telegram-management-system/marketing-agent/services/user-management/src/middleware/errorHandler.js

import { logger } from '../utils/logger.js';

export const errorHandler = (err, req, res, next) => {
    // Log error
    logger.error('Error occurred:', {
        error: err.message,
        stack: err.stack,
        url: req.url,
        method: req.method,
        body: req.body,
        params: req.params,
        query: req.query
    });

    // Mongoose validation error
    if (err.name === 'ValidationError') {
        const errors = Object.values(err.errors).map(e => e.message);
        return res.status(400).json({
            error: 'Validation failed',
            details: errors
        });
    }

    // Mongoose duplicate key error
    if (err.code === 11000) {
        const field = Object.keys(err.keyPattern)[0];
        return res.status(400).json({
            error: 'Duplicate value',
            field,
            message: `${field} already exists`
        });
    }

    // Mongoose cast error
    if (err.name === 'CastError') {
        return res.status(400).json({
            error: 'Invalid ID format',
            field: err.path,
            value: err.value
        });
    }

    // JWT errors
    if (err.name === 'JsonWebTokenError') {
        return res.status(401).json({
            error: 'Invalid token'
        });
    }

    if (err.name === 'TokenExpiredError') {
        return res.status(401).json({
            error: 'Token expired'
        });
    }

    // Custom business logic errors
    if (err.message.includes('not found')) {
        return res.status(404).json({
            error: err.message
        });
    }

    if (err.message.includes('already exists')) {
        return res.status(409).json({
            error: err.message
        });
    }

    if (err.message.includes('Cannot') || err.message.includes('Invalid')) {
        return res.status(400).json({
            error: err.message
        });
    }

    // Default error
    res.status(err.status || 500).json({
        error: err.message || 'Internal server error',
        ...(process.env.NODE_ENV === 'development' && { stack: err.stack })
    });
};