const mysql = require('mysql2/promise');
require('dotenv').config();

// Configuration for the "Vendor/Central" License Database
const remoteConfig = {
    host: process.env.LICENSE_DB_HOST,
    user: process.env.LICENSE_DB_USER,
    password: process.env.LICENSE_DB_PASSWORD,
    database: process.env.LICENSE_DB_NAME,
    port: process.env.LICENSE_DB_PORT || 3306,
    connectTimeout: 5000 // 5 seconds timeout
};

function isRemoteConfigured() {
    return !!(process.env.LICENSE_DB_HOST && process.env.LICENSE_DB_USER && process.env.LICENSE_DB_NAME);
}

/**
 * Connects to the Remote DB, checks if the key exists, and disconnects.
 * @param {string} key 
 * @returns {Promise<boolean>} valid
 */
async function checkRemoteKey(key) {
    if (!isRemoteConfigured()) {
        console.warn('⚠️ Remote License DB not configured. Skipping remote check.');
        return true; // Use local check only if remote is not configured
    }

    let conn;
    try {
        conn = await mysql.createConnection(remoteConfig);
        const [rows] = await conn.execute('SELECT 1 FROM issued_licenses WHERE license_key = ? LIMIT 1', [key]);
        return rows.length > 0;
    } catch (err) {
        console.error('❌ Remote License Check Failed:', err.message);
        return false; // Fail safe: if we can't verify remotely, assume invalid (or valid? User wanted "management", so fail is safer)
    } finally {
        if (conn) await conn.end();
    }
}

/**
 * Connects to Remote DB, inserts the generated key, and disconnects.
 * @param {object} licenseData { key, module, type }
 * @returns {Promise<void>}
 */
async function registerRemoteKey({ key, module, type }) {
    if (!isRemoteConfigured()) {
        console.log('ℹ️ Remote License DB not configured. Key generated locally only.');
        return;
    }

    let conn;
    try {
        conn = await mysql.createConnection(remoteConfig);
        const sql = `
            INSERT INTO issued_licenses (license_key, module_code, license_type, created_at)
            VALUES (?, ?, ?, NOW())
        `;
        await conn.execute(sql, [key, module, type]);
        console.log('✅ License Key registered to Central DB.');
    } catch (err) {
        console.error('❌ Failed to register key to Central DB:', err.message);
        console.warn('⚠️ The key was generated but may not be activatable if the server enforces remote check.');
    } finally {
        if (conn) await conn.end();
    }
}

module.exports = { checkRemoteKey, registerRemoteKey };