const rateLimit = require('express-rate-limit');
const helmet = require('helmet');
const { body, param, query } = require('express-validator');

// Rate limiting configuration
const createRateLimit = (windowMs = 15 * 60 * 1000, max = 100) => rateLimit({
    windowMs,
    max,
    message: 'Too many requests from this IP, please try again later.',
    standardHeaders: true,
    legacyHeaders: false,
});

// API rate limits
const apiLimiter = createRateLimit(
    parseInt(process.env.RATE_LIMIT_WINDOW_MS) || 15 * 60 * 1000, // 15 minutes
    parseInt(process.env.RATE_LIMIT_MAX_REQUESTS) || 100
);

// Stricter rate limit for uploads
const uploadLimiter = createRateLimit(
    15 * 60 * 1000, // 15 minutes
    10 // 10 uploads per window
);

// Security headers configuration
const securityHeaders = helmet({
    contentSecurityPolicy: {
        directives: {
            defaultSrc: ["'self'"],
            styleSrc: ["'self'", "'unsafe-inline'"],
            scriptSrc: ["'self'", "https://cdn.jsdelivr.net", "https://unpkg.com"],
            imgSrc: ["'self'", "data:", "blob:"],
            connectSrc: ["'self'"],
            fontSrc: ["'self'"],
            objectSrc: ["'none'"],
            mediaSrc: ["'self'"],
            frameSrc: ["'none'"],
        },
    },
    crossOriginEmbedderPolicy: false, // Required for Three.js
});

// Input validation schemas
const fileValidation = [
    body('description').optional().isLength({ max: 500 }).trim().escape(),
    body('tags').optional().isLength({ max: 200 }).trim(),
    body('printSettings').optional().isJSON(),
    body('dimensions').optional().isJSON(),
];

const fileIdValidation = [
    param('id').isInt({ min: 1 }).withMessage('Valid file ID required')
];

const searchValidation = [
    query('search').optional().isLength({ max: 100 }).trim().escape(),
    query('limit').optional().isInt({ min: 1, max: 100 }).withMessage('Limit must be between 1 and 100'),
    query('offset').optional().isInt({ min: 0 }).withMessage('Offset must be non-negative')
];

module.exports = {
    apiLimiter,
    uploadLimiter,
    securityHeaders,
    fileValidation,
    fileIdValidation,
    searchValidation
};