FreshBooks MCP Server

/** * Logging utility for FreshBooks MCP Server * * IMPORTANT: All logs go to stderr (stdout is reserved for MCP protocol) */ import type { LogLevel } from '../types/index.js'; const LOG_LEVELS: Record<LogLevel, number> = { debug: 0, info: 1, warn: 2, error: 3, }; class Logger { private currentLevel: LogLevel; private requestId: string | null = null; constructor(level: LogLevel = 'info') { this.currentLevel = level; } /** * Set the current log level */ setLevel(level: LogLevel): void { this.currentLevel = level; } /** * Set request ID for correlation */ setRequestId(id: string): void { this.requestId = id; } /** * Clear request ID */ clearRequestId(): void { this.requestId = null; } /** * Check if a log level should be output */ private shouldLog(level: LogLevel): boolean { return LOG_LEVELS[level] >= LOG_LEVELS[this.currentLevel]; } /** * Sanitize data to prevent logging sensitive information */ private sanitize(data: unknown): unknown { if (typeof data !== 'object' || data === null) { return data; } if (Array.isArray(data)) { return data.map((item) => this.sanitize(item)); } const sanitized: Record<string, unknown> = {}; const sensitiveKeys = [ 'token', 'accessToken', 'refreshToken', 'access_token', 'refresh_token', 'secret', 'password', 'clientSecret', 'client_secret', 'authorization', 'apiKey', 'api_key', ]; for (const [key, value] of Object.entries(data)) { const lowerKey = key.toLowerCase(); if (sensitiveKeys.some((sensitive) => lowerKey.includes(sensitive))) { sanitized[key] = '[REDACTED]'; } else { sanitized[key] = this.sanitize(value); } } return sanitized; } /** * Write structured log to stderr */ private write(level: LogLevel, message: string, context?: Record<string, unknown>): void { if (!this.shouldLog(level)) { return; } const logEntry = { timestamp: new Date().toISOString(), level, message, ...(this.requestId && { requestId: this.requestId }), ...(context && { context: this.sanitize(context) }), }; // Write to stderr only (stdout reserved for MCP protocol) process.stderr.write(JSON.stringify(logEntry) + '\n'); } /** * Log debug message */ debug(message: string, context?: Record<string, unknown>): void { this.write('debug', message, context); } /** * Log info message */ info(message: string, context?: Record<string, unknown>): void { this.write('info', message, context); } /** * Log warning message */ warn(message: string, context?: Record<string, unknown>): void { this.write('warn', message, context); } /** * Log error message */ error(message: string, error?: Error | unknown, context?: Record<string, unknown>): void { const errorContext: Record<string, unknown> = context ? { ...context } : {}; if (error instanceof Error) { errorContext.error = { name: error.name, message: error.message, stack: error.stack, }; } else if (error) { errorContext.error = this.sanitize(error); } this.write('error', message, errorContext); } } // Export singleton instance export const logger = new Logger();