import pino from 'pino';
import type { Logger } from 'pino';

export type { Logger };

/**
 * Builds the root pino logger. Called once at startup with the config values.
 *
 * In development, pino-pretty is used for human-readable output (lazy import
 * so it is never bundled in production paths). In test/production, raw JSON is
 * emitted — fast and parseable by log aggregators.
 */
export function createLogger(options: {
  level: string;
  nodeEnv: string;
  instanceId: string;
}): Logger {
  const { level, nodeEnv, instanceId } = options;

  const base = {
    service: 'tcp-ingestion',
    instance_id: instanceId,
  };

  // Emit `"level":"info"` instead of pino's default `"level":30` so log
  // viewers (Portainer, etc.) show a human-readable label rather than the
  // numeric level.
  const formatters = {
    level: (label: string) => ({ level: label }),
  };

  if (nodeEnv === 'development') {
    return pino({
      level,
      base,
      timestamp: pino.stdTimeFunctions.isoTime,
      formatters,
      transport: {
        target: 'pino-pretty',
        options: {
          colorize: true,
          translateTime: 'SYS:standard',
          ignore: 'pid,hostname',
        },
      },
    });
  }

  // Production and test: plain JSON — fast, no extra deps.
  // ISO-8601 string timestamps (vs default epoch-ms) survive downstream
  // log renderers (Portainer, Docker --timestamps) without losing seconds.
  return pino({ level, base, timestamp: pino.stdTimeFunctions.isoTime, formatters });
}