import pc from 'picocolors';
export type LogLevel = 'INFO' | 'DEBUG' | 'SUCCESS' | 'WARNING' | 'ERROR';
export type LogMeta = Record<string, unknown>;
export interface LogEntry {
ts: string;
level: LogLevel;
scope: string;
message: string;
durationMs?: number;
meta?: LogMeta;
}
type LogTransmitter = (entry: LogEntry) => void | Promise<void>;
const transmitters = new Set<LogTransmitter>();
export function registerLogTransmitter(transmitter: LogTransmitter): () => void {
transmitters.add(transmitter);
return () => transmitters.delete(transmitter);
}
const levelColor: Record<LogLevel, (input: string) => string> = {
INFO: pc.cyan,
DEBUG: pc.gray,
SUCCESS: pc.green,
WARNING: pc.yellow,
ERROR: pc.red
};
transmitters.add((entry) => {
const color = levelColor[entry.level];
const prefix = `${entry.ts} ${entry.level.padEnd(7)} ${entry.scope}`;
const meta = entry.meta && Object.keys(entry.meta).length ? ` ${JSON.stringify(entry.meta)}` : '';
const duration = typeof entry.durationMs === 'number' ? ` (${entry.durationMs.toFixed(1)}ms)` : '';
console.error(color(`${prefix}: ${entry.message}${duration}${meta}`));
});
async function emit(entry: LogEntry) {
await Promise.allSettled(Array.from(transmitters).map(async (tx) => tx(entry)));
}
export class Logger {
constructor(private readonly scope: string) {}
child(suffix: string): Logger {
return new Logger(`${this.scope}.${suffix}`);
}
async log(level: LogLevel, message: string, meta?: LogMeta, durationMs?: number) {
const entry: LogEntry = {
ts: new Date().toISOString(),
level,
scope: this.scope,
message,
durationMs,
...(meta ? { meta } : {})
};
await emit(entry);
}
info(message: string, meta?: LogMeta) {
return this.log('INFO', message, meta);
}
debug(message: string, meta?: LogMeta) {
return this.log('DEBUG', message, meta);
}
success(message: string, meta?: LogMeta, durationMs?: number) {
return this.log('SUCCESS', message, meta, durationMs);
}
warn(message: string, meta?: LogMeta) {
return this.log('WARNING', message, meta);
}
error(message: string, meta?: LogMeta) {
return this.log('ERROR', message, meta);
}
}
export function createLogger(scope: string): Logger {
return new Logger(scope);
}
export function createStopwatch(): () => number {
const start = process.hrtime.bigint();
return () => Number(process.hrtime.bigint() - start) / 1_000_000;
}
