server.js

const express = require('express');
const cors = require('cors');
const fs = require('fs').promises;
const path = require('path');
const crypto = require('crypto');

const app = express();
const PORT = 3000;

// CORS тохиргоо - Live Server-тэй ажиллана
app.use(cors({
    origin: '*', // Бүх domain-ээс зөвшөөрнө
    methods: ['GET', 'POST', 'PUT', 'DELETE'],
    allowedHeaders: ['Content-Type']
}));

app.use(express.json());

// Serve static files (HTML, CSS, JS, images, fonts)
app.use(express.static(__dirname));

// Root route - serve index.html
app.get('/', (req, res) => {
    res.sendFile(path.join(__dirname, 'index.html'));
});

// JSON файлуудын зам
const DATA_DIR = path.join(__dirname, 'data');
const FILES = {
    USERS: path.join(DATA_DIR, 'users.json'),
    PRODUCTS: path.join(DATA_DIR, 'products.json'),
    CARTS: path.join(DATA_DIR, 'carts.json'),
    ORDERS: path.join(DATA_DIR, 'orders.json')
};

// Ensure data directory exists
async function ensureDataDir() {
    try {
        await fs.mkdir(DATA_DIR, { recursive: true });
    } catch (error) {
        console.error('Error creating data directory:', error);
    }
}

// Password хашлах
function hashPassword(password) {
    return crypto.createHash('sha256').update(password).digest('hex');
}

// Generic file read function
async function readFile(filepath, defaultValue = []) {
    try {
        const data = await fs.readFile(filepath, 'utf8');
        return JSON.parse(data);
    } catch (error) {
        return defaultValue;
    }
}

// Generic file write function
async function writeFile(filepath, data) {
    await fs.writeFile(filepath, JSON.stringify(data, null, 2));
}

// Initialize default data
async function initializeData() {
    const defaultProducts = [
        {
            id: '1',
            name: 'Surron Light Bee X Controller',
            category: 'Electronics',
            price: 899.99,
            stock: 15,
            image: 'https://images.unsplash.com/photo-1558618666-fcd25c85cd64?w=500',
            description: 'High-performance controller for Surron Light Bee X. Advanced motor control with regenerative braking.'
        },
        {
            id: '2',
            name: 'Premium Battery Pack 60V',
            category: 'Battery',
            price: 1299.99,
            stock: 8,
            image: 'https://images.unsplash.com/photo-1609976699759-45cf02366b23?w=500',
            description: '60V 32Ah Lithium-ion battery pack. Extended range up to 60 miles per charge.'
        },
        {
            id: '3',
            name: 'Front Suspension Fork',
            category: 'Suspension',
            price: 549.99,
            stock: 12,
            image: 'https://images.unsplash.com/photo-1532298229144-0ec0c57515c7?w=500',
            description: 'DNM USD-8 inverted front fork. 43mm stanchions with adjustable compression and rebound.'
        },
        {
            id: '4',
            name: 'Rear Shock Absorber',
            category: 'Suspension',
            price: 399.99,
            stock: 10,
            image: 'https://images.unsplash.com/photo-1558618666-fcd25c85cd64?w=500',
            description: 'DNM AO-38RC rear shock. 190mm eye-to-eye with lockout feature.'
        },
        {
            id: '5',
            name: 'Hydraulic Brake Set',
            category: 'Brakes',
            price: 279.99,
            stock: 20,
            image: 'https://images.unsplash.com/photo-1486262715619-67b85e0b08d3?w=500',
            description: 'Front and rear hydraulic disc brakes. 180mm rotors with 4-piston calipers.'
        },
        {
            id: '6',
            name: 'Performance Tires Set',
            category: 'Wheels',
            price: 189.99,
            stock: 25,
            image: 'https://images.unsplash.com/photo-1624379329795-89eac93ecd3f?w=500',
            description: 'Aggressive tread pattern tires. Excellent grip for off-road and street riding.'
        },
        {
            id: '7',
            name: 'LED Headlight Kit',
            category: 'Accessories',
            price: 129.99,
            stock: 30,
            image: 'https://images.unsplash.com/photo-1542838309-ab4f5d3c2a18?w=500',
            description: 'Ultra-bright LED headlight with high and low beam. 2000 lumens output.'
        },
        {
            id: '8',
            name: 'Custom Seat',
            category: 'Accessories',
            price: 149.99,
            stock: 18,
            image: 'https://images.unsplash.com/photo-1558618666-fcd25c85cd64?w=500',
            description: 'Ergonomic custom seat with enhanced padding. Weather-resistant material.'
        }
    ];

    const defaultUsers = [
        {
            id: '1',
            username: 'gank',
            email: 'gank@surron.mn',
            password: hashPassword('Gank2024!'),
            role: 'admin',
            createdAt: new Date().toISOString()
        }
    ];

    const products = await readFile(FILES.PRODUCTS);
    if (products.length === 0) {
        await writeFile(FILES.PRODUCTS, defaultProducts);
        console.log('✅ Default бүтээгдэхүүнүүд нэмэгдлээ');
    }

    const users = await readFile(FILES.USERS);
    if (users.length === 0) {
        await writeFile(FILES.USERS, defaultUsers);
        console.log('✅ Default admin: gank / Gank2024!');
    }

    await readFile(FILES.CARTS);
    await readFile(FILES.ORDERS);
}

// ==================== AUTH ====================

app.post('/api/auth/register', async (req, res) => {
    try {
        const { username, email, password } = req.body;

        if (!username || !email || !password) {
            return res.status(400).json({ 
                success: false, 
                message: 'Бүх талбарыг бөглөнө үү' 
            });
        }

        const users = await readFile(FILES.USERS);
        const exists = users.find(u => u.username === username || u.email === email);
        
        if (exists) {
            return res.status(400).json({ 
                success: false, 
                message: 'Хэрэглэгч аль хэдийн бүртгэлтэй байна' 
            });
        }

        const newUser = {
            id: Date.now().toString(),
            username,
            email,
            password: hashPassword(password),
            role: 'user',
            createdAt: new Date().toISOString()
        };

        users.push(newUser);
        await writeFile(FILES.USERS, users);

        const { password: _, ...userWithoutPassword } = newUser;
        res.status(201).json({
            success: true,
            message: 'Амжилттай бүртгэгдлээ',
            data: { user: userWithoutPassword }
        });
    } catch (error) {
        console.error('Register error:', error);
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.post('/api/auth/login', async (req, res) => {
    try {
        const { username, password } = req.body;

        if (!username || !password) {
            return res.status(400).json({ 
                success: false, 
                message: 'Нэр болон нууц үг оруулна уу' 
            });
        }

        const users = await readFile(FILES.USERS);
        const user = users.find(u => u.username === username && u.password === hashPassword(password));

        if (!user) {
            return res.status(401).json({ 
                success: false, 
                message: 'Нэр эсвэл нууц үг буруу байна' 
            });
        }

        const { password: _, ...userWithoutPassword } = user;
        res.json({
            success: true,
            message: 'Амжилттай нэвтэрлээ',
            data: { user: userWithoutPassword }
        });
    } catch (error) {
        console.error('Login error:', error);
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

// ==================== PRODUCTS ====================

app.get('/api/products', async (req, res) => {
    try {
        const { category, search } = req.query;
        let products = await readFile(FILES.PRODUCTS);

        if (category && category !== 'All') {
            products = products.filter(p => p.category === category);
        }

        if (search) {
            const searchLower = search.toLowerCase();
            products = products.filter(p => 
                p.name.toLowerCase().includes(searchLower) || 
                p.description.toLowerCase().includes(searchLower)
            );
        }

        res.json({
            success: true,
            count: products.length,
            data: products
        });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.get('/api/products/:id', async (req, res) => {
    try {
        const products = await readFile(FILES.PRODUCTS);
        const product = products.find(p => p.id === req.params.id);

        if (!product) {
            return res.status(404).json({ success: false, message: 'Бүтээгдэхүүн олдсонгүй' });
        }

        res.json({ success: true, data: product });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.post('/api/products', async (req, res) => {
    try {
        const products = await readFile(FILES.PRODUCTS);
        const newProduct = {
            id: Date.now().toString(),
            ...req.body,
            createdAt: new Date().toISOString()
        };

        products.push(newProduct);
        await writeFile(FILES.PRODUCTS, products);

        res.status(201).json({
            success: true,
            message: 'Бүтээгдэхүүн амжилттай нэмэгдлээ',
            data: newProduct
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.put('/api/products/:id', async (req, res) => {
    try {
        const products = await readFile(FILES.PRODUCTS);
        const index = products.findIndex(p => p.id === req.params.id);

        if (index === -1) {
            return res.status(404).json({ success: false, message: 'Бүтээгдэхүүн олдсонгүй' });
        }

        products[index] = {
            ...products[index],
            ...req.body,
            id: req.params.id,
            updatedAt: new Date().toISOString()
        };

        await writeFile(FILES.PRODUCTS, products);

        res.json({
            success: true,
            message: 'Бүтээгдэхүүн амжилттай шинэчлэгдлээ',
            data: products[index]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.delete('/api/products/:id', async (req, res) => {
    try {
        let products = await readFile(FILES.PRODUCTS);
        const initialLength = products.length;
        
        products = products.filter(p => p.id !== req.params.id);

        if (products.length === initialLength) {
            return res.status(404).json({ success: false, message: 'Бүтээгдэхүүн олдсонгүй' });
        }

        await writeFile(FILES.PRODUCTS, products);

        res.json({
            success: true,
            message: 'Бүтээгдэхүүн амжилттай устгагдлаа'
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

// ==================== CART ====================

app.get('/api/cart/:userId', async (req, res) => {
    try {
        const carts = await readFile(FILES.CARTS);
        const cart = carts.find(c => c.userId === req.params.userId);

        res.json({
            success: true,
            data: cart || { userId: req.params.userId, items: [] }
        });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.post('/api/cart/:userId/add', async (req, res) => {
    try {
        const { productId, quantity = 1 } = req.body;
        const carts = await readFile(FILES.CARTS);
        const products = await readFile(FILES.PRODUCTS);

        const product = products.find(p => p.id === productId);
        if (!product) {
            return res.status(404).json({ success: false, message: 'Бүтээгдэхүүн олдсонгүй' });
        }

        let cartIndex = carts.findIndex(c => c.userId === req.params.userId);
        
        if (cartIndex === -1) {
            carts.push({
                userId: req.params.userId,
                items: [],
                updatedAt: new Date().toISOString()
            });
            cartIndex = carts.length - 1;
        }

        const itemIndex = carts[cartIndex].items.findIndex(i => i.productId === productId);

        if (itemIndex > -1) {
            carts[cartIndex].items[itemIndex].quantity += quantity;
        } else {
            carts[cartIndex].items.push({
                productId,
                quantity,
                addedAt: new Date().toISOString()
            });
        }

        carts[cartIndex].updatedAt = new Date().toISOString();
        await writeFile(FILES.CARTS, carts);

        res.json({
            success: true,
            message: 'Сагсанд нэмэгдлээ',
            data: carts[cartIndex]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.put('/api/cart/:userId/update', async (req, res) => {
    try {
        const { productId, quantity } = req.body;
        const carts = await readFile(FILES.CARTS);
        const cartIndex = carts.findIndex(c => c.userId === req.params.userId);

        if (cartIndex === -1) {
            return res.status(404).json({ success: false, message: 'Сагс олдсонгүй' });
        }

        const itemIndex = carts[cartIndex].items.findIndex(i => i.productId === productId);

        if (itemIndex === -1) {
            return res.status(404).json({ success: false, message: 'Бүтээгдэхүүн сагсанд байхгүй' });
        }

        if (quantity <= 0) {
            carts[cartIndex].items.splice(itemIndex, 1);
        } else {
            carts[cartIndex].items[itemIndex].quantity = quantity;
        }

        carts[cartIndex].updatedAt = new Date().toISOString();
        await writeFile(FILES.CARTS, carts);

        res.json({
            success: true,
            message: 'Сагс шинэчлэгдлээ',
            data: carts[cartIndex]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.delete('/api/cart/:userId/remove/:productId', async (req, res) => {
    try {
        const carts = await readFile(FILES.CARTS);
        const cartIndex = carts.findIndex(c => c.userId === req.params.userId);

        if (cartIndex === -1) {
            return res.status(404).json({ success: false, message: 'Сагс олдсонгүй' });
        }

        carts[cartIndex].items = carts[cartIndex].items.filter(i => i.productId !== req.params.productId);
        carts[cartIndex].updatedAt = new Date().toISOString();
        
        await writeFile(FILES.CARTS, carts);

        res.json({
            success: true,
            message: 'Бүтээгдэхүүн хасагдлаа',
            data: carts[cartIndex]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.delete('/api/cart/:userId/clear', async (req, res) => {
    try {
        const carts = await readFile(FILES.CARTS);
        const cartIndex = carts.findIndex(c => c.userId === req.params.userId);

        if (cartIndex === -1) {
            return res.status(404).json({ success: false, message: 'Сагс олдсонгүй' });
        }

        carts[cartIndex].items = [];
        carts[cartIndex].updatedAt = new Date().toISOString();
        
        await writeFile(FILES.CARTS, carts);

        res.json({
            success: true,
            message: 'Сагс хоосон болгогдлоо',
            data: carts[cartIndex]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

// ==================== ORDERS ====================

app.post('/api/orders', async (req, res) => {
    try {
        const { userId, items, totalAmount, shippingAddress } = req.body;

        const orders = await readFile(FILES.ORDERS);
        const products = await readFile(FILES.PRODUCTS);

        for (const item of items) {
            const product = products.find(p => p.id === item.productId);
            if (!product || product.stock < item.quantity) {
                return res.status(400).json({ 
                    success: false, 
                    message: `${item.name || 'Бүтээгдэхүүн'} хангалттай нөөцгүй` 
                });
            }
            product.stock -= item.quantity;
        }

        await writeFile(FILES.PRODUCTS, products);

        const newOrder = {
            id: Date.now().toString(),
            userId,
            items,
            totalAmount,
            shippingAddress,
            status: 'pending',
            createdAt: new Date().toISOString()
        };

        orders.push(newOrder);
        await writeFile(FILES.ORDERS, orders);

        const carts = await readFile(FILES.CARTS);
        const cartIndex = carts.findIndex(c => c.userId === userId);
        if (cartIndex > -1) {
            carts[cartIndex].items = [];
            await writeFile(FILES.CARTS, carts);
        }

        res.status(201).json({
            success: true,
            message: 'Захиалга амжилттай үүсгэгдлээ',
            data: newOrder
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.get('/api/orders', async (req, res) => {
    try {
        const { userId, role } = req.query;
        let orders = await readFile(FILES.ORDERS);

        if (role !== 'admin' && userId) {
            orders = orders.filter(o => o.userId === userId);
        }

        orders.sort((a, b) => new Date(b.createdAt) - new Date(a.createdAt));

        res.json({
            success: true,
            count: orders.length,
            data: orders
        });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.get('/api/orders/:id', async (req, res) => {
    try {
        const orders = await readFile(FILES.ORDERS);
        const order = orders.find(o => o.id === req.params.id);

        if (!order) {
            return res.status(404).json({ success: false, message: 'Захиалга олдсонгүй' });
        }

        res.json({ success: true, data: order });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.put('/api/orders/:id/status', async (req, res) => {
    try {
        const { status } = req.body;
        const orders = await readFile(FILES.ORDERS);
        const index = orders.findIndex(o => o.id === req.params.id);

        if (index === -1) {
            return res.status(404).json({ success: false, message: 'Захиалга олдсонгүй' });
        }

        orders[index].status = status;
        orders[index].updatedAt = new Date().toISOString();
        
        await writeFile(FILES.ORDERS, orders);

        res.json({
            success: true,
            message: 'Захиалгын төлөв шинэчлэгдлээ',
            data: orders[index]
        });
    } catch (error) {
        res.status(400).json({ success: false, message: 'Алдаа гарлаа' });
    }
});

app.get('/api/orders/stats/dashboard', async (req, res) => {
    try {
        const orders = await readFile(FILES.ORDERS);
        const products = await readFile(FILES.PRODUCTS);

        const totalOrders = orders.length;
        const pendingOrders = orders.filter(o => o.status === 'pending').length;
        const totalRevenue = orders.reduce((sum, order) => sum + (order.totalAmount || 0), 0);
        const productCount = products.length;

        res.json({
            success: true,
            data: {
                totalOrders,
                pendingOrders,
                totalRevenue,
                productCount
            }
        });
    } catch (error) {
        res.status(500).json({ success: false, message: 'Серверийн алдаа' });
    }
});

app.get('/', (req, res) => {
    res.json({ 
        message: '🚀 Surron API ажиллаж байна',
        status: 'OK',
        endpoints: {
            auth: '/api/auth/*',
            products: '/api/products/*',
            cart: '/api/cart/*',
            orders: '/api/orders/*'
        }
    });
});

// Initialize and start
(async () => {
    await ensureDataDir();
    await initializeData();
    
    app.listen(PORT, () => {
        console.log(`\n${'='.repeat(50)}`);
        console.log(`🚀 СЕРВЕР АЖИЛЛАЖ БАЙНА`);
        console.log(`${'='.repeat(50)}`);
        console.log(`📡 URL: http://localhost:${PORT}`);
        console.log(`📁 Data: ${DATA_DIR}`);
        console.log(`✅ CORS: Enabled (бүх domain)`);
        console.log(`👤 Admin: gank / Gank2024!`);
        console.log(`${'='.repeat(50)}\n`);
    });
})();