import fs from 'fs/promises';
import path from 'path';
import { fileURLToPath } from 'url';
import { Config } from './types.js';
// Get __dirname for ES modules
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
// Get project root directory relative to src/config
const getProjectRoot = () => {
// Go up two levels from src/config to get to project root
return path.resolve(__dirname, '..', '..');
};
// Cache to avoid reading file multiple times
let cachedConfig: Config | null = null;
/**
* Get default configuration values
* These serve as fallbacks when config.json is missing or incomplete
*/
function getDefaultConfig(): Config {
return {
// This MUST be customized per machine
docsBasePath: process.env.DOCS_BASE_PATH || '/Users/shayon/DevProjects/~meta/docs',
crawler: {
defaultMaxDepth: 3,
defaultRateLimit: 2,
pageTimeout: 30000,
userAgent: 'Mozilla/5.0 (compatible; MCP-for-docs/1.0; +https://github.com/shayonpal/mcp-for-docs)'
},
cheatsheet: {
maxLength: 10000,
filenameSuffix: '-Cheatsheet.md'
}
};
}
/**
* Strip comments from JSON string
* Allows // style comments in config files for better documentation
*/
function stripJsonComments(jsonString: string): string {
// Remove single-line comments
let cleaned = jsonString.replace(/\/\/.*$/gm, '');
// Remove multi-line comments
cleaned = cleaned.replace(/\/\*[\s\S]*?\*\//g, '');
// Remove trailing commas (not valid in strict JSON)
cleaned = cleaned.replace(/,(\s*[}\]])/g, '$1');
return cleaned;
}
/**
* Validate configuration values
* Throws descriptive errors for invalid configurations
*/
function validateConfig(config: any): Config {
// Validate docsBasePath
if (!config.docsBasePath || typeof config.docsBasePath !== 'string') {
throw new Error('Configuration error: docsBasePath must be a non-empty string');
}
// Validate crawler settings
if (!config.crawler || typeof config.crawler !== 'object') {
throw new Error('Configuration error: crawler section is required');
}
if (!Number.isInteger(config.crawler.defaultMaxDepth) || config.crawler.defaultMaxDepth < 1) {
throw new Error('Configuration error: crawler.defaultMaxDepth must be a positive integer (recommended: 3)');
}
if (config.crawler.defaultMaxDepth > 10) {
console.warn('Warning: crawler.defaultMaxDepth > 10 may result in very long crawl times');
}
if (!Number.isInteger(config.crawler.defaultRateLimit) || config.crawler.defaultRateLimit < 1) {
throw new Error('Configuration error: crawler.defaultRateLimit must be a positive integer (recommended: 2)');
}
if (config.crawler.defaultRateLimit > 10) {
console.warn('Warning: crawler.defaultRateLimit > 10 may overwhelm some servers');
}
if (!Number.isInteger(config.crawler.pageTimeout) || config.crawler.pageTimeout < 1000) {
throw new Error('Configuration error: crawler.pageTimeout must be at least 1000ms');
}
if (!config.crawler.userAgent || typeof config.crawler.userAgent !== 'string') {
throw new Error('Configuration error: crawler.userAgent must be a non-empty string');
}
// Validate cheatsheet settings
if (!config.cheatsheet || typeof config.cheatsheet !== 'object') {
throw new Error('Configuration error: cheatsheet section is required');
}
if (!Number.isInteger(config.cheatsheet.maxLength) || config.cheatsheet.maxLength < 1000) {
throw new Error('Configuration error: cheatsheet.maxLength must be at least 1000');
}
if (!config.cheatsheet.filenameSuffix || typeof config.cheatsheet.filenameSuffix !== 'string') {
throw new Error('Configuration error: cheatsheet.filenameSuffix must be a non-empty string');
}
return config as Config;
}
/**
* Load configuration from file system
*/
export async function loadConfig(): Promise<Config> {
// Return cached config if available
if (cachedConfig) {
return cachedConfig;
}
const configPath = path.join(getProjectRoot(), 'config.json');
try {
const configData = await fs.readFile(configPath, 'utf-8');
let loadedConfig;
try {
// Try parsing directly first (since we have clean JSON)
loadedConfig = JSON.parse(configData);
} catch (parseError) {
// If direct parsing fails, try with comment stripping
const cleanedJson = stripJsonComments(configData);
loadedConfig = JSON.parse(cleanedJson);
}
// Get base config
const defaults = getDefaultConfig();
// Deep merge with defaults to fill in any missing values
// Environment variable takes precedence during testing
const mergedConfig = {
docsBasePath: process.env.DOCS_BASE_PATH || loadedConfig.docsBasePath || defaults.docsBasePath,
crawler: {
...defaults.crawler,
...loadedConfig.crawler
},
cheatsheet: {
...defaults.cheatsheet,
...loadedConfig.cheatsheet
}
};
// Validate and cache
cachedConfig = validateConfig(mergedConfig);
console.log(`Loaded configuration from: ${configPath}`);
return cachedConfig;
} catch (error) {
if ((error as any).code === 'ENOENT') {
throw new Error(
'Configuration file not found. Please create config.json in the project root.\n' +
'You can copy config.example.json as a starting point.'
);
}
throw error;
}
}
/**
* Clear cached configuration
* Useful for testing or when config file is updated
*/
export function clearConfigCache(): void {
cachedConfig = null;
}
