') {
    return JSON.stringify(value)
  }

  return String(value)
}

const formatChangeStreamResults = (changes, duration) => {
  if (changes.length === 0) {
    return `No changes detected during ${duration} second window.`
  }

  let result = `Detected ${changes.length} changes during ${duration} second window:\n\n`

  for (const change of changes) {
    result += `Operation: ${change.operationType}\n`
    result += `Timestamp: ${new Date(change.clusterTime.high * 1000).toISOString()}\n`

    if (change.documentKey) {
      result += `Document ID: ${JSON.stringify(change.documentKey)}\n`
    }

    if (change.fullDocument) {
      result += `Document: ${JSON.stringify(change.fullDocument, null, 2)}\n`
    }

    if (change.updateDescription) {
      result += `Updated Fields: ${JSON.stringify(change.updateDescription.updatedFields, null, 2)}\n`
      result += `Removed Fields: ${JSON.stringify(change.updateDescription.removedFields)}\n`
    }

    result += '\n'
  }

  return result
}

const formatTextSearchResults = (results, searchText) => {
  if (results.length === 0) {
    return `No documents found matching: "${searchText}"`
  }

  let output = `Found ${results.length} documents matching: "${searchText}"\n\n`

  for (const doc of results) {
    const score = doc.score
    delete doc.score
    output += `Score: ${score.toFixed(2)}\n`
    output += `Document: ${JSON.stringify(serializeDocument(doc), null, 2)}\n\n`
  }

  output += `Note: Make sure text indexes exist on relevant fields. Create with: create-index {"collection": "yourCollection", "keys": "{\\"fieldName\\": \\"text\\"}"}`

  return output
}

const formatTransactionResults = (results) => {
  let output = 'Transaction completed successfully:\n\n'

  for (const result of results) {
    output += `Step ${result.step}: ${result.operation}\n`

    if (result.operation === 'insert') {
      output += `- Inserted ID: ${result.result.insertedId}\n`
    } else if (result.operation === 'update') {
      output += `- Matched: ${result.result.matchedCount}\n`
      output += `- Modified: ${result.result.modifiedCount}\n`
    } else if (result.operation === 'delete') {
      output += `- Deleted: ${result.result.deletedCount}\n`
    } else if (result.operation === 'find') {
      output += `- Document: ${JSON.stringify(serializeDocument(result.result), null, 2)}\n`
    }

    output += '\n'
  }

  return output
}

const formatGridFSList = (files) => {
  if (files.length === 0) {
    return 'No files found in GridFS'
  }

  let result = `GridFS Files (${files.length}):\n\n`

  for (const file of files) {
    result += `Filename: ${file.filename}\n`
    result += `Size: ${formatSize(file.length)}\n`
    result += `Upload Date: ${file.uploadDate.toISOString()}\n`
    result += `ID: ${file._id}\n`
    if (file.metadata) result += `Metadata: ${JSON.stringify(file.metadata)}\n`
    result += '\n'
  }

  return result
}

const getFileId = async (bucket, filename) => {
  const file = await currentDb.collection(`${bucket}.files`).findOne({ filename })
  if (!file) throw new Error(`File '${filename}' not found`)
  return file._id
}

const formatGridFSInfo = (file) => {
  let result = 'GridFS File Information:\n\n'

  result += `Filename: ${file.filename}\n`
  result += `Size: ${formatSize(file.length)}\n`
  result += `Chunk Size: ${formatSize(file.chunkSize)}\n`
  result += `Upload Date: ${file.uploadDate.toISOString()}\n`
  result += `ID: ${file._id}\n`
  result += `MD5: ${file.md5}\n`

  if (file.contentType) result += `Content Type: ${file.contentType}\n`
  if (file.aliases && file.aliases.length > 0) result += `Aliases: ${file.aliases.join(', ')}\n`
  if (file.metadata) result += `Metadata: ${JSON.stringify(file.metadata, null, 2)}\n`

  return result
}

const formatCollationResults = (results, locale, strength, caseLevel) => {
  if (results.length === 0) {
    return 'No documents found matching the query with the specified collation'
  }

  let output = `Found ${results.length} documents using collation:\n`
  output += `- Locale: ${locale}\n`
  output += `- Strength: ${strength} (${getStrengthDescription(strength)})\n`
  output += `- Case Level: ${caseLevel}\n\n`

  output += results.map(doc => JSON.stringify(serializeDocument(doc), null, 2)).join('\n\n')
  return output
}

const getStrengthDescription = (strength) => {
  const descriptions = {
    1: 'Primary - base characters only',
    2: 'Secondary - base + accents',
    3: 'Tertiary - base + accents + case + variants',
    4: 'Quaternary - base + accents + case + variants + punctuation',
    5: 'Identical - exact matches only'
  }
  return descriptions[strength] || 'Custom'
}

const formatShardDbStatus = (shards, dbStats, dbShardStatus, dbName) => {
  let result = `Sharding Status for Database: ${dbName}\n\n`

  if (!shards || !shards.shards || shards.shards.length === 0) {
    return result + 'This MongoDB deployment is not a sharded cluster.'
  }

  result += `Cluster consists of ${shards.shards.length} shards:\n`
  for (const shard of shards.shards) {
    result += `- ${shard._id}: ${shard.host}\n`
  }
  result += '\n'

  if (dbShardStatus) {
    result += `Database Sharding Status: ${dbShardStatus.partitioned ? 'Enabled' : 'Not Enabled'}\n`
    if (dbShardStatus.primary) result += `Primary Shard: ${dbShardStatus.primary}\n\n`
  } else {
    result += 'Database is not sharded.\n\n'
  }

  if (dbStats && dbStats.raw) {
    result += 'Data Distribution:\n'
    for (const shard in dbStats.raw) {
      result += `- ${shard}: ${formatSize(dbStats.raw[shard].totalSize)} (${dbStats.raw[shard].objects} objects)\n`
    }
  }

  return result
}

const formatShardCollectionStatus = (stats, shardStatus, collName) => {
  let result = `Sharding Status for Collection: ${collName}\n\n`

  if (!stats.sharded) {
    return result + 'This collection is not sharded.'
  }

  result += 'Collection is sharded.\n\n'

  if (shardStatus) {
    result += `Shard Key: ${JSON.stringify(shardStatus.key)}\n`
    if (shardStatus.unique) result += 'Unique: true\n'
    result += `Distribution Mode: ${shardStatus.dropped ? 'Dropped' : shardStatus.distributionMode || 'hashed'}\n\n`
  }

  if (stats.shards) {
    result += 'Data Distribution:\n'
    for (const shard in stats.shards) {
      result += `- ${shard}: ${formatSize(stats.shards[shard].size)} (${stats.shards[shard].count} documents)\n`
    }
  }

  if (stats.chunks) {
    result += `\nTotal Chunks: ${stats.chunks}\n`
  }

  return result
}

const formatPerformanceMetrics = (metrics) => {
  let result = 'MongoDB Performance Metrics:\n\n'

  if (metrics.error) {
    return `Error retrieving metrics: ${metrics.error}`
  }

  result += '## Server Status\n'
  if (metrics.serverStatus.connections) {
    result += `- Current Connections: ${metrics.serverStatus.connections.current}\n`
    result += `- Available Connections: ${metrics.serverStatus.connections.available}\n`
  }

  if (metrics.serverStatus.opcounters) {
    result += '\n## Operation Counters (since server start)\n'
    for (const [op, count] of Object.entries(metrics.serverStatus.opcounters)) {
      result += `- ${op}: ${count}\n`
    }
  }

  if (metrics.serverStatus.wiredTiger) {
    result += '\n## Cache Utilization\n'
    result += `- Pages Read: ${metrics.serverStatus.wiredTiger.pages_read}\n`
    result += `- Max Bytes: ${formatSize(metrics.serverStatus.wiredTiger.maximum_bytes_configured)}\n`
    result += `- Current Bytes: ${formatSize(metrics.serverStatus.wiredTiger.bytes_currently_in_cache)}\n`
    result += `- Dirty Bytes: ${formatSize(metrics.serverStatus.wiredTiger.tracked_dirty_bytes)}\n`
  }

  result += '\n## Database Profiling\n'
  result += `- Profiling Level: ${metrics.profileSettings.was}\n`
  result += `- Slow Query Threshold: ${metrics.profileSettings.slowms}ms\n`

  if (metrics.currentOperations && metrics.currentOperations.length > 0) {
    result += '\n## Long-Running Operations\n'
    for (const op of metrics.currentOperations) {
      result += `- Op: ${op.op} running for ${op.secs_running}s\n`
      result += `  - Namespace: ${op.ns}\n`
      if (op.query) result += `  - Query: ${JSON.stringify(op.query)}\n`
      if (op.command) result += `  - Command: ${JSON.stringify(op.command)}\n`
      result += '\n'
    }
  }

  return result
}

const formatTriggerConfiguration = (triggers) => {
  if (triggers.error) {
    return `Trigger information not available: ${triggers.error}`
  }

  let result = 'MongoDB Event Trigger Configuration:\n\n'

  result += '## Change Stream Support\n'
  if (triggers.changeStreams.supported) {
    result += '- Change streams are supported in this MongoDB version\n'
    result += `- Resume token support: ${triggers.changeStreams.resumeTokenSupported ? 'Yes' : 'No'}\n`
    result += `- Update lookup support: ${triggers.changeStreams.updateLookupSupported ? 'Yes' : 'No'}\n`
    result += `- Full document before change: ${triggers.changeStreams.fullDocumentBeforeChangeSupported ? 'Yes' : 'No'}\n`
  } else {
    result += '- Change streams are not supported in this MongoDB deployment\n'
    if (triggers.changeStreams.reason) {
      result += `  Reason: ${triggers.changeStreams.reason}\n`
    }
    if (triggers.changeStreams.howToEnable) {
      result += `  How to Enable: ${triggers.changeStreams.howToEnable}\n`
    }
  }

  result += '\n## Potential Trigger Collections\n'
  if (triggers.triggerCollections && triggers.triggerCollections.length > 0) {
    for (const coll of triggers.triggerCollections) {
      result += `- ${coll.name} (${coll.type})\n`
    }
  } else {
    result += '- No collections found with trigger-related naming\n'
  }

  result += '\n## Stored Trigger Functions\n'
  if (triggers.triggerFunctions && triggers.triggerFunctions.length > 0) {
    for (const func of triggers.triggerFunctions) {
      result += `- ${func._id}\n`
      if (typeof func.value === 'function') {
        result += `  ${func.value.toString().split('\n')[0]}…\n`
      }
    }
  } else {
    result += '- No stored JavaScript functions with trigger-related naming found\n'
  }

  return result
}

const formatSchemaComparison = (comparison, sourceCollection, targetCollection) => {
  const { source, target, commonFields, sourceOnlyFields, targetOnlyFields, typeDifferences, stats } = comparison

  let result = `# Schema Comparison: '${source}' vs '${target}'\n\n`

  result += `## Summary\n`
  result += `- Source Collection: ${source} (${stats.sourceFieldCount} fields)\n`
  result += `- Target Collection: ${target} (${stats.targetFieldCount} fields)\n`
  result += `- Common Fields: ${stats.commonFieldCount}\n`
  result += `- Fields Only in Source: ${sourceOnlyFields.length}\n`
  result += `- Fields Only in Target: ${targetOnlyFields.length}\n`
  result += `- Type Mismatches: ${typeDifferences.length}\n\n`

  if (typeDifferences.length > 0) {
    result += `## Type Differences\n`
    typeDifferences.forEach(diff => {
      result += `- ${diff.field}: ${diff.sourceTypes.join(', ')} (${source}) vs ${diff.targetTypes.join(', ')} (${target})\n`
    })
    result += '\n'
  }

  if (sourceOnlyFields.length > 0) {
    result += `## Fields Only in ${source}\n`
    sourceOnlyFields.forEach(field => {
      result += `- ${field.name}: ${field.types.join(', ')}\n`
    })
    result += '\n'
  }

  if (targetOnlyFields.length > 0) {
    result += `## Fields Only in ${target}\n`
    targetOnlyFields.forEach(field => {
      result += `- ${field.name}: ${field.types.join(', ')}\n`
    })
    result += '\n'
  }

  if (stats.commonFieldCount > 0) {
    result += `## Common Fields\n`
    commonFields.forEach(field => {
      const statusSymbol = field.typesMatch ? '✓' : '✗'
      result += `- ${statusSymbol} ${field.name}\n`
    })
  }

  return result
}

const formatQueryAnalysis = (analysis) => {
  const { collection, indexRecommendations, queryOptimizations, unusedIndexes, schemaIssues, queryStats } = analysis

  let result = `# Query Pattern Analysis for '${collection}'\n\n`

  if (indexRecommendations.length > 0) {
    result += `## Index Recommendations\n`
    indexRecommendations.forEach((rec, i) => {
      result += `### ${i+1}. Create index on: ${rec.fields.join(', ')}\n`
      if (rec.filter && !rec.automatic) {
        result += `- Based on query filter: ${rec.filter}\n`
        if (rec.millis) {
          result += `- Current execution time: ${rec.millis}ms\n`
        }
      } else if (rec.automatic) {
        result += `- Automatic recommendation based on field name patterns\n`
      }
      result += `- Create using: \`create-index {"collection": "${collection}", "keys": "{\\"${rec.fields[0]}\\": 1}"}\`\n\n`
    })
  }

  if (unusedIndexes.length > 0) {
    result += `## Unused Indexes\n`
    result += 'The following indexes appear to be unused and could potentially be removed:\n'
    unusedIndexes.forEach((idx) => {
      result += `- ${idx.name} on fields: ${idx.fields.join(', ')}\n`
    })
    result += '\n'
  }

  if (schemaIssues.length > 0) {
    result += `## Schema Concerns\n`
    schemaIssues.forEach((issue) => {
      result += `- ${issue.field}: ${issue.issue} - ${issue.description}\n`
    })
    result += '\n'
  }

  if (queryStats.length > 0) {
    result += `## Recent Queries\n`
    result += 'Most recent query patterns observed:\n'

    const uniquePatterns = {}
    queryStats.forEach(stat => {
      const key = stat.filter
      if (!uniquePatterns[key]) {
        uniquePatterns[key] = {
          filter: stat.filter,
          fields: stat.fields,
          count: 1,
          totalTime: stat.millis,
          avgTime: stat.millis,
          scanType: stat.scanType
        }
      } else {
        uniquePatterns[key].count++
        uniquePatterns[key].totalTime += stat.millis
        uniquePatterns[key].avgTime = uniquePatterns[key].totalTime / uniquePatterns[key].count
      }
    })

    Object.values(uniquePatterns)
      .sort((a, b) => b.avgTime - a.avgTime)
      .slice(0, 5)
      .forEach(pattern => {
        result += `- Filter: ${pattern.filter}\n`
        result += `  - Fields: ${pattern.fields.join(', ')}\n`
        result += `  - Count: ${pattern.count}\n`
        result += `  - Avg Time: ${pattern.avgTime.toFixed(2)}ms\n`
        result += `  - Scan Type: ${pattern.scanType}\n\n`
      })
  }

  return result
}

const formatExport = async (documents, format = config.tools.export.defaultFormat, fields = null, limit = config.tools.export.defaultLimit) => {
  log(`DB Operation: Formatting ${documents.length} documents for export in ${format} format…`)
  try {
    const limitedDocs = limit !== -1
      ? documents.slice(0, limit)
      : documents

    if (format === 'json') {
      return JSON.stringify(limitedDocs, (key, value) => serializeForExport(value), 2)
    } else if (format === 'csv') {
      if (!fields || !fields.length) {
        if (limitedDocs.length > 0) {
          fields = Object.keys(limitedDocs[0])
        } else {
          return 'No documents found for export'
        }
      }

      let csv = fields.join(',') + '\n'

      for (const doc of limitedDocs) {
        const row = fields.map(field => {
          const value = getNestedValue(doc, field)
          return formatCsvValue(value)
        })
        csv += row.join(',') + '\n'
      }

      return csv
    }

    throw new Error(`Unsupported export format: ${format}`)
  } catch (error) {
    log(`DB Operation: Export formatting failed: ${error.message}`)
    throw error
  }
}

const serializeForExport = (value) => {
  if (value instanceof ObjectId) {
    return value.toString()
  } else if (value instanceof Date) {
    return value.toISOString()
  }
  return value
}

const formatCsvValue = (value) => {
  if (value === null || value === undefined) return ''

  const stringValue = typeof value === 'object' ? JSON.stringify(value) : String(value)

  if (stringValue.includes(',') || stringValue.includes('\n') || stringValue.includes('"')) {
    return `"${stringValue.replace(/"/g, '""')}"`
  }

  return stringValue
}

const serializeDocument = (doc) => {
  const result = {}

  for (const [key, value] of Object.entries(doc)) {
    if (value instanceof ObjectId) {
      result[key] = `ObjectId("${value.toString()}")`
    } else if (value instanceof Date) {
      result[key] = `ISODate("${value.toISOString()}")`
    } else if (typeof value === 'object' && value !== null) {
      result[key] = serializeDocument(value)
    } else {
      result[key] = value
    }
  }

  return result
}

const compareSchemas = (sourceSchema, targetSchema) => {
  const result = {
    source: sourceSchema.collectionName,
    target: targetSchema.collectionName,
    commonFields: [],
    sourceOnlyFields: [],
    targetOnlyFields: [],
    typeDifferences: []
  }

  const sourceFields = Object.keys(sourceSchema.fields)
  const targetFields = Object.keys(targetSchema.fields)

  sourceFields.forEach(field => {
    if (targetFields.includes(field)) {
      const sourceTypes = sourceSchema.fields[field].types
      const targetTypes = targetSchema.fields[field].types

      const typesMatch = arraysEqual(sourceTypes, targetTypes)

      result.commonFields.push({
        name: field,
        sourceTypes,
        targetTypes,
        typesMatch
      })

      if (!typesMatch) {
        result.typeDifferences.push({
          field,
          sourceTypes,
          targetTypes
        })
      }
    } else {
      result.sourceOnlyFields.push({
        name: field,
        types: sourceSchema.fields[field].types
      })
    }
  })

  targetFields.forEach(field => {
    if (!sourceFields.includes(field)) {
      result.targetOnlyFields.push({
        name: field,
        types: targetSchema.fields[field].types
      })
    }
  })

  result.stats = {
    sourceFieldCount: sourceFields.length,
    targetFieldCount: targetFields.length,
    commonFieldCount: result.commonFields.length,
    mismatchCount: result.typeDifferences.length
  }

  return result
}

const analyzeQueryPatterns = (collection, schema, indexes, queryStats) => {
  const analysis = {
    collection,
    indexRecommendations: [],
    queryOptimizations: [],
    unusedIndexes: [],
    schemaIssues: [],
    queryStats: []
  }

  const indexMap = {}
  indexes.forEach(idx => {
    indexMap[idx.name] = {
      key: idx.key,
      unique: !!idx.unique,
      sparse: !!idx.sparse,
      fields: Object.keys(idx.key),
      usage: idx.usage || { ops: 0, since: new Date() }
    }
  })

  for (const [name, idx] of Object.entries(indexMap)) {
    if (name !== '_id_' && (!idx.usage || idx.usage.ops === 0)) {
      analysis.unusedIndexes.push({
        name,
        fields: idx.fields,
        properties: idx.unique ? 'unique' : ''
      })
    }
  }

  if (queryStats && queryStats.length > 0) {
    queryStats.forEach(stat => {
      if (stat.command && stat.command.filter) {
        const filter = stat.command.filter
        const queryFields = Object.keys(filter)
        const millis = stat.millis || 0

        analysis.queryStats.push({
          filter: JSON.stringify(filter),
          fields: queryFields,
          millis,
          scanType: stat.planSummary || 'Unknown',
          timestamp: stat.ts
        })

        const hasMatchingIndex = indexes.some(idx => {
          const indexFields = Object.keys(idx.key)
          return queryFields.every(field => indexFields.includes(field))
        })

        if (!hasMatchingIndex && queryFields.length > 0 && millis > config.defaults.slowMs) {
          analysis.indexRecommendations.push({
            fields: queryFields,
            filter: JSON.stringify(filter),
            millis
          })
        }
      }
    })
  }

  const schemaFields = Object.entries(schema.fields)

  schemaFields.forEach(([fieldName, info]) => {
    if (info.types.includes('array') && info.sample && Array.isArray(info.sample) && info.sample.length > 50) {
      analysis.schemaIssues.push({
        field: fieldName,
        issue: 'Large array',
        description: `Field contains arrays with ${info.sample.length}+ items, which can cause performance issues.`
      })
    }
  })

  const likelyQueryFields = schemaFields
    .filter(([name, info]) => {
      const lowerName = name.toLowerCase()
      return (
        lowerName.includes('id') ||
        lowerName.includes('key') ||
        lowerName.includes('date') ||
        lowerName.includes('time') ||
        lowerName === 'email' ||
        lowerName === 'name' ||
        lowerName === 'status'
      ) && !indexMap._id_ && !indexMap[name + '_1']
    })
    .map(([name]) => name)

  if (likelyQueryFields.length > 0) {
    analysis.indexRecommendations.push({
      fields: likelyQueryFields,
      filter: 'Common query field pattern',
      automatic: true
    })
  }

  return analysis
}

const generateJsonSchemaValidator = (schema, strictness) => {
  const validator = {
    $jsonSchema: {
      bsonType: "object",
      required: [],
      properties: {}
    }
  }

  const requiredThreshold =
    strictness === 'strict' ? 90 :
    strictness === 'moderate' ? 75 :
    60

  Object.entries(schema.fields).forEach(([fieldPath, info]) => {
    if (fieldPath.includes('.')) return

    const cleanFieldPath = fieldPath.replace('[]', '')

    let bsonTypes = []
    info.types.forEach(type => {
      switch(type) {
        case 'string':
          bsonTypes.push('string')
          break
        case 'number':
          bsonTypes.push('number', 'double', 'int')
          break
        case 'boolean':
          bsonTypes.push('bool')
          break
        case 'array':
          bsonTypes.push('array')
          break
        case 'object':
          bsonTypes.push('object')
          break
        case 'null':
          bsonTypes.push('null')
          break
        case 'Date':
          bsonTypes.push('date')
          break
        case 'ObjectId':
          bsonTypes.push('objectId')
          break
      }
    })

    const fieldSchema = bsonTypes.length === 1
      ? { bsonType: bsonTypes[0] }
      : { bsonType: bsonTypes }

    validator.$jsonSchema.properties[cleanFieldPath] = fieldSchema

    const coverage = info.coverage || Math.round((info.count / schema.sampleSize) * 100)
    if (coverage >= requiredThreshold && !info.types.includes('null')) {
      validator.$jsonSchema.required.push(cleanFieldPath)
    }
  })

  if (strictness === 'strict') {
    validator.$jsonSchema.additionalProperties = false
  }

  return validator
}

const createStreamingResultStream = () => {
  return new Transform({
    objectMode: true,
    transform(chunk, encoding, callback) {
      callback(null, chunk)
    }
  })
}

const processAggregationPipeline = (pipeline) => {
  if (!pipeline || !Array.isArray(pipeline)) return pipeline

  return pipeline.map(stage => {
    for (const operator in stage) {
      const value = stage[operator]
      if (typeof value === 'object' && value !== null) {
        if (operator === '$match' && value.$text) {
          if (value.$text.$search && typeof value.$text.$search === 'string') {
            const sanitizedSearch = sanitizeTextSearch(value.$text.$search)
            const textQuery = { $search: sanitizedSearch }
            if (value.$text.$language) textQuery.$language = value.$text.$language
            if (value.$text.$caseSensitive !== undefined) textQuery.$caseSensitive = value.$text.$caseSensitive
            if (value.$text.$diacriticSensitive !== undefined) textQuery.$diacriticSensitive = value.$text.$diacriticSensitive
            value.$text = textQuery
          }
        }
      }
    }
    return stage
  })
}

const sanitizeTextSearch = (searchText) => {
  if (!searchText) return ''
  return searchText.replace(/\$/g, '').replace(/[\u0000-\u001F\u007F-\u009F]/g, '')
}

const monitorBinarySize = (size) => {
  const mb = size / (1024 * 1024)
  if (mb > 10) {
    log(`Warning: Large binary data detected (${mb.toFixed(2)} MB)`, true)
  }
  return mb < 50
}

const getNestedValue = (obj, path) => {
  const parts = path.split('.')
  let current = obj

  for (const part of parts) {
    if (current === null || current === undefined) {
      return undefined
    }
    current = current[part]
  }

  return current
}

const generateDropToken = () => {
  const maxToken = Math.pow(10, config.security.tokenLength)
  return String(Math.floor(Math.random() * maxToken)).padStart(config.security.tokenLength, '0')
}

const storeDropDatabaseToken = (dbName) => {
  const token = generateDropToken()
  confirmationTokens.dropDatabase.set(dbName, {
    token,
    expires: Date.now() + config.security.tokenExpirationMinutes * 60 * 1000
  })
  return token
}

const validateDropDatabaseToken = (dbName, token) => {
  const storedData = confirmationTokens.dropDatabase.get(dbName)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.dropDatabase.delete(dbName)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.dropDatabase.delete(dbName)
  return true
}

const storeDropCollectionToken = (collectionName) => {
  const token = generateDropToken()
  confirmationTokens.dropCollection.set(collectionName, {
    token,
    expires: Date.now() + 5 * 60 * 1000
  })
  return token
}

const validateDropCollectionToken = (collectionName, token) => {
  const storedData = confirmationTokens.dropCollection.get(collectionName)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.dropCollection.delete(collectionName)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.dropCollection.delete(collectionName)
  return true
}

const storeDeleteDocumentToken = (collectionName, filter) => {
  const key = `${collectionName}:${JSON.stringify(filter)}`
  const token = generateDropToken()
  confirmationTokens.deleteDocument.set(key, {
    token,
    expires: Date.now() + 5 * 60 * 1000
  })
  return token
}

const validateDeleteDocumentToken = (collectionName, filter, token) => {
  const key = `${collectionName}:${JSON.stringify(filter)}`
  const storedData = confirmationTokens.deleteDocument.get(key)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.deleteDocument.delete(key)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.deleteDocument.delete(key)
  return true
}

const storeBulkOperationsToken = (collectionName, operations) => {
  const key = `${collectionName}:${operations.length}`
  const token = generateDropToken()
  confirmationTokens.bulkOperations.set(key, {
    token,
    expires: Date.now() + 5 * 60 * 1000,
    operations
  })
  return token
}

const validateBulkOperationsToken = (collectionName, operations, token) => {
  const key = `${collectionName}:${operations.length}`
  const storedData = confirmationTokens.bulkOperations.get(key)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.bulkOperations.delete(key)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.bulkOperations.delete(key)
  return true
}

const storeRenameCollectionToken = (oldName, newName, dropTarget) => {
  const key = `${oldName}:${newName}:${dropTarget}`
  const token = generateDropToken()
  confirmationTokens.renameCollection.set(key, {
    token,
    expires: Date.now() + 5 * 60 * 1000
  })
  return token
}

const validateRenameCollectionToken = (oldName, newName, dropTarget, token) => {
  const key = `${oldName}:${newName}:${dropTarget}`
  const storedData = confirmationTokens.renameCollection.get(key)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.renameCollection.delete(key)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.renameCollection.delete(key)
  return true
}

const storeDropUserToken = (username) => {
  const token = generateDropToken()
  confirmationTokens.dropUser.set(username, {
    token,
    expires: Date.now() + 5 * 60 * 1000
  })
  return token
}

const validateDropUserToken = (username, token) => {
  const storedData = confirmationTokens.dropUser.get(username)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.dropUser.delete(username)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.dropUser.delete(username)
  return true
}

const storeDropIndexToken = (collectionName, indexName) => {
  const key = `${collectionName}:${indexName}`
  const token = generateDropToken()
  confirmationTokens.dropIndex.set(key, {
    token,
    expires: Date.now() + 5 * 60 * 1000
  })
  return token
}

const validateDropIndexToken = (collectionName, indexName, token) => {
  const key = `${collectionName}:${indexName}`
  const storedData = confirmationTokens.dropIndex.get(key)
  if (!storedData) return false
  if (Date.now() > storedData.expires) {
    confirmationTokens.dropIndex.delete(key)
    return false
  }
  if (storedData.token !== token) return false
  confirmationTokens.dropIndex.delete(key)
  return true
}

const loadConfig = () => {
  let config = { ...defaultConfig }

  const configPathEnv = process.env.CONFIG_PATH

  let configPath = null
  if (configPathEnv) {
    configPath = configPathEnv
  } else {
    const homeDir = process.env.HOME || process.env.USERPROFILE || __dirname

    const jsoncPath = join(homeDir, '.mongodb-lens.jsonc')
    const jsonPath = join(homeDir, '.mongodb-lens.json')

    if (existsSync(jsoncPath)) {
      configPath = jsoncPath
    } else if (existsSync(jsonPath)) {
      configPath = jsonPath
    }
  }

  if (configPath && existsSync(configPath)) {
    try {
      log(`Loading config file: ${configPath}`)
      const fileContent = readFileSync(configPath, 'utf8')
      const strippedContent = stripJsonComments(fileContent)
      const configFile = JSON.parse(strippedContent)
      config = mergeConfigs(config, configFile)
    } catch (error) {
      console.error(`Error loading config file: ${error.message}`)
    }
  }

  config = applyEnvOverrides(config)

  if (process.argv.length > 2) {
    const cliArg = process.argv[2]
    config._cliMongoUri = cliArg
  }

  setupMongoUriMap(config)

  if (config._cliMongoUri) {
    const resolvedUri = resolveMongoUri(config._cliMongoUri)
    config.mongoUri = resolvedUri
    delete config._cliMongoUri
  }

  return config
}

const setupMongoUriMap = (config) => {
  mongoUriMap.clear()

  if (typeof config.mongoUri === 'object' && config.mongoUri !== null) {
    Object.entries(config.mongoUri).forEach(([alias, uri]) => {
      mongoUriMap.set(alias.toLowerCase(), uri)
    })

    const firstEntry = Object.entries(config.mongoUri)[0]
    if (firstEntry) {
      config.mongoUri = firstEntry[1]
      mongoUriAlias = firstEntry[0]
      log(`Using default connection alias: ${mongoUriAlias}`)
    } else {
      config.mongoUri = 'mongodb://localhost:27017'
    }
  } else if (typeof config.mongoUri === 'string') {
    mongoUriMap.set('default', config.mongoUri)
  }
}

const mergeConfigs = (target, source) =>
    _.merge({}, target, source)

const applyEnvOverrides = (config) => {
  const result = { ...config }

  const mapping = createEnvMapping(config)

  Object.entries(mapping).forEach(([configPath, envKey]) => {
    if (process.env[envKey] === undefined) return
    const defaultValue = getValueAtPath(config, configPath)
    const value = parseEnvValue(process.env[envKey], defaultValue, configPath)
    setValueAtPath(result, configPath, value)
  })

  return result
}

const createEnvMapping = (obj, prefix = 'CONFIG', path = '') => {
  let mapping = {}

  Object.entries(obj).forEach(([key, value]) => {
    const currentPath = path ? `${path}.${key}` : key
    const envKey = `${prefix}_${key.replace(/([A-Z])/g, '_$1').toUpperCase()}`

    if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
      const nestedMapping = createEnvMapping(value, `${prefix}_${key.toUpperCase()}`, currentPath)
      mapping = { ...mapping, ...nestedMapping }
    } else {
      mapping[currentPath] = envKey
    }
  })

  return mapping
}

const parseEnvValue = (value, defaultValue, path) => {
  try {
    if (typeof defaultValue === 'number') {
      const parsed = Number(value)
      if (isNaN(parsed)) throw new Error(`Invalid number for config [${path}]: ${value}`)
      return parsed
    }

    if (typeof defaultValue === 'boolean') {
      if (value.toLowerCase() !== 'true' && value.toLowerCase() !== 'false') {
        throw new Error(`Invalid boolean for config [${path}]: ${value}`)
      }
      return value.toLowerCase() === 'true'
    }

    if (Array.isArray(defaultValue)) {
      try {
        const parsed = JSON.parse(value)
        if (!Array.isArray(parsed)) throw new Error(`Config [${path}] is not an array`)
        return parsed
      } catch (e) {
        return value.split(',').map(item => item.trim())
      }
    }

    if (path === 'logLevel') {
      const validLogLevels = ['info', 'verbose']
      if (!validLogLevels.includes(value)) {
        throw new Error(`Config [${path}] is invalid: ${value}`)
      }
    }

    return value
  } catch (error) {
    console.error(`Error parsing environment variable for config [${path}]: ${error.message}. Using default: ${defaultValue}`)
    return defaultValue
  }
}

const getValueAtPath = (obj, path) =>
    _.get(obj, path)

const setValueAtPath = (obj, path, value) => {
  _.set(obj, path, value)
  return obj
}

const getPackageVersion = () => {
  if (packageVersion) return packageVersion
  const __filename = fileURLToPath(import.meta.url)
  const __dirname = dirname(__filename)
  const packageJson = JSON.parse(readFileSync(join(__dirname, 'package.json'), 'utf8'))
  packageVersion = packageJson.version
  return packageVersion
}

const createBooleanSchema = (description, defaultValue = 'true') =>
  z.string()
    .transform(val => val?.toLowerCase())
    .pipe(z.enum(['true', 'false']))
    .default(defaultValue)
    .describe(description)

const arraysEqual = (a, b) => {
  if (a.length !== b.length) return false
  return _.isEqual(_.sortBy(a), _.sortBy(b))
}

const log = (message, forceLog = false) => {
  if (forceLog || process.env.CONFIG_LOG_LEVEL === 'verbose' || globalThis.config && config.logLevel === 'verbose') console.error(message)
}

const cleanup = async () => {
  if (watchdog) {
    clearInterval(watchdog)
    watchdog = null
  }

  if (server) {
    try {
      log('Closing MCP server…')
      await server.close()
      log('MCP server closed.')
    } catch (error) {
      log(`Error closing MCP server: ${error.message}`, true)
    }
  }

  if (transport) {
    try {
      log('Closing transport…')
      await transport.close()
      log('Transport closed.')
    } catch (error) {
      log(`Error closing transport: ${error.message}`, true)
    }
  }

  if (mongoClient) {
    try {
      log('Closing MongoDB client…')
      await mongoClient.close()
      log('MongoDB client closed.')
    } catch (error) {
      log(`Error closing MongoDB client: ${error.message}`, true)
    }
  }

  clearMemoryCache()
}

const setupSignalHandlers = () => {
  process.on('SIGTERM', async () => {
    isShuttingDown = true
    log('Received SIGTERM, shutting down…')
    await cleanup()
    exit()
  })

  process.on('SIGINT', async () => {
    isShuttingDown = true
    log('Received SIGINT, shutting down…')
    await cleanup()
    exit()
  })
}

const exit = (exitCode = 1) => {
  log('Exiting…', true)
  process.exit(exitCode)
}

let server = null
let watchdog = null
let transport = null
let currentDb = null
let mongoClient = null
let currentDbName = null
let mongoUriAlias = null
let packageVersion = null
let connectionRetries = 0
let isShuttingDown = false
let mongoUriCurrent = null
let mongoUriMap = new Map()
let mongoUriOriginal = null
let isChangingConnection = false

const memoryCache = {
  stats: new Map(),
  fields: new Map(),
  schemas: new Map(),
  indexes: new Map(),
  collections: new Map(),
  serverStatus: new Map(),
}

const clearMemoryCache = () =>
  Object.values(memoryCache).forEach(cache => cache.clear())

const confirmationTokens = {
  dropUser: new Map(),
  dropIndex: new Map(),
  dropDatabase: new Map(),
  bulkOperations: new Map(),
  deleteDocument: new Map(),
  dropCollection: new Map(),
  renameCollection: new Map(),
}

const JSONRPC_ERROR_CODES = {
  // Standard JSON-RPC error codes (keep for compatibility)
  PARSE_ERROR: -32700,
  INVALID_REQUEST: -32600,
  METHOD_NOT_FOUND: -32601,
  INVALID_PARAMS: -32602,
  INTERNAL_ERROR: -32603,
  SERVER_ERROR_START: -32000,

  // MongoDB-specific error codes (expanded)
  MONGODB_CONNECTION_ERROR: -32050,
  MONGODB_QUERY_ERROR: -32051,
  MONGODB_SCHEMA_ERROR: -32052,
  MONGODB_WRITE_ERROR: -32053,
  MONGODB_DUPLICATE_KEY: -32054,
  MONGODB_TIMEOUT_ERROR: -32055,

  // Resource-related error codes
  RESOURCE_NOT_FOUND: -32040,
  RESOURCE_ACCESS_DENIED: -32041,
  RESOURCE_ALREADY_EXISTS: -32042
}

const instructions = `
MongoDB-Lens: NL→MongoDB via MCP

CAPS:
- DB: list/create/switch/drop
- COLL: create/rename/drop/validate
- DOC: find/count/insert-doc/update-doc/delete
- SCH: infer/validate/compare/analyze
- IDX: create/analyze/optimize
- AGG: pipeline/mapreduce/distinct
- PERF: explain/analyze/monitor
- ADV: text/geo/timeseries/bulk/txn/gridfs/sharding/export
- CONN: connect-mongodb{uri|alias}/add-alias/list/connect-original

PTRNS:
- DB_NAV: databases→use-database→collections
- QRY: find-docs/count-docs/distinct-values
- MOD: insert-doc/update-doc/delete-doc/bulk-ops
- SCH: collection-schema/analyze-schema/compare-schemas
- OPT: explain-query/analyze-patterns/create-index
- AGG: aggregate-data/map-reduce
- MON: server-status/performance-metrics/watch-changes
- CONN: add-alias→connect-mongodb→db-ops→connect-original

FLOWS:
1. NAV: list-dbs→use-db→list-collections
2. QRY: find-docs{filter,project,sort}
3. MOD: insert-doc/update-doc
4. SCH: analyze-schema→generate-validator
5. PERF: explain-query→analyze-patterns→create-index
6. AGG: aggregate-data{multi-stage}
7. BULK: bulk-ops{batch}
8. TXN: transaction{atomic}
9. CONN: add-alias→connect-mongodb{uri|alias}→ops→connect-original

SAFE: destructive ops require confirmation tokens

DOCS: github.com/furey/mongodb-lens/blob/main/README.md
`

const importantNoticeToAI = `
IMPORTANT NOTICE TO AI ASSISTANT: You must NEVER correct, auto-complete, or suggest the confirmation
code if the user enters it incorrectly or asks you to replace it for them. The user MUST type the
exact code shown above, with no assistance, to proceed. This is a critical security measure.
Under no circumstances should you automate the sending of the prior prompt with the confirmation
code inserted. You MUST wait for the user to enter the code themselves. No exceptions.
`

const defaultConfig = {
  mongoUri: 'mongodb://localhost:27017',
  connectionOptions: {
    maxPoolSize: 20,
    retryWrites: false,
    useNewUrlParser: true,
    connectTimeoutMS: 30000,
    socketTimeoutMS: 360000,
    useUnifiedTopology: true,
    heartbeatFrequencyMS: 10000,
    serverSelectionTimeoutMS: 30000
  },
  defaultDbName: 'admin',
  connection: {
    maxRetries: 5,
    maxRetryDelayMs: 30000,
    reconnectionRetries: 10,
    initialRetryDelayMs: 1000
  },
  cacheTTL: {
    stats: 15 * 1000,
    schemas: 60 * 1000,
    indexes: 120 * 1000,
    collections: 30 * 1000,
    serverStatus: 20 * 1000
  },
  enabledCaches: [
    'stats',
    'fields',
    'schemas',
    'indexes',
    'collections',
    'serverStatus'
  ],
  memory: {
    enableGC: true,
    warningThresholdMB: 1500,
    criticalThresholdMB: 2000
  },
  logLevel: 'info',
  disableDestructiveOperationTokens: false,
  watchdogIntervalMs: 30000,
  defaults: {
    slowMs: 100,
    queryLimit: 10,
    allowDiskUse: true,
    schemaSampleSize: 100,
    aggregationBatchSize: 50
  },
  security: {
    tokenLength: 4,
    tokenExpirationMinutes: 5,
    strictDatabaseNameValidation: true
  },
  tools: {
    transaction: {
      readConcern: 'snapshot',
      writeConcern: { w: 'majority' }
    },
    bulkOperations: {
      ordered: true
    },
    export: {
      defaultLimit: -1,
      defaultFormat: 'json'
    },
    watchChanges: {
      maxDurationSeconds: 60,
      defaultDurationSeconds: 10
    },
    queryAnalysis: {
      defaultDurationSeconds: 10
    }
  },
  disabled: {
    tools: [],
    prompts: [],
    resources: []
  }
}

setupSignalHandlers()

const config = loadConfig()

start(config.mongoUri)