const path = require('path');
const fs = require('fs');
const crypto = require('crypto');
const multer = require('multer');

// Builds a filename multer can never be tricked into escaping the upload
// directory with — extension only, no attacker-controlled path segments.
// (file.originalname is untrusted; joining it into a path allows `../` traversal.)
function safeFilename(prefix, ext) {
    return `${prefix}-${Date.now()}-${crypto.randomBytes(8).toString('hex')}${ext}`;
}

// Setup multer storage
const storage = multer.diskStorage({
    destination: function (req, file, cb) {
        const uploadPath = path.join(__dirname, '..', '..','public', 'uploads', 'events');
        
        // Check if the upload location exists
        try {
            if (!fs.existsSync(uploadPath)) {
                console.log(`Upload directory does not exist. Creating: ${uploadPath}`);
                fs.mkdirSync(uploadPath, { recursive: true });
            } else {
                // Verify we have write permissions to the directory
                fs.accessSync(uploadPath, fs.constants.W_OK);
                console.log(`Upload directory exists and is writable: ${uploadPath}`);
            }
            cb(null, uploadPath);
        } catch (error) {
            console.error(`Error with upload directory: ${error.message}`);
            cb(new Error(`Cannot access upload directory: ${error.message}`));
        }
    },
    filename: function (req, file, cb) {
        cb(null, safeFilename('event', path.extname(file.originalname).toLowerCase()));
    }
});

// Multer middleware
const upload = multer({
    storage,
    limits: { fileSize: 5 * 1024 * 1024 }, // 5MB max
    fileFilter: function (req, file, cb) {
        const ext = path.extname(file.originalname).toLowerCase();
        if (!['.jpg', '.jpeg', '.png', '.webp', '.gif'].includes(ext)) {
            return cb(new Error('Only images are allowed'), false);
        }
        cb(null, true);
    }
});

// Logo storage (separate subfolder)
const logoStorage = multer.diskStorage({
    destination: function (req, file, cb) {
        const uploadPath = path.join(__dirname, '..', '..', 'public', 'uploads', 'branding');
        try {
            if (!fs.existsSync(uploadPath)) fs.mkdirSync(uploadPath, { recursive: true });
            cb(null, uploadPath);
        } catch (error) {
            cb(new Error(`Cannot access upload directory: ${error.message}`));
        }
    },
    filename: function (req, file, cb) {
        cb(null, safeFilename('logo', path.extname(file.originalname).toLowerCase()));
    }
});

const uploadLogo = multer({
    storage: logoStorage,
    limits: { fileSize: 2 * 1024 * 1024 }, // 2 MB
    fileFilter: function (req, file, cb) {
        const ext = path.extname(file.originalname).toLowerCase();
        if (!['.jpg', '.jpeg', '.png', '.webp', '.svg'].includes(ext)) {
            return cb(new Error('Only image files are allowed'), false);
        }
        cb(null, true);
    }
});

// Favicon storage (same subfolder as the logo — both are "branding" assets)
const faviconStorage = multer.diskStorage({
    destination: function (req, file, cb) {
        const uploadPath = path.join(__dirname, '..', '..', 'public', 'uploads', 'branding');
        try {
            if (!fs.existsSync(uploadPath)) fs.mkdirSync(uploadPath, { recursive: true });
            cb(null, uploadPath);
        } catch (error) {
            cb(new Error(`Cannot access upload directory: ${error.message}`));
        }
    },
    filename: function (req, file, cb) {
        cb(null, safeFilename('favicon', path.extname(file.originalname).toLowerCase()));
    }
});

const uploadFavicon = multer({
    storage: faviconStorage,
    limits: { fileSize: 2 * 1024 * 1024 }, // 2 MB
    fileFilter: function (req, file, cb) {
        const ext = path.extname(file.originalname).toLowerCase();
        if (!['.ico', '.png', '.svg'].includes(ext)) {
            return cb(new Error('Only .ico, .png, or .svg files are allowed for the favicon'), false);
        }
        cb(null, true);
    }
});

// Controller function
const uploadEventImage = (req, res) => {
    // Check for multer errors which would be passed in req.multerError
    if (req.multerError) {
        return res.status(500).json({ message: `Upload failed: ${req.multerError.message}` });
    }

    if (!req.file) {
        return res.status(400).json({ message: 'No file uploaded' });
    }

    const imageUrl = `/uploads/events/${req.file.filename}`;
    res.status(200).json({ url: imageUrl });
};

const uploadLogoImage = (req, res) => {
    if (req.multerError) {
        return res.status(500).json({ message: `Upload failed: ${req.multerError.message}` });
    }
    if (!req.file) {
        return res.status(400).json({ message: 'No file uploaded' });
    }
    res.status(200).json({ url: `/uploads/branding/${req.file.filename}` });
};

const uploadFaviconImage = (req, res) => {
    if (req.multerError) {
        return res.status(500).json({ message: `Upload failed: ${req.multerError.message}` });
    }
    if (!req.file) {
        return res.status(400).json({ message: 'No file uploaded' });
    }
    res.status(200).json({ url: `/uploads/branding/${req.file.filename}` });
};

module.exports = {
    upload,
    uploadEventImage,
    uploadLogo,
    uploadLogoImage,
    uploadFavicon,
    uploadFaviconImage,
};