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

const MAX_PROFILE_PHOTO_SIZE_BYTES = 5 * 1024 * 1024;
const PROFILE_UPLOADS_DIR = path.resolve(__dirname, '..', '..', 'uploads', 'profile');
const ALLOWED_MIME_TYPES = new Set(['image/jpeg', 'image/png']);

const ensureProfileUploadsDir = () => {
    fs.mkdirSync(PROFILE_UPLOADS_DIR, { recursive: true });
};

const sanitizeFileBaseName = (originalName) => {
    const baseName = path.basename(originalName || 'profile_photo', path.extname(originalName || ''));
    const sanitized = baseName
        .replace(/[^a-zA-Z0-9_-]/g, '_')
        .replace(/_+/g, '_')
        .replace(/^_+|_+$/g, '')
        .slice(0, 40);

    return sanitized || 'profile_photo';
};

const getExtensionFromMimeType = (mimeType) => (mimeType === 'image/png' ? '.png' : '.jpg');

const storage = multer.diskStorage({
    destination: (req, file, cb) => {
        try {
            ensureProfileUploadsDir();
            cb(null, PROFILE_UPLOADS_DIR);
        } catch (error) {
            cb(error);
        }
    },
    filename: (req, file, cb) => {
        const safeBaseName = sanitizeFileBaseName(file.originalname);
        const uniqueSuffix = `${Date.now()}_${crypto.randomBytes(6).toString('hex')}`;
        const extension = getExtensionFromMimeType(file.mimetype);
        cb(null, `${safeBaseName}_${uniqueSuffix}${extension}`);
    }
});

const internalUpload = multer({
    storage,
    limits: {
        fileSize: MAX_PROFILE_PHOTO_SIZE_BYTES,
        files: 1
    },
    fileFilter: (req, file, cb) => {
        if (!ALLOWED_MIME_TYPES.has(file.mimetype)) {
            return cb(new Error('INVALID_FILE_TYPE'));
        }

        cb(null, true);
    }
});

const uploadProfilePhoto = (req, res, next) => {
    internalUpload.single('foto_perfil')(req, res, (error) => {
        if (!error) {
            return next();
        }

        if (error instanceof multer.MulterError) {
            if (error.code === 'LIMIT_FILE_SIZE') {
                return res.status(400).json({ error: 'Archivo demasiado grande. Maximo 5MB.' });
            }

            return res.status(400).json({ error: 'Archivo invalido.' });
        }

        if (error.message === 'INVALID_FILE_TYPE') {
            return res.status(400).json({ error: 'Tipo de archivo invalido. Solo se permite image/jpeg o image/png.' });
        }

        console.error('Error uploading profile photo:', error);
        return res.status(500).json({ error: 'Internal server error' });
    });
};

module.exports = {
    uploadProfilePhoto
};