api_builder/backend/src/services/DatabasePoolManager.ts

import { Pool } from 'pg';
import { DatabaseConfig } from '../types';
import { mainPool } from '../config/database';

class DatabasePoolManager {
  private pools: Map<string, Pool> = new Map();

  async initialize() {
    // Load databases from DB instead of env
    await this.loadDatabasesFromDB();
  }

  private async loadDatabasesFromDB() {
    try {
      const result = await mainPool.query(
        'SELECT * FROM databases WHERE is_active = true'
      );

      for (const row of result.rows) {
        const dbConfig: DatabaseConfig = {
          id: row.id,
          name: row.name,
          type: row.type,
          host: row.host,
          port: row.port,
          database_name: row.database_name,
          username: row.username,
          password: row.password,
          ssl: row.ssl,
          is_active: row.is_active,
        };

        this.addPool(dbConfig);
      }

      console.log(`✅ Loaded ${result.rows.length} database connection(s) from DB`);
    } catch (error) {
      console.error('❌ Failed to load databases from DB:', error);
    }
  }

  addPool(dbConfig: DatabaseConfig) {
    if (this.pools.has(dbConfig.id)) {
      console.warn(`Pool with id ${dbConfig.id} already exists. Skipping.`);
      return;
    }

    const pool = new Pool({
      host: dbConfig.host,
      port: dbConfig.port,
      database: dbConfig.database_name,
      user: dbConfig.username,
      password: dbConfig.password,
      ssl: dbConfig.ssl ? { rejectUnauthorized: false } : false,
      max: 20, // Увеличено количество соединений
      idleTimeoutMillis: 60000, // 60 секунд
      connectionTimeoutMillis: 10000, // 10 секунд (было 2 секунды)
      keepAlive: true, // Поддерживать соединения активными
      keepAliveInitialDelayMillis: 10000, // Начать keepAlive через 10 секунд
    });

    pool.on('error', (err) => {
      console.error(`Database pool error for ${dbConfig.id}:`, err);
    });

    this.pools.set(dbConfig.id, pool);
    console.log(`✅ Pool created for database: ${dbConfig.name} (${dbConfig.id})`);
  }

  removePool(databaseId: string) {
    const pool = this.pools.get(databaseId);
    if (pool) {
      pool.end();
      this.pools.delete(databaseId);
      console.log(`Pool removed for database: ${databaseId}`);
    }
  }

  getPool(databaseId: string): Pool | undefined {
    return this.pools.get(databaseId);
  }

  async getDatabaseConfig(databaseId: string): Promise<DatabaseConfig | null> {
    try {
      const result = await mainPool.query(
        'SELECT * FROM databases WHERE id = $1',
        [databaseId]
      );
      if (result.rows.length === 0) {
        return null;
      }
      const row = result.rows[0];
      return {
        id: row.id,
        name: row.name,
        type: row.type,
        host: row.host,
        port: row.port,
        database_name: row.database_name,
        username: row.username,
        password: row.password,
        ssl: row.ssl,
        is_active: row.is_active,
        aql_base_url: row.aql_base_url,
        aql_auth_type: row.aql_auth_type,
        aql_auth_value: row.aql_auth_value,
        aql_headers: row.aql_headers,
      };
    } catch (error) {
      console.error('Error fetching database config:', error);
      return null;
    }
  }

  async getAllDatabaseConfigs(): Promise<DatabaseConfig[]> {
    try {
      const result = await mainPool.query(
        'SELECT id, name, type, host, port, database_name, is_active FROM databases WHERE is_active = true'
      );
      return result.rows;
    } catch (error) {
      console.error('Error fetching databases:', error);
      return [];
    }
  }

  async testConnection(databaseId: string): Promise<boolean> {
    const pool = this.getPool(databaseId);
    if (!pool) {
      return false;
    }

    try {
      const client = await pool.connect();
      client.release();
      return true;
    } catch (error) {
      console.error(`Connection test failed for ${databaseId}:`, error);
      return false;
    }
  }

  async reloadPool(databaseId: string) {
    // Remove old pool
    this.removePool(databaseId);

    // Load new config from DB
    const result = await mainPool.query(
      'SELECT * FROM databases WHERE id = $1 AND is_active = true',
      [databaseId]
    );

    if (result.rows.length > 0) {
      const row = result.rows[0];
      const dbConfig: DatabaseConfig = {
        id: row.id,
        name: row.name,
        type: row.type,
        host: row.host,
        port: row.port,
        database_name: row.database_name,
        username: row.username,
        password: row.password,
        ssl: row.ssl,
        is_active: row.is_active,
      };

      this.addPool(dbConfig);
    }
  }

  async closeAll() {
    const promises = Array.from(this.pools.values()).map((pool) => pool.end());
    await Promise.all(promises);
    this.pools.clear();
    console.log('All database pools closed');
  }
}

export const databasePoolManager = new DatabasePoolManager();