// ============================================================
// QZ TOKEN API SERVER
// ============================================================
// Endpoints för:
// - Zoomer wallet-hantering
// - Token-transaktioner
// - Mission-prissättning
// - Payout-hantering
// - Stripe Connect-integration

const express = require('express');
const { Pool } = require('pg');
const crypto = require('crypto');
const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);

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

// PostgreSQL pool
const pool = new Pool({
    connectionString: process.env.DATABASE_URL,
    ssl: process.env.NODE_ENV === 'production' ? { rejectUnauthorized: false } : false
});

// Konstanta
const QZ_TO_USD_RATE = 1.0; // 1 QZ TOKEN = 1 USD (fast kurs, test)
const MIN_MISSION_PRICE = 0.5; // Minimum $0.50 per mission

// ============================================================
// HJÄLPFUNKTIONER
// ============================================================

function generateTxHash() {
    const timestamp = Date.now();
    const random = crypto.randomBytes(16).toString('hex');
    return `qz_tx_${timestamp}_${random}`;
}

function signTransaction(txData, privateKey) {
    const sign = crypto.createSign('SHA256');
    sign.update(JSON.stringify(txData));
    sign.end();
    return sign.sign(privateKey, 'hex');
}

function qzToUsd(qzAmount) {
    return qzAmount * QZ_TO_USD_RATE;
}

function usdToQz(usdAmount) {
    return usdAmount / QZ_TO_USD_RATE;
}

// ============================================================
// ZOOMER WALLET
// ============================================================

// Skapa wallet för ny Zoomer
app.post('/api/v1/wallets', async (req, res) => {
    const { zoomer_id, stripe_connect_account_id } = req.body;
    
    try {
        const result = await pool.query(
            `INSERT INTO zoomer_wallets (zoomer_id, stripe_connect_account_id, stripe_connect_status)
             VALUES ($1, $2, $3)
             RETURNING *`,
            [zoomer_id, stripe_connect_account_id, stripe_connect_account_id ? 'active' : 'pending']
        );
        
        // Skapa default payout schema (måndagar)
        await pool.query(
            `INSERT INTO payout_schedules (zoomer_id, wallet_id, day_of_week, time_of_day)
             VALUES ($1, $2, 1, '09:00:00')`,
            [zoomer_id, result.rows[0].id]
        );
        
        res.json({
            success: true,
            wallet: result.rows[0]
        });
    } catch (error) {
        console.error('Error creating wallet:', error);
        res.status(500).json({ error: 'Failed to create wallet' });
    }
});

// Hämta wallet-info
app.get('/api/v1/wallets/:zoomer_id', async (req, res) => {
    const { zoomer_id } = req.params;
    
    try {
        const result = await pool.query(
            `SELECT * FROM zoomer_balance WHERE zoomer_id = $1`,
            [zoomer_id]
        );
        
        if (result.rows.length === 0) {
            return res.status(404).json({ error: 'Wallet not found' });
        }
        
        res.json({
            success: true,
            wallet: result.rows[0]
        });
    } catch (error) {
        console.error('Error fetching wallet:', error);
        res.status(500).json({ error: 'Failed to fetch wallet' });
    }
});

// ============================================================
// TOKEN TRANSAKTIONER
// ============================================================

// Skapa mission reward (när uppdrag godkänns)
app.post('/api/v1/transactions/mission-reward', async (req, res) => {
    const { zoomer_id, mission_id, observation_id, amount_qz_token, description } = req.body;
    
    const client = await pool.connect();
    
    try {
        await client.query('BEGIN');
        
        // Hämta wallet
        const walletResult = await client.query(
            `SELECT id FROM zoomer_wallets WHERE zoomer_id = $1`,
            [zoomer_id]
        );
        
        if (walletResult.rows.length === 0) {
            throw new Error('Wallet not found');
        }
        
        const wallet_id = walletResult.rows[0].id;
        const txHash = generateTxHash();
        const amount_usd = qzToUsd(amount_qz_token);
        
        // Skapa transaktion
        const txResult = await client.query(
            `INSERT INTO token_transactions 
             (tx_hash, tx_type, to_wallet_id, amount_qz_token, amount_usd, exchange_rate, mission_id, observation_id, description, status, confirmed_at)
             VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, NOW())
             RETURNING *`,
            [txHash, 'mission_reward', wallet_id, amount_qz_token, amount_usd, QZ_TO_USD_RATE, mission_id, observation_id, description, 'confirmed']
        );
        
        // Uppdatera wallet-balans
        await client.query(
            `UPDATE zoomer_wallets 
             SET balance_qz_token = balance_qz_token + $1
             WHERE id = $2`,
            [amount_qz_token, wallet_id]
        );
        
        await client.query('COMMIT');
        
        res.json({
            success: true,
            transaction: txResult.rows[0],
            message: `Rewarded ${amount_qz_token} QZ TOKEN ($${amount_usd.toFixed(2)}) to zoomer ${zoomer_id}`
        });
    } catch (error) {
        await client.query('ROLLBACK');
        console.error('Error creating mission reward:', error);
        res.status(500).json({ error: 'Failed to create mission reward' });
    } finally {
        client.release();
    }
});

// Hämta transaktionshistorik
app.get('/api/v1/transactions/:zoomer_id', async (req, res) => {
    const { zoomer_id } = req.params;
    const { limit = 50, offset = 0 } = req.query;
    
    try {
        const walletResult = await pool.query(
            `SELECT id FROM zoomer_wallets WHERE zoomer_id = $1`,
            [zoomer_id]
        );
        
        if (walletResult.rows.length === 0) {
            return res.status(404).json({ error: 'Wallet not found' });
        }
        
        const wallet_id = walletResult.rows[0].id;
        
        const result = await pool.query(
            `SELECT * FROM token_transactions 
             WHERE from_wallet_id = $1 OR to_wallet_id = $1
             ORDER BY created_at DESC
             LIMIT $2 OFFSET $3`,
            [wallet_id, limit, offset]
        );
        
        res.json({
            success: true,
            transactions: result.rows
        });
    } catch (error) {
        console.error('Error fetching transactions:', error);
        res.status(500).json({ error: 'Failed to fetch transactions' });
    }
});

// ============================================================
// MISSION PRICING
// ============================================================

// Hämta pris för mission-typ
app.get('/api/v1/pricing/:mission_type', async (req, res) => {
    const { mission_type } = req.params;
    const { country_code, city } = req.query;
    
    try {
        let query = `SELECT * FROM mission_pricing WHERE mission_type = $1 AND status = 'active'`;
        let params = [mission_type];
        
        if (country_code) {
            query += ` AND (country_code = $2 OR country_code IS NULL)`;
            params.push(country_code);
        }
        
        if (city) {
            query += ` AND (city = $3 OR city IS NULL)`;
            params.push(city);
        }
        
        query += ` ORDER BY country_code DESC, city DESC LIMIT 1`;
        
        const result = await pool.query(query, params);
        
        if (result.rows.length === 0) {
            // Returnera default-pris
            return res.json({
                success: true,
                pricing: {
                    mission_type,
                    base_price_qz_token: usdToQz(MIN_MISSION_PRICE),
                    base_price_usd: MIN_MISSION_PRICE,
                    complexity_multiplier: 1.0,
                    min_price_qz_token: usdToQz(MIN_MISSION_PRICE),
                    max_price_qz_token: 100.0
                }
            });
        }
        
        res.json({
            success: true,
            pricing: result.rows[0]
        });
    } catch (error) {
        console.error('Error fetching pricing:', error);
        res.status(500).json({ error: 'Failed to fetch pricing' });
    }
});

// ============================================================
// PAYOUT
// ============================================================

// Initiera payout (körs varje måndag via cron)
app.post('/api/v1/payouts/execute', async (req, res) => {
    const { zoomer_id } = req.body; // Optional: specific zoomer, or all
    
    try {
        // Hitta zoomers med payout idag
        const today = new Date().getDay(); // 1 = Monday
        
        let query = `
            SELECT ps.*, zw.balance_qz_token, zw.stripe_connect_account_id, z.name as zoomer_name
            FROM payout_schedules ps
            JOIN zoomer_wallets zw ON zw.id = ps.wallet_id
            JOIN zoomers z ON z.id = ps.zoomer_id
            WHERE ps.day_of_week = $1 
            AND ps.status = 'active'
            AND zw.stripe_connect_status = 'active'
            AND zw.balance_qz_token >= ps.minimum_qz_token
        `;
        
        let params = [today];
        
        if (zoomer_id) {
            query += ` AND ps.zoomer_id = $2`;
            params.push(zoomer_id);
        }
        
        const schedules = await pool.query(query, params);
        
        const results = [];
        
        for (const schedule of schedules.rows) {
            try {
                const payoutResult = await executePayout(schedule);
                results.push(payoutResult);
            } catch (error) {
                results.push({
                    zoomer_id: schedule.zoomer_id,
                    status: 'failed',
                    error: error.message
                });
            }
        }
        
        res.json({
            success: true,
            payouts_executed: results.length,
            results
        });
    } catch (error) {
        console.error('Error executing payouts:', error);
        res.status(500).json({ error: 'Failed to execute payouts' });
    }
});

// Utför payout via Stripe Connect
async function executePayout(schedule) {
    const client = await pool.connect();
    
    try {
        await client.query('BEGIN');
        
        const amount_qz_token = schedule.balance_qz_token;
        const amount_usd = qzToUsd(amount_qz_token);
        
        // Skapa Stripe Transfer
        const transfer = await stripe.transfers.create({
            amount: Math.round(amount_usd * 100), // Stripe använder cent
            currency: 'usd',
            destination: schedule.stripe_connect_account_id,
            description: `quiXzoom payout for ${schedule.zoomer_name}`
        });
        
        // Skapa payout record
        const payoutResult = await client.query(
            `INSERT INTO payout_executions 
             (zoomer_id, wallet_id, amount_qz_token, amount_usd, exchange_rate, stripe_transfer_id, status, processed_at)
             VALUES ($1, $2, $3, $4, $5, $6, $7, NOW())
             RETURNING *`,
            [schedule.zoomer_id, schedule.wallet_id, amount_qz_token, amount_usd, QZ_TO_USD_RATE, transfer.id, 'completed']
        );
        
        // Skapa token transaction (burn/payout)
        const txHash = generateTxHash();
        await client.query(
            `INSERT INTO token_transactions 
             (tx_hash, tx_type, from_wallet_id, amount_qz_token, amount_usd, exchange_rate, stripe_payout_id, description, status, confirmed_at)
             VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, NOW())`,
            [txHash, 'payout', schedule.wallet_id, amount_qz_token, amount_usd, QZ_TO_USD_RATE, payoutResult.rows[0].id, `Weekly payout to ${schedule.zoomer_name}`, 'confirmed']
        );
        
        // Nollställ wallet-balans
        await client.query(
            `UPDATE zoomer_wallets SET balance_qz_token = 0 WHERE id = $1`,
            [schedule.wallet_id]
        );
        
        await client.query('COMMIT');
        
        return {
            zoomer_id: schedule.zoomer_id,
            status: 'completed',
            amount_qz_token,
            amount_usd,
            stripe_transfer_id: transfer.id
        };
    } catch (error) {
        await client.query('ROLLBACK');
        throw error;
    } finally {
        client.release();
    }
}

// ============================================================
// CUSTOMER TOP-UP
// ============================================================

// Skapa top-up (kund köper QZ TOKENS)
app.post('/api/v1/topups', async (req, res) => {
    const { customer_id, amount_usd } = req.body;
    
    try {
        const amount_qz_token = usdToQz(amount_usd);
        
        // Skapa Stripe Payment Intent
        const paymentIntent = await stripe.paymentIntents.create({
            amount: Math.round(amount_usd * 100),
            currency: 'usd',
            customer: customer_id,
            description: `quiXzoom Top-up: ${amount_qz_token} QZ TOKEN`
        });
        
        const result = await pool.query(
            `INSERT INTO customer_topups 
             (customer_id, amount_qz_token, amount_usd, exchange_rate, stripe_payment_intent_id, status)
             VALUES ($1, $2, $3, $4, $5, $6)
             RETURNING *`,
            [customer_id, amount_qz_token, amount_usd, QZ_TO_USD_RATE, paymentIntent.id, 'pending']
        );
        
        res.json({
            success: true,
            topup: result.rows[0],
            client_secret: paymentIntent.client_secret
        });
    } catch (error) {
        console.error('Error creating top-up:', error);
        res.status(500).json({ error: 'Failed to create top-up' });
    }
});

// Webhook för Stripe-händelser
app.post('/api/v1/webhooks/stripe', express.raw({ type: 'application/json' }), async (req, res) => {
    const sig = req.headers['stripe-signature'];
    
    try {
        const event = stripe.webhooks.constructEvent(req.body, sig, process.env.STRIPE_WEBHOOK_SECRET);
        
        switch (event.type) {
            case 'payment_intent.succeeded':
                await handlePaymentSuccess(event.data.object);
                break;
                
            case 'transfer.paid':
                await handleTransferPaid(event.data.object);
                break;
                
            default:
                console.log(`Unhandled event type: ${event.type}`);
        }
        
        res.json({ received: true });
    } catch (error) {
        console.error('Webhook error:', error);
        res.status(400).send(`Webhook Error: ${error.message}`);
    }
});

async function handlePaymentSuccess(paymentIntent) {
    await pool.query(
        `UPDATE customer_topups 
         SET status = 'completed', completed_at = NOW()
         WHERE stripe_payment_intent_id = $1`,
        [paymentIntent.id]
    );
}

async function handleTransferPaid(transfer) {
    await pool.query(
        `UPDATE payout_executions 
         SET status = 'completed', completed_at = NOW()
         WHERE stripe_transfer_id = $1`,
        [transfer.id]
    );
}

// ============================================================
// HEALTH CHECK
// ============================================================

app.get('/health', (req, res) => {
    res.json({ status: 'ok', service: 'qz-token-api' });
});

// Starta server
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
    console.log(`QZ Token API running on port ${PORT}`);
});

module.exports = app;