const express = require('express');
const router = express.Router();
const { exec, execSync } = require('child_process');
const db = require('../db');
const path = require('path');
const fs = require('fs');
const { isAuthenticated, hasRole } = require('../middleware/authMiddleware');
const { generateLicense, verifyLicense } = require('../utils/licenseManager');
const { checkRemoteKey } = require('../utils/remoteLicense');

// Load Public Key for Verification
const publicKeyPath = path.join(__dirname, '../config/public_key.pem');
let publicKey = null;
try {
    if (fs.existsSync(publicKeyPath)) {
        publicKey = fs.readFileSync(publicKeyPath, 'utf8');
        console.log('✅ Public Key loaded successfully for license verification');
    } else {
        console.error('❌ WARNING: public_key.pem not found at:', publicKeyPath);
    }
} catch (e) {
    console.error('❌ Error loading public key:', e);
}

// Helper to check if a setting key is allowed for general get/post
// This prevents modification of sensitive keys if any
const ALLOWED_SETTING_KEYS = [
    'subscriber_id',
    'session_timeout',
    'encryption_key',
    'asset_id_rule',
    'asset_categories',
    'asset_locations',
    'asset_statuses',
    'asset_maintenance_types'
];

// --- .env File Utilities ---
const envPath = path.join(__dirname, '../.env');

const readEnv = () => {
    if (!fs.existsSync(envPath)) return {};
    const content = fs.readFileSync(envPath, 'utf8');
    const lines = content.split('\n');
    const env = {};
    lines.forEach(line => {
        const match = line.match(/^\s*([\w.-]+)\s*=\s*(.*)?\s*$/);
        if (match) {
            env[match[1]] = match[2] ? match[2].trim() : '';
        }
    });
    return env;
};

const writeEnv = (updates) => {
    let content = fs.readFileSync(envPath, 'utf8');
    Object.entries(updates).forEach(([key, value]) => {
        const regex = new RegExp(`^${key}=.*`, 'm');
        if (regex.test(content)) {
            content = content.replace(regex, `${key}=${value}`);
        } else {
            content += `\n${key}=${value}`;
        }
    });
    fs.writeFileSync(envPath, content, 'utf8');
};

const mysql = require('mysql2/promise');

// 0. Server Configuration (Subscriber ID & Session Timeout)
router.get('/settings', isAuthenticated, hasRole('admin'), async (req, res) => {
    try {
        const [rows] = await db.query("SELECT setting_key, setting_value FROM system_settings WHERE setting_key IN ('subscriber_id', 'session_timeout', 'encryption_key')");
        const settings = {};
        rows.forEach(r => settings[r.setting_key] = r.setting_value);

        // Include .env DB settings
        const env = readEnv();

        res.json({
            subscriber_id: settings.subscriber_id || '',
            session_timeout: parseInt(settings.session_timeout) || 60,
            encryption_key: settings.encryption_key || '',
            db_config: {
                host: env.DB_HOST || '',
                user: env.DB_USER || '',
                password: env.DB_PASSWORD || '',
                database: env.DB_NAME || '',
                port: env.DB_PORT || '3306'
            }
        });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

router.post('/settings', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { subscriber_id, session_timeout, encryption_key, db_config } = req.body;

    try {
        if (subscriber_id !== undefined) {
            await db.query(`INSERT INTO system_settings (setting_key, setting_value) VALUES ('subscriber_id', ?) ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value)`, [subscriber_id]);
        }
        if (session_timeout !== undefined) {
            await db.query(`INSERT INTO system_settings (setting_key, setting_value) VALUES ('session_timeout', ?) ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value)`, [session_timeout.toString()]);
        }
        if (encryption_key !== undefined) {
            const encryptedKeyForDb = cryptoUtil.encryptMasterKey(encryption_key);
            await db.query(`INSERT INTO system_settings (setting_key, setting_value) VALUES ('encryption_key', ?) ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value)`, [encryptedKeyForDb]);
        }

        // Handle .env DB settings
        if (db_config) {
            writeEnv({
                DB_HOST: db_config.host,
                DB_USER: db_config.user,
                DB_PASSWORD: db_config.password,
                DB_NAME: db_config.database,
                DB_PORT: db_config.port
            });
        }

        res.json({ message: 'Settings saved. Server may restart to apply DB changes.' });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// --- Crypto & Key Rotation ---
const cryptoUtil = require('../utils/cryptoUtil');

// 0.2 Test DB Connection
router.post('/test-db', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { host, user, password, database, port } = req.body;

    let conn;
    try {
        conn = await mysql.createConnection({
            host,
            user,
            password,
            database,
            port: parseInt(port) || 3306,
            connectTimeout: 5000
        });
        await conn.query('SELECT 1');
        res.json({ success: true, message: '연결 성공: 데이터베이스에 성공적으로 접속되었습니다.' });
    } catch (err) {
        res.status(400).json({ success: false, error: err.message });
    } finally {
        if (conn) await conn.end();
    }
});

// 0.3 Encryption Key Management & Rotation
router.get('/encryption/status', isAuthenticated, hasRole('admin'), async (req, res) => {
    try {
        const [userRows] = await db.query('SELECT COUNT(*) as count FROM users WHERE phone IS NOT NULL AND phone LIKE "%:%"');
        const currentKey = await cryptoUtil.getMasterKey();

        res.json({
            current_key: currentKey,
            affected_records: {
                users: userRows[0].count
            }
        });
    } catch (err) {
        res.status(500).json({ error: 'Failed to fetch encryption status' });
    }
});

router.post('/encryption/rotate', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { new_key } = req.body;
    if (!new_key) return res.status(400).json({ error: 'New key is required' });

    const conn = await db.getConnection();
    try {
        await conn.beginTransaction();

        const oldKey = await cryptoUtil.getMasterKey();

        // 1. Migrate Users Table (phone)
        const [users] = await conn.query('SELECT id, phone FROM users WHERE phone IS NOT NULL AND phone LIKE "%:%"');
        for (const user of users) {
            const decrypted = await cryptoUtil.decrypt(user.phone, oldKey);
            const reEncrypted = await cryptoUtil.encrypt(decrypted, new_key);
            await conn.query('UPDATE users SET phone = ? WHERE id = ?', [reEncrypted, user.id]);
        }

        // 2. Update Master Key in settings (Encrypted for DB storage)
        const encryptedKeyForDb = cryptoUtil.encryptMasterKey(new_key);
        await conn.query(`INSERT INTO system_settings (setting_key, setting_value) VALUES ('encryption_key', ?) ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value)`, [encryptedKeyForDb]);

        await conn.commit();
        cryptoUtil.clearCache(); // Force immediate reload of new key

        res.json({ success: true, message: 'Encryption key rotated and data migrated successfully.' });
    } catch (err) {
        await conn.rollback();
        console.error('Rotation failed:', err);
        res.status(500).json({ error: 'Key rotation failed: ' + err.message });
    } finally {
        conn.release();
    }
});

// 0-1. Generic Setting Get/Set
router.get('/settings/:key', isAuthenticated, async (req, res) => {
    const { key } = req.params;
    if (!ALLOWED_SETTING_KEYS.includes(key)) {
        return res.status(400).json({ error: 'Invalid setting key' });
    }

    try {
        const [rows] = await db.query("SELECT setting_value FROM system_settings WHERE setting_key = ?", [key]);
        if (rows.length === 0) return res.json({ value: null });
        res.json({ value: rows[0].setting_value });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

router.post('/settings/:key', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { key } = req.params;
    const { value } = req.body;

    if (!ALLOWED_SETTING_KEYS.includes(key)) {
        return res.status(400).json({ error: 'Invalid setting key' });
    }

    try {
        let stringValue = typeof value === 'string' ? value : JSON.stringify(value);

        // Special handling for encryption_key to protect it in DB
        if (key === 'encryption_key') {
            stringValue = cryptoUtil.encryptMasterKey(stringValue);
        }

        await db.query(
            `INSERT INTO system_settings (setting_key, setting_value) 
             VALUES (?, ?) 
             ON DUPLICATE KEY UPDATE setting_value = VALUES(setting_value)`,
            [key, stringValue]
        );
        res.json({ success: true, message: 'Setting saved' });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// 1. Get All Modules Status
router.get('/modules', isAuthenticated, async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM system_modules');

        const modules = {};
        const defaults = ['asset', 'production', 'monitoring'];

        // Get stored subscriber ID
        const [subRows] = await db.query("SELECT setting_value FROM system_settings WHERE setting_key = 'subscriber_id'");
        const serverSubscriberId = subRows.length > 0 ? subRows[0].setting_value : null;

        defaults.forEach(code => {
            const found = rows.find(r => r.code === code);
            if (found) {
                modules[code] = {
                    active: !!found.is_active,
                    type: found.license_type,
                    expiry: found.expiry_date,
                    subscriber_id: found.subscriber_id // Return who verified it
                };
            } else {
                modules[code] = { active: false, type: null, expiry: null, subscriber_id: null };
            }
        });

        res.json({ modules, serverSubscriberId });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

const axios = require('axios');

// 2. Activate Module (Apply License)
// Only admin can manage system modules
router.post('/modules/:code/activate', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { code } = req.params;
    let { licenseKey } = req.body;

    if (!licenseKey) {
        return res.status(400).json({ error: 'License key is required' });
    }

    licenseKey = licenseKey.trim();

    // 1. Verify Key validity
    const result = verifyLicense(licenseKey, publicKey);
    if (!result.isValid) {
        return res.status(400).json({ error: `Invalid License: ${result.reason}` });
    }

    // 2. Check Module match
    if (result.module !== code) {
        return res.status(400).json({ error: `This license is for '${result.module}' module, not '${code}'` });
    }

    // 3. Check Subscriber match
    try {
        const [subRows] = await db.query("SELECT setting_value FROM system_settings WHERE setting_key = 'subscriber_id'");
        const serverSubscriberId = subRows.length > 0 ? subRows[0].setting_value : null;

        if (!serverSubscriberId) {
            return res.status(400).json({ error: '서버 구독자 ID가 설정되지 않았습니다. [서버 환경 설정]에서 먼저 설정해주세요.' });
        }

        // Allow 'dev' type to bypass strict subscriber check, but log it
        if (result.type === 'dev') {
            if (result.subscriberId !== serverSubscriberId) {
                console.warn(`⚠️ Dev License used: Subscriber ID mismatch allowed. Key: ${result.subscriberId}, Server: ${serverSubscriberId}`);
            }
        } else {
            if (result.subscriberId !== serverSubscriberId) {
                return res.status(403).json({
                    error: `구독자 ID 불일치: 라이선스 키는 [${result.subscriberId}] 전용이지만, 현재 서버는 [${serverSubscriberId}]로 설정되어 있습니다.`
                });
            }
        }

        // 4. Archive Current License if exists
        const [current] = await db.query('SELECT * FROM system_modules WHERE code = ?', [code]);
        if (current.length > 0 && current[0].is_active && current[0].license_key) {
            const old = current[0];
            const historySql = `
                    INSERT INTO license_history (module_code, license_key, license_type, subscriber_id, activated_at)
                    VALUES (?, ?, ?, ?, NOW())
                `;
            await db.query(historySql, [old.code, old.license_key, old.license_type, old.subscriber_id]);
        }

        // Upsert into system_modules
        const sql = `
            INSERT INTO system_modules (code, name, is_active, license_key, license_type, expiry_date, subscriber_id)
            VALUES (?, ?, true, ?, ?, ?, ?)
            ON DUPLICATE KEY UPDATE
            is_active = true,
            license_key = VALUES(license_key),
            license_type = VALUES(license_type),
            expiry_date = VALUES(expiry_date),
            subscriber_id = VALUES(subscriber_id)
        `;

        // Map codes to names
        const names = {
            'asset': '자산 관리',
            'production': '생산 관리',
            'monitoring': 'CCTV'
        };

        await db.query(sql, [code, names[code] || code, licenseKey, result.type, result.expiryDate, result.subscriberId]);

        // 5. Sync status with License Manager
        const licenseManagerUrl = process.env.LICENSE_MANAGER_URL || 'http://localhost:3006/api';
        try {
            await axios.post(`${licenseManagerUrl}/licenses/activate`, { licenseKey });
            console.log(`✅ Synced activation status for key: ${licenseKey.substring(0, 20)}...`);
        } catch (syncErr) {
            const errorDetail = syncErr.response ?
                `Status: ${syncErr.response.status}, Data: ${JSON.stringify(syncErr.response.data)}` :
                syncErr.message;
            console.error(`⚠️ Failed to sync status with License Manager: ${errorDetail}`);
            // We don't fail the whole activation if sync fails, but we log it
        }

        res.json({ success: true, message: 'Module activated', type: result.type, expiry: result.expiryDate });

    } catch (err) {
        console.error('❌ License Activation Error:', err);
        res.status(500).json({
            success: false,
            error: err.message || 'Database error',
            stack: process.env.NODE_ENV === 'development' ? err.stack : undefined
        });
    }
});

// 3. Get Module History
router.get('/modules/:code/history', isAuthenticated, hasRole('admin'), async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM license_history WHERE module_code = ? ORDER BY id DESC LIMIT 10', [req.params.code]);
        res.json(rows);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// 4. Deactivate Module
router.post('/modules/:code/deactivate', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { code } = req.params;
    try {
        // Archive on deactivate too?
        const [current] = await db.query('SELECT * FROM system_modules WHERE code = ?', [code]);
        if (current.length > 0 && current[0].is_active) {
            const old = current[0];
            const historySql = `
                INSERT INTO license_history (module_code, license_key, license_type, subscriber_id, activated_at)
                VALUES (?, ?, ?, ?, NOW())
            `;
            await db.query(historySql, [old.code, old.license_key, old.license_type, old.subscriber_id]);
        }

        await db.query('UPDATE system_modules SET is_active = false WHERE code = ?', [code]);
        res.json({ success: true, message: 'Module deactivated' });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});



// --- System Update Logic ---

// 5. Get Version Info (Current & Remote)
router.get('/version/remote', isAuthenticated, hasRole('admin'), async (req, res) => {
    try {
        const packageJsonPath = path.join(__dirname, '../package.json');
        const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
        const currentVersion = packageJson.version;

        // Run git fetch to update tags from remote
        exec('git fetch --tags', (err) => {
            if (err) {
                console.error('Git fetch failed:', err);
                return res.json({
                    current: currentVersion,
                    latest: null,
                    error: '원격 저장소에 연결할 수 없습니다. Git 설정을 확인하세요.'
                });
            }

            // Get the latest tag
            exec('git describe --tags $(git rev-list --tags --max-count=1)', (err, stdout) => {
                const latestTag = stdout ? stdout.trim() : null;
                res.json({
                    current: currentVersion,
                    latest: latestTag,
                    needsUpdate: latestTag ? (latestTag.replace(/^v/, '') !== currentVersion.replace(/^v/, '')) : false
                });
            });
        });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: '버전 정보를 가져오는 중 오류가 발생했습니다.' });
    }
});

// 6. Execute System Update
// WARNING: This is a heavy operation and will reload the server
router.post('/version/update', isAuthenticated, hasRole('admin'), async (req, res) => {
    const { targetTag } = req.body;

    if (!targetTag) {
        return res.status(400).json({ error: '업데이트할 대상 태그가 지정되지 않았습니다.' });
    }

    // This operation is asynchronous. We start it and return a message.
    // In a real production, we might want to log this to a terminal-like view.

    const updateScript = `
        git checkout ${targetTag} && 
        npm install && 
        npm run build && 
        cd server && 
        npm install && 
        pm2 reload smartims-api
    `;

    // Note: On Windows, we might need a different script or use a shell
    const isWindows = process.platform === 'win32';
    const shellCommand = isWindows ? `powershell.exe -Command "${updateScript.replace(/\n/g, '')}"` : updateScript;

    console.log(`🚀 Starting system update to ${targetTag}...`);

    exec(shellCommand, { cwd: path.join(__dirname, '../..') }, (err, stdout, stderr) => {
        if (err) {
            console.error('❌ Update Failed:', err);
            console.error(stderr);
            return;
        }
        console.log('✅ Update completed successfully.');
        console.log(stdout);
    });

    res.json({
        success: true,
        message: '업데이트 프로세스가 백그라운드에서 시작되었습니다. 약 1~3분 후 시스템이 재시작됩니다.'
    });
});

module.exports = router;