type LogLevel = 'debug' | 'info' | 'warn' | 'error';
const LOG_LEVELS: Record<LogLevel, number> = {
debug: 0,
info: 1,
warn: 2,
error: 3,
};
let currentLevel: LogLevel = 'info';
/**
* Set the minimum log level. Messages below this level will be ignored.
*/
export function setLogLevel(level: LogLevel): void {
currentLevel = level;
}
/**
* Get the current log level.
*/
export function getLogLevel(): LogLevel {
return currentLevel;
}
function shouldLog(level: LogLevel): boolean {
return LOG_LEVELS[level] >= LOG_LEVELS[currentLevel];
}
function formatMessage(level: LogLevel, message: string, meta?: object): string {
const timestamp = new Date().toISOString();
const metaStr = meta ? ` ${JSON.stringify(meta)}` : '';
return `[${timestamp}] [${level.toUpperCase()}] ${message}${metaStr}`;
}
/**
* Log to stderr (MCP uses stdout for protocol messages).
*/
function log(level: LogLevel, message: string, meta?: object): void {
if (!shouldLog(level)) return;
console.error(formatMessage(level, message, meta));
}
export const logger = {
debug: (message: string, meta?: object) => log('debug', message, meta),
info: (message: string, meta?: object) => log('info', message, meta),
warn: (message: string, meta?: object) => log('warn', message, meta),
error: (message: string, meta?: object) => log('error', message, meta),
/** Log with timing information */
timed: <T>(label: string, fn: () => T): T => {
const start = performance.now();
try {
const result = fn();
const duration = performance.now() - start;
log('debug', `${label} completed`, { durationMs: duration.toFixed(2) });
return result;
} catch (err) {
const duration = performance.now() - start;
log('error', `${label} failed`, { durationMs: duration.toFixed(2) });
throw err;
}
},
/** Log with async timing information */
timedAsync: async <T>(label: string, fn: () => Promise<T>): Promise<T> => {
const start = performance.now();
try {
const result = await fn();
const duration = performance.now() - start;
log('debug', `${label} completed`, { durationMs: duration.toFixed(2) });
return result;
} catch (err) {
const duration = performance.now() - start;
log('error', `${label} failed`, { durationMs: duration.toFixed(2) });
throw err;
}
},
};
