/**
 * Structured logging for email worker with daily rotation
 *
 * Uses pino for high-performance JSON logging.
 * Console output is human-readable via pino-pretty in dev,
 * and JSON in production (for Docker json-file driver).
 *
 * File logging uses a simple daily rotation approach.
 */

import pino from 'pino';
import { existsSync, mkdirSync, createWriteStream, type WriteStream } from 'node:fs';
import { join } from 'node:path';

// ---------------------------------------------------------------------------
// Configuration
// ---------------------------------------------------------------------------
const LOG_DIR = '/var/log/email-worker';
const LOG_FILE_PREFIX = 'worker';

// ---------------------------------------------------------------------------
// File stream (best-effort, never crashes the worker)
// ---------------------------------------------------------------------------
let fileStream: WriteStream | null = null;
let currentDateStr = '';

function getDateStr(): string {
  return new Date().toISOString().slice(0, 10); // YYYY-MM-DD
}

function ensureFileStream(): WriteStream | null {
  const today = getDateStr();
  if (fileStream && currentDateStr === today) return fileStream;

  try {
    if (!existsSync(LOG_DIR)) mkdirSync(LOG_DIR, { recursive: true });
    const filePath = join(LOG_DIR, `${LOG_FILE_PREFIX}.${today}.log`);
    fileStream = createWriteStream(filePath, { flags: 'a' });
    currentDateStr = today;
    return fileStream;
  } catch {
    // Silently continue without file logging (e.g. permission issue)
    return null;
  }
}

// ---------------------------------------------------------------------------
// Pino logger
// ---------------------------------------------------------------------------
const logger = pino({
  level: 'info',
  formatters: {
    level(label) {
      return { level: label };
    },
  },
  timestamp: pino.stdTimeFunctions.isoTime,
  // In production Docker we write plain JSON to stdout;
  // pino-pretty can be used during dev via `pino-pretty` pipe.
});

// ---------------------------------------------------------------------------
// Log level mapping (matches Python worker levels)
// ---------------------------------------------------------------------------
type LogLevel = 'DEBUG' | 'INFO' | 'WARNING' | 'ERROR' | 'CRITICAL' | 'SUCCESS';

const LEVEL_MAP: Record<LogLevel, keyof pino.Logger> = {
  DEBUG: 'debug',
  INFO: 'info',
  WARNING: 'warn',
  ERROR: 'error',
  CRITICAL: 'fatal',
  SUCCESS: 'info',
};

// ---------------------------------------------------------------------------
// Public API – mirrors Python's  log(message, level, worker_name)
// ---------------------------------------------------------------------------
export function log(
  message: string,
  level: LogLevel = 'INFO',
  workerName = 'unified-worker',
): void {
  const prefix = level === 'SUCCESS' ? '[SUCCESS] ' : '';
  const formatted = `[${workerName}] ${prefix}${message}`;

  // Pino
  const method = LEVEL_MAP[level] ?? 'info';
  (logger as any)[method](formatted);

  // File (best-effort)
  const stream = ensureFileStream();
  if (stream) {
    const ts = new Date().toISOString().replace('T', ' ').slice(0, 19);
    const line = `[${ts}] [${level}] [${workerName}] ${prefix}${message}\n`;
    stream.write(line);
  }
}