const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');

const app = express();
app.use(cors());
app.use(express.json());

// MongoDB Connection - FIXED URI with correct cluster ID
const MONGO_URI = "mongodb+srv://ibrohm135:mansur5754@cluster0.intw8qq.mongodb.net/chat_app?retryWrites=true&w=majority";

const connectDB = async () => {
    try {
        await mongoose.connect(MONGO_URI);
        console.log('✅ Connected to MongoDB Atlas');
    } catch (err) {
        console.error('❌ MongoDB Connection Error:', err.message);
        console.log('🔄 Retrying connection in 5 seconds...');
        setTimeout(connectDB, 5000);
    }
};
connectDB();

// --- SCHEMAS ---

// Message Schema (Updated with imageUrl, groupId, isRead)
const MessageSchema = new mongoose.Schema({
    text: String,
    senderId: String,
    senderName: String,
    isAi: Boolean,
    receiverId: String,
    isGroup: Boolean,
    groupId: String,
    imageUrl: String,
    isRead: { type: Boolean, default: false },
    timestamp: { type: Date, default: Date.now }
});
const Message = mongoose.model('Message', MessageSchema);

// User Schema (Added username)
const UserSchema = new mongoose.Schema({
    uid: { type: String, unique: true, required: true },
    email: String,
    displayName: String,
    username: { type: String, unique: true, sparse: true },
    photoURL: String,
    lastLogin: { type: Date, default: Date.now }
});
const User = mongoose.model('User', UserSchema);

// Status (Story) Schema
const StatusSchema = new mongoose.Schema({
    userId: String,
    userName: String,
    userImage: String,
    imageUrl: String,
    type: { type: String, default: 'image' },
    caption: String,
    color: String,
    timestamp: { type: Date, default: Date.now },
    expiresAt: { type: Date, default: () => Date.now() + 24 * 60 * 60 * 1000 }
});
const Status = mongoose.model('Status', StatusSchema);

// --- ROUTES ---

app.get('/', (req, res) => {
    res.json({
        status: 'running',
        message: 'Chat App Server - v17 FINAL (Fixed Connection)',
        endpoints: {
            messages: 'GET/POST /messages',
            users: 'POST /users, GET /users/search',
            status: 'GET/POST /status'
        }
    });
});

// Messages
app.get('/messages', async (req, res) => {
    try {
        const messages = await Message.find().sort({ timestamp: -1 }).limit(100);
        res.json(messages);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

app.post('/messages', async (req, res) => {
    try {
        const { text, senderId, senderName, isAi, receiverId, isGroup, groupId, imageUrl } = req.body;
        const newMessage = new Message({
            text, senderId, senderName, isAi, receiverId, isGroup, groupId, imageUrl
        });
        await newMessage.save();
        res.json(newMessage);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// Get User's Chats (Conversations list with last message and unread count)
app.get('/chats/:userId', async (req, res) => {
    try {
        const { userId } = req.params;

        // Find all messages where user is sender or receiver
        const messages = await Message.find({
            $or: [{ senderId: userId }, { receiverId: userId }]
        }).sort({ timestamp: -1 });

        // Group by conversation partner
        const chatsMap = new Map();

        for (const msg of messages) {
            const partnerId = msg.senderId === userId ? msg.receiverId : msg.senderId;
            if (!partnerId || partnerId === 'AI') continue;

            if (!chatsMap.has(partnerId)) {
                // Get partner info
                const partner = await User.findOne({ uid: partnerId });
                const unreadCount = await Message.countDocuments({
                    senderId: partnerId,
                    receiverId: userId,
                    isRead: false
                });

                chatsMap.set(partnerId, {
                    id: partnerId,
                    name: partner?.displayName || 'Unknown',
                    image: partner?.photoURL || `https://api.dicebear.com/7.x/initials/png?seed=${partner?.displayName || 'U'}`,
                    lastMessage: msg.text || (msg.imageUrl ? '📷 Photo' : ''),
                    time: msg.timestamp,
                    unread: unreadCount,
                    isOnline: partner?.lastLogin ? (Date.now() - new Date(partner.lastLogin).getTime() < 300000) : false
                });
            }
        }

        res.json(Array.from(chatsMap.values()));
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// Mark messages as read
app.post('/messages/read', async (req, res) => {
    try {
        const { senderId, receiverId } = req.body;
        await Message.updateMany(
            { senderId, receiverId, isRead: false },
            { isRead: true }
        );
        res.json({ success: true });
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// User Sync
app.post('/users', async (req, res) => {
    try {
        const { uid, email, displayName, photoURL, username } = req.body;
        const updateData = { email, displayName, photoURL, lastLogin: new Date() };
        if (username) updateData.username = username;

        const user = await User.findOneAndUpdate(
            { uid },
            updateData,
            { new: true, upsert: true }
        );
        res.json(user);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// Search Users
app.get('/users/search', async (req, res) => {
    try {
        const { q } = req.query;
        if (!q) return res.json([]);
        const cleanQ = q.startsWith('@') ? q.substring(1) : q;

        const users = await User.find({
            $or: [
                { displayName: { $regex: cleanQ, $options: 'i' } },
                { email: { $regex: cleanQ, $options: 'i' } },
                { username: { $regex: cleanQ, $options: 'i' } }
            ]
        }).limit(20);
        res.json(users);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// Status Routes
app.get('/status', async (req, res) => {
    try {
        const statuses = await Status.find({ expiresAt: { $gt: new Date() } }).sort({ timestamp: -1 });
        res.json(statuses);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

app.post('/status', async (req, res) => {
    try {
        const { userId, userName, userImage, imageUrl, type, caption, color } = req.body;
        const newStatus = new Status({
            userId, userName, userImage, imageUrl, type, caption, color
        });
        await newStatus.save();
        res.json(newStatus);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
});

// AI Chat Endpoint (using Hugging Face Inference API with Token)
const HF_TOKEN = process.env.HF_TOKEN || '';

app.post('/ai', async (req, res) => {
    try {
        const { text } = req.body;
        if (!text) {
            return res.status(400).json({ error: 'Text is required' });
        }

        // Use Hugging Face Inference API with authentication
        const response = await fetch('https://api-inference.huggingface.co/models/microsoft/DialoGPT-large', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'Authorization': `Bearer ${HF_TOKEN}`
            },
            body: JSON.stringify({
                inputs: text,
                parameters: {
                    max_length: 150,
                    temperature: 0.7
                }
            })
        });

        if (response.ok) {
            const data = await response.json();
            // DialoGPT returns generated text
            let aiText = '';
            if (Array.isArray(data) && data[0]?.generated_text) {
                aiText = data[0].generated_text;
            } else if (data.generated_text) {
                aiText = data.generated_text;
            } else {
                aiText = "Tushundim. Yana nima so'rashni xohlaysiz?";
            }
            res.json({ text: aiText });
        } else {
            console.error('HF API Error:', response.status, await response.text());
            // Fallback response if API fails
            const fallbackResponses = [
                "Salom! Men sizga yordam berishga tayyorman. 😊",
                "Qiziq savol! Batafsil tushuntirib bera olasizmi?",
                "Bu juda yaxshi fikr! Davom eting.",
                "Tushunarli. Yana nima so'rashni xohlaysiz?",
                "Rahmat! Sizga yana qanday yordam bera olaman?"
            ];
            const randomResponse = fallbackResponses[Math.floor(Math.random() * fallbackResponses.length)];
            res.json({ text: randomResponse });
        }
    } catch (e) {
        console.error('AI Error:', e.message);
        res.json({ text: "Uzr, texnik xatolik yuz berdi. Keyinroq urinib ko'ring." });
    }
});

const PORT = process.env.PORT || 7860;
app.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
});