type LogLevel = 'debug' | 'info' | 'warn' | 'error';

const LEVELS: Record<LogLevel, number> = { debug: 0, info: 1, warn: 2, error: 3 };
const MIN_LEVEL = LEVELS[(process.env.LOG_LEVEL as LogLevel) || 'info'];

function ts(): string {
  return new Date().toISOString();
}

function format(level: LogLevel, context: string, message: string, data?: unknown): string {
  const base = `${ts()} [${level.toUpperCase()}] [${context}] ${message}`;
  if (data !== undefined) {
    const serialized =
      data instanceof Error ? `${data.message}\n${data.stack}` : JSON.stringify(data);
    return `${base} ${serialized}`;
  }
  return base;
}

function createLogger(context: string) {
  return {
    debug: (msg: string, data?: unknown) => {
      if (MIN_LEVEL <= LEVELS.debug) console.debug(format('debug', context, msg, data));
    },
    info: (msg: string, data?: unknown) => {
      if (MIN_LEVEL <= LEVELS.info) console.info(format('info', context, msg, data));
    },
    warn: (msg: string, data?: unknown) => {
      if (MIN_LEVEL <= LEVELS.warn) console.warn(format('warn', context, msg, data));
    },
    error: (msg: string, data?: unknown) => {
      if (MIN_LEVEL <= LEVELS.error) console.error(format('error', context, msg, data));
    },
  };
}

export { createLogger };