const logger = require('../utils/logger');

const errorHandler = (err, req, res, next) => {
  let error = { ...err };
  error.message = err.message;

  // Log error
  logger.error(err);

  // Mongoose bad ObjectId
  if (err.name === 'CastError') {
    const message = 'Resource not found';
    error = { message, statusCode: 404 };
  }

  // Mongoose duplicate key
  if (err.code === 11000) {
    const message = 'Duplicate field value entered';
    error = { message, statusCode: 400 };
  }

  // Mongoose validation error
  if (err.name === 'ValidationError') {
    const message = Object.values(err.errors).map(val => val.message).join(', ');
    error = { message, statusCode: 400 };
  }

  // Sequelize validation error
  if (err.name === 'SequelizeValidationError') {
    const message = err.errors.map(e => e.message).join(', ');
    error = { message, statusCode: 400 };
  }

  // Sequelize unique constraint error
  if (err.name === 'SequelizeUniqueConstraintError') {
    const message = 'Duplicate field value entered';
    error = { message, statusCode: 400 };
  }

  // JWT errors
  if (err.name === 'JsonWebTokenError') {
    const message = 'Invalid token';
    error = { message, statusCode: 401 };
  }

  if (err.name === 'TokenExpiredError') {
    const message = 'Token expired';
    error = { message, statusCode: 401 };
  }

  res.status(error.statusCode || 500).json({
    success: false,
    error: error.message || 'Server Error',
    ...(process.env.NODE_ENV === 'development' && { stack: err.stack })
  });
};

module.exports = errorHandler;