const { body, param, query, validationResult } = require('express-validator');

// Input validation middleware
const handleValidationErrors = (req, res, next) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ 
      error: 'Validation failed', 
      details: errors.array() 
    });
  }
  next();
};

// User registration validation
const validateUserRegistration = [
  body('email').isEmail().normalizeEmail(),
  body('password').isLength({ min: 8 }).withMessage('Password must be at least 8 characters'),
  body('firstName').trim().isLength({ min: 1, max: 100 }),
  body('lastName').trim().isLength({ min: 1, max: 100 }),
  body('role').isIn(['admin', 'recruiter', 'employer', 'candidate']),
  handleValidationErrors
];

// Job creation validation
const validateJobCreation = [
  body('title').trim().isLength({ min: 1, max: 200 }),
  body('description').trim().isLength({ min: 1, max: 5000 }),
  body('location').trim().isLength({ min: 1, max: 200 }),
  body('salaryMin').optional().isInt({ min: 0 }),
  body('salaryMax').optional().isInt({ min: 0 }),
  body('experienceLevel').isIn(['entry', 'mid', 'senior', 'executive']),
  body('employmentType').isIn(['full-time', 'part-time', 'contract', 'internship']),
  handleValidationErrors
];

// UUID parameter validation
const validateUUID = [
  param('id').isUUID(),
  handleValidationErrors
];

// Pagination validation
const validatePagination = [
  query('page').optional().isInt({ min: 1 }),
  query('limit').optional().isInt({ min: 1, max: 100 }),
  handleValidationErrors
];

// File upload validation
const validateFileUpload = (req, res, next) => {
  if (!req.file) {
    return res.status(400).json({ error: 'No file uploaded' });
  }
  
  const allowedTypes = [
    'application/pdf',
    'application/msword',
    'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
    'text/plain'
  ];
  
  if (!allowedTypes.includes(req.file.mimetype)) {
    return res.status(400).json({ error: 'Invalid file type' });
  }
  
  if (req.file.size > 10 * 1024 * 1024) { // 10MB limit
    return res.status(400).json({ error: 'File size too large' });
  }
  
  next();
};

module.exports = {
  handleValidationErrors,
  validateUserRegistration,
  validateJobCreation,
  validateUUID,
  validatePagination,
  validateFileUpload
};