/**
* Logger utility for W3C MCP Server
* Provides debug logging controlled by environment variable
*/
const DEBUG = process.env.W3C_MCP_DEBUG === 'true';
const LOG_PERFORMANCE = process.env.W3C_MCP_PERF === 'true' || DEBUG;
/**
* Log debug message (only when W3C_MCP_DEBUG=true)
*/
export function debug(message: string, data?: unknown): void {
if (DEBUG) {
const timestamp = new Date().toISOString();
if (data !== undefined) {
console.error(`[${timestamp}] [DEBUG] ${message}`, JSON.stringify(data, null, 2));
} else {
console.error(`[${timestamp}] [DEBUG] ${message}`);
}
}
}
/**
* Log info message (always shown)
*/
export function info(message: string): void {
console.error(`[INFO] ${message}`);
}
/**
* Log warning message (always shown)
*/
export function warn(message: string, error?: Error): void {
if (error) {
console.error(`[WARN] ${message}:`, error.message);
} else {
console.error(`[WARN] ${message}`);
}
}
/**
* Log error message (always shown)
*/
export function error(message: string, err?: Error): void {
if (err) {
console.error(`[ERROR] ${message}:`, err.message);
if (DEBUG && err.stack) {
console.error(err.stack);
}
} else {
console.error(`[ERROR] ${message}`);
}
}
/**
* Performance measurement utilities
*/
export class PerformanceTimer {
private startTime: number;
private label: string;
constructor(label: string) {
this.label = label;
this.startTime = Date.now();
if (LOG_PERFORMANCE) {
debug(`${label} started`);
}
}
/**
* End the timer and log the duration
*/
end(): number {
const duration = Date.now() - this.startTime;
if (LOG_PERFORMANCE) {
console.error(`[PERF] ${this.label}: ${duration}ms`);
}
return duration;
}
/**
* Log an intermediate checkpoint
*/
checkpoint(name: string): number {
const duration = Date.now() - this.startTime;
if (LOG_PERFORMANCE) {
console.error(`[PERF] ${this.label} → ${name}: ${duration}ms`);
}
return duration;
}
}
/**
* Decorator-style performance logging
*/
export function logPerformance<T>(label: string, fn: () => T | Promise<T>): T | Promise<T> {
if (!LOG_PERFORMANCE) {
return fn();
}
const timer = new PerformanceTimer(label);
const result = fn();
if (result instanceof Promise) {
return result.finally(() => timer.end());
}
timer.end();
return result;
}
/**
* Log tool invocation (for debugging)
*/
export function logToolCall(toolName: string, args: unknown): void {
debug(`Tool called: ${toolName}`, args);
}
/**
* Log tool result (for debugging)
*/
export function logToolResult(toolName: string, resultSize: number): void {
debug(`Tool result: ${toolName}`, { resultSize });
}
