const winston = require('winston');
const path = require('path');
const fs = require('fs');

// Ensure logs directory exists
const logsDir = path.join(__dirname, '../../logs');
if (!fs.existsSync(logsDir)) {
  fs.mkdirSync(logsDir, { recursive: true, mode: 0o755 });
}

/**
 * Custom format to sanitize sensitive data from logs
 * Removes passwords, tokens, secrets, and other sensitive information
 */
const sanitizeFormat = winston.format((info) => {
  // Convert info to string for pattern matching
  const infoStr = JSON.stringify(info);
  
  // Patterns to redact
  const sensitivePatterns = [
    { pattern: /"password"\s*:\s*"[^"]*"/gi, replacement: '"password":"[REDACTED]"' },
    { pattern: /"token"\s*:\s*"[^"]*"/gi, replacement: '"token":"[REDACTED]"' },
    { pattern: /"secret"\s*:\s*"[^"]*"/gi, replacement: '"secret":"[REDACTED]"' },
    { pattern: /"apiKey"\s*:\s*"[^"]*"/gi, replacement: '"apiKey":"[REDACTED]"' },
    { pattern: /"api_key"\s*:\s*"[^"]*"/gi, replacement: '"api_key":"[REDACTED]"' },
    { pattern: /"authorization"\s*:\s*"Bearer\s+[^"]*"/gi, replacement: '"authorization":"Bearer [REDACTED]"' },
    { pattern: /"privateKey"\s*:\s*"[^"]*"/gi, replacement: '"privateKey":"[REDACTED]"' },
    { pattern: /"private_key"\s*:\s*"[^"]*"/gi, replacement: '"private_key":"[REDACTED]"' }
  ];
  
  let sanitized = infoStr;
  sensitivePatterns.forEach(({ pattern, replacement }) => {
    sanitized = sanitized.replace(pattern, replacement);
  });
  
  try {
    return JSON.parse(sanitized);
  } catch (e) {
    return info; // Return original if parsing fails
  }
});

/**
 * Production format: Structured JSON logs without sensitive data
 */
const productionFormat = winston.format.combine(
  winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
  winston.format.errors({ stack: true }),
  sanitizeFormat(),
  winston.format.json()
);

/**
 * Development format: Human-readable with colors
 */
const developmentFormat = winston.format.combine(
  winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
  winston.format.errors({ stack: true }),
  sanitizeFormat(),
  winston.format.colorize(),
  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;
  })
);

const isProduction = process.env.NODE_ENV === 'production';

const logger = winston.createLogger({
  level: process.env.LOG_LEVEL || (isProduction ? 'info' : 'debug'),
  format: productionFormat,
  defaultMeta: { service: 'streamflow-iptv' },
  transports: [
    // Error logs - separate file for errors only
    new winston.transports.File({ 
      filename: path.join(logsDir, 'error.log'), 
      level: 'error',
      maxsize: 5242880, // 5MB
      maxFiles: 5,
      tailable: true
    }),
    // Combined logs - all levels
    new winston.transports.File({ 
      filename: path.join(logsDir, 'combined.log'),
      maxsize: 5242880, // 5MB
      maxFiles: 5,
      tailable: true
    })
  ],
  // Don't exit on uncaught exceptions
  exitOnError: false
});

// Console transport for development
if (!isProduction) {
  logger.add(new winston.transports.Console({
    format: developmentFormat,
    handleExceptions: true
  }));
}

// Security audit log helper
logger.security = (action, details) => {
  logger.info('SECURITY_EVENT', {
    action,
    timestamp: new Date().toISOString(),
    ...details
  });
};

// Performance monitoring helper
logger.performance = (operation, duration, details = {}) => {
  logger.info('PERFORMANCE', {
    operation,
    duration_ms: duration,
    timestamp: new Date().toISOString(),
    ...details
  });
};

module.exports = logger;