/**
 * Production Logger with Winston
 *
 * Provides structured logging for development and production environments.
 * - Console logging for development with colors
 * - File logging for production with rotation
 * - JSON format for production log aggregation
 */

import winston from 'winston';
import path from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const isProduction = process.env.NODE_ENV === 'production';
const logLevel = process.env.LOG_LEVEL || (isProduction ? 'info' : 'debug');

/**
 * Custom format for development console output
 */
const devFormat = winston.format.combine(
  winston.format.colorize(),
  winston.format.timestamp({ format: 'HH:mm:ss' }),
  winston.format.printf(({ timestamp, level, message, ...meta }) => {
    let msg = `${timestamp} [${level}] ${message}`;
    if (Object.keys(meta).length > 0) {
      msg += ` ${JSON.stringify(meta, null, 2)}`;
    }
    return msg;
  })
);

/**
 * Format for production (JSON for log aggregation)
 */
const prodFormat = winston.format.combine(
  winston.format.timestamp(),
  winston.format.errors({ stack: true }),
  winston.format.json()
);

/**
 * Create Winston logger instance
 */
const logger = winston.createLogger({
  level: logLevel,
  format: isProduction ? prodFormat : devFormat,
  defaultMeta: {
    service: 'pokedex-backend',
    environment: process.env.NODE_ENV
  },
  transports: []
});

// Console transport (always enabled)
logger.add(
  new winston.transports.Console({
    format: isProduction ? prodFormat : devFormat
  })
);

// File transports for production
if (isProduction) {
  // All logs
  logger.add(
    new winston.transports.File({
      filename: path.join(__dirname, '../logs/combined.log'),
      maxsize: 5242880, // 5MB
      maxFiles: 5
    })
  );

  // Error logs
  logger.add(
    new winston.transports.File({
      filename: path.join(__dirname, '../logs/error.log'),
      level: 'error',
      maxsize: 5242880, // 5MB
      maxFiles: 5
    })
  );
}

/**
 * Express middleware for HTTP request logging
 */
export function requestLogger(req, res, next) {
  const start = Date.now();

  // Log request
  logger.info('HTTP Request', {
    method: req.method,
    url: req.url,
    ip: req.ip,
    userAgent: req.get('user-agent')
  });

  // Log response when finished
  res.on('finish', () => {
    const duration = Date.now() - start;
    const logLevel = res.statusCode >= 400 ? 'warn' : 'info';

    logger[logLevel]('HTTP Response', {
      method: req.method,
      url: req.url,
      status: res.statusCode,
      duration: `${duration}ms`
    });
  });

  next();
}

/**
 * Express error logging middleware
 */
export function errorLogger(err, req, res, next) {
  logger.error('Express Error', {
    error: err.message,
    stack: err.stack,
    method: req.method,
    url: req.url,
    body: req.body
  });

  next(err);
}

/**
 * Log uncaught exceptions and unhandled rejections
 */
process.on('uncaughtException', error => {
  logger.error('Uncaught Exception', {
    error: error.message,
    stack: error.stack
  });
  // Give logger time to write before exiting
  setTimeout(() => process.exit(1), 1000);
});

process.on('unhandledRejection', (reason, promise) => {
  logger.error('Unhandled Rejection', {
    reason: reason instanceof Error ? reason.message : reason,
    stack: reason instanceof Error ? reason.stack : undefined
  });
});

export default logger;