#!/usr/bin/env node

/**
 * Script zum Prüfen und Bereinigen von PostgreSQL-Verbindungen
 */

import './config/loadEnv.js';
import { sequelize } from './utils/sequelize.js';

async function main() {
    try {
        console.log('🔍 Prüfe PostgreSQL-Verbindungen...\n');
        
        // Prüfe aktive Verbindungen
        const [connections] = await sequelize.query(`
            SELECT 
                count(*) as total,
                count(*) FILTER (WHERE state = 'active') as active,
                count(*) FILTER (WHERE state = 'idle') as idle,
                count(*) FILTER (WHERE state = 'idle in transaction') as idle_in_transaction,
                count(*) FILTER (WHERE usename = current_user) as my_connections
            FROM pg_stat_activity
            WHERE datname = current_database();
        `);
        
        console.log('📊 Verbindungsstatistik:');
        console.log(`   Gesamt: ${connections[0].total}`);
        console.log(`   Aktiv: ${connections[0].active}`);
        console.log(`   Idle: ${connections[0].idle}`);
        console.log(`   Idle in Transaction: ${connections[0].idle_in_transaction}`);
        console.log(`   Meine Verbindungen: ${connections[0].my_connections}\n`);
        
        // Prüfe max_connections Limit
        const [maxConn] = await sequelize.query(`
            SELECT setting::int as max_connections 
            FROM pg_settings 
            WHERE name = 'max_connections';
        `);
        console.log(`📈 Max Connections Limit: ${maxConn[0].max_connections}`);
        console.log(`📉 Verfügbare Connections: ${maxConn[0].max_connections - connections[0].total}\n`);
        
        // Zeige alte idle Verbindungen
        const [oldConnections] = await sequelize.query(`
            SELECT 
                pid,
                usename,
                application_name,
                state,
                state_change,
                now() - state_change as idle_duration,
                query
            FROM pg_stat_activity
            WHERE datname = current_database()
            AND state = 'idle'
            AND state_change < now() - interval '1 minute'
            ORDER BY state_change ASC
            LIMIT 10;
        `);
        
        if (oldConnections.length > 0) {
            console.log(`⚠️  Gefunden ${oldConnections.length} alte idle Verbindungen (> 1 Minute):`);
            oldConnections.forEach(conn => {
                console.log(`   PID: ${conn.pid}, User: ${conn.usename}, Idle seit: ${conn.idle_duration}`);
            });
            console.log('\n💡 Tipp: Du kannst alte Verbindungen beenden mit:');
            console.log('   SELECT pg_terminate_backend(pid) FROM pg_stat_activity');
            console.log('   WHERE datname = current_database() AND state = \'idle\' AND state_change < now() - interval \'5 minutes\';\n');
        }
        
        // Prüfe ob wir nahe am Limit sind
        const usagePercent = (connections[0].total / maxConn[0].max_connections) * 100;
        if (usagePercent > 80) {
            console.log(`⚠️  WARNUNG: ${usagePercent.toFixed(1)}% der verfügbaren Verbindungen werden verwendet!`);
            console.log('   Es könnte sein, dass nicht genug Verbindungen verfügbar sind.\n');
        }
        
        await sequelize.close();
        process.exit(0);
        
    } catch (error) {
        console.error('❌ Fehler:', error.message);
        process.exit(1);
    }
}

main();