base-handler.ts•7.59 kB
import { Logger } from '../../utils/logger.js';
import { SFCCConfig } from '../../types/types.js';
export interface HandlerContext {
logger: Logger;
config: SFCCConfig;
capabilities: {
canAccessLogs: boolean;
canAccessOCAPI: boolean;
};
}
export interface ToolExecutionResult {
content: Array<{ type: 'text'; text: string }>;
isError?: boolean;
}
export interface ToolArguments {
[key: string]: any;
}
/**
* Generic tool specification interface
* Defines the contract for declarative tool configuration
*/
export interface GenericToolSpec<TArgs = ToolArguments, TResult = any> {
/** Optional validation function for tool arguments */
validate?: (args: TArgs, toolName: string) => void;
/** Optional function to apply default values to arguments */
defaults?: (args: TArgs) => Partial<TArgs>;
/** Main execution function for the tool */
exec: (args: TArgs, context: ToolExecutionContext) => Promise<TResult>;
/** Function to generate log message for the tool execution */
logMessage: (args: TArgs) => string;
}
/**
* Context provided to tool execution functions
* Allows tools to access clients and other resources
*/
export interface ToolExecutionContext {
/** Handler context with configuration and capabilities */
handlerContext: HandlerContext;
/** Logger instance for the handler */
logger: any;
/** Additional context data that can be provided by concrete handlers */
[key: string]: any;
}
export class HandlerError extends Error {
constructor(
message: string,
public readonly toolName: string,
public readonly code: string = 'HANDLER_ERROR',
public readonly details?: any,
) {
super(message);
this.name = 'HandlerError';
}
}
export abstract class BaseToolHandler<TToolName extends string = string> {
protected context: HandlerContext;
protected logger: Logger;
private _isInitialized = false;
constructor(context: HandlerContext, subLoggerName: string) {
this.context = context;
this.logger = Logger.getChildLogger(`Handler:${subLoggerName}`);
}
/**
* Abstract method to get tool configuration
* Each concrete handler implements this with their specific config
*/
protected abstract getToolConfig(): Record<TToolName, GenericToolSpec>;
/**
* Abstract method to get tool name set for O(1) lookup
* Each concrete handler implements this with their specific tool set
*/
protected abstract getToolNameSet(): Set<string>;
/**
* Abstract method to create execution context
* Each concrete handler can provide specialized context
*/
protected abstract createExecutionContext(): Promise<ToolExecutionContext>;
/**
* Check if this handler can handle the given tool
*/
canHandle(toolName: string): boolean {
return this.getToolNameSet().has(toolName);
}
/**
* Config-driven tool execution
* Handles validation, defaults, execution, and logging uniformly
*/
async handle(toolName: string, args: ToolArguments, startTime: number): Promise<ToolExecutionResult> {
if (!this.canHandle(toolName)) {
throw new Error(`Unsupported tool: ${toolName}`);
}
const toolConfig = this.getToolConfig();
const spec = toolConfig[toolName as TToolName];
if (!spec) {
throw new Error(`No configuration found for tool: ${toolName}`);
}
return this.executeWithLogging(
toolName,
startTime,
() => this.dispatchTool(spec, args),
spec.logMessage(this.applyDefaults(spec, args)),
);
}
/**
* Generic tool dispatch using configuration
* Handles validation, defaults, and execution
*/
private async dispatchTool(spec: GenericToolSpec, args: ToolArguments): Promise<any> {
const context = await this.createExecutionContext();
const processedArgs = this.createValidatedArgs(spec, args, 'tool');
return spec.exec(processedArgs, context);
}
/**
* Apply default values to arguments
*/
private applyDefaults(spec: GenericToolSpec, args: ToolArguments): ToolArguments {
if (!spec.defaults) {
return args;
}
const defaults = spec.defaults(args);
return { ...args, ...defaults };
}
/**
* Create validated arguments with defaults applied
*/
private createValidatedArgs(spec: GenericToolSpec, args: ToolArguments, toolName: string): ToolArguments {
// Apply defaults first
const processedArgs = this.applyDefaults(spec, args);
// Validate if validator exists
if (spec.validate) {
spec.validate(processedArgs, toolName);
}
return processedArgs;
}
/**
* Initialize the handler (lazy initialization)
*/
protected async initialize(): Promise<void> {
if (this._isInitialized) {
return;
}
await this.onInitialize();
this._isInitialized = true;
}
/**
* Override this method for custom initialization logic
*/
protected async onInitialize(): Promise<void> {
// Default: no-op
}
/**
* Clean up resources when handler is destroyed
*/
async dispose(): Promise<void> {
await this.onDispose();
this._isInitialized = false;
}
/**
* Override this method for custom cleanup logic
*/
protected async onDispose(): Promise<void> {
// Default: no-op
}
/**
* Validate required arguments
*/
protected validateArgs(args: ToolArguments, required: string[], toolName: string): void {
for (const field of required) {
if (!args?.[field]) {
throw new HandlerError(
`${field} is required`,
toolName,
'MISSING_ARGUMENT',
{ required, provided: Object.keys(args || {}) },
);
}
}
}
/**
* Create a standardized response
*/
protected createResponse(data: any, stringify: boolean = true): ToolExecutionResult {
return {
content: [
{ type: 'text', text: stringify ? JSON.stringify(data, null, 2) : data },
],
isError: false,
};
}
/**
* Create an error response
*/
protected createErrorResponse(error: Error, toolName: string): ToolExecutionResult {
this.logger.error(`Error in ${toolName}:`, error);
return {
content: [
{
type: 'text',
text: error instanceof HandlerError
? `Error: ${error.message}`
: `Error: ${error.message}`,
},
],
isError: true,
};
}
/**
* Execute a tool operation with standardized logging and error handling
*/
protected async executeWithLogging(
toolName: string,
startTime: number,
operation: () => Promise<any>,
logMessage?: string,
): Promise<ToolExecutionResult> {
try {
await this.initialize();
if (logMessage) {
this.logger.debug(logMessage);
}
const result = await operation();
this.logger.timing(toolName, startTime);
// Log result metadata for debugging
this.logger.debug(`${toolName} completed successfully`, {
resultType: typeof result,
resultLength: Array.isArray(result) ? result.length : undefined,
hasData: result != null,
});
return this.createResponse(result);
} catch (error) {
this.logger.timing(`${toolName}_error`, startTime);
return this.createErrorResponse(error as Error, toolName);
}
}
/**
* @deprecated Use executeWithLogging instead
*/
protected async wrap(
toolName: string,
startTime: number,
fn: () => Promise<any>,
logMessage?: string,
): Promise<ToolExecutionResult> {
return this.executeWithLogging(toolName, startTime, fn, logMessage);
}
}