/**
 * MCP Outline PostgreSQL - PostgreSQL Client
 * @author Descomplicar® | @link descomplicar.pt | @copyright 2026
 */

import { Pool, PoolConfig, QueryResult, QueryResultRow } from 'pg';
import { DatabaseConfig } from './config/database.js';
import { logger } from './utils/logger.js';

export class PgClient {
  private pool: Pool;
  private isConnected: boolean = false;

  constructor(config: DatabaseConfig) {
    const poolConfig: PoolConfig = config.connectionString
      ? {
        connectionString: config.connectionString,
        max: config.max,
        idleTimeoutMillis: config.idleTimeoutMillis,
        connectionTimeoutMillis: config.connectionTimeoutMillis
      }
      : {
        host: config.host,
        port: config.port,
        user: config.user,
        password: config.password,
        database: config.database,
        ssl: config.ssl ? { rejectUnauthorized: false } : false,
        max: config.max,
        idleTimeoutMillis: config.idleTimeoutMillis,
        connectionTimeoutMillis: config.connectionTimeoutMillis
      };

    this.pool = new Pool(poolConfig);

    // Handle pool errors
    this.pool.on('error', (err) => {
      logger.error('Unexpected PostgreSQL pool error', { error: err.message });
    });
  }

  /**
   * Get the underlying pool for direct access
   */
  getPool(): Pool {
    return this.pool;
  }

  /**
   * Test database connection
   */
  async testConnection(): Promise<boolean> {
    let client = null;
    try {
      client = await this.pool.connect();
      await client.query('SELECT 1');
      this.isConnected = true;
      logger.info('PostgreSQL connection successful');
      return true;
    } catch (error) {
      logger.error('PostgreSQL connection failed', {
        error: error instanceof Error ? error.message : String(error)
      });
      this.isConnected = false;
      return false;
    } finally {
      if (client) {
        client.release();
      }
    }
  }

  /**
   * Execute a query with parameters
   */
  async query<T extends QueryResultRow = any>(sql: string, params?: any[]): Promise<T[]> {
    const start = Date.now();
    try {
      const result = await this.pool.query<T>(sql, params);
      const duration = Date.now() - start;

      logger.debug('Query executed', {
        sql: sql.substring(0, 100),
        duration,
        rowCount: result.rowCount
      });

      return result.rows;
    } catch (error) {
      const duration = Date.now() - start;
      logger.error('Query failed', {
        sql: sql.substring(0, 100),
        duration,
        error: error instanceof Error ? error.message : String(error)
      });
      throw error;
    }
  }

  /**
   * Execute a query and return the full result
   */
  async queryRaw<T extends QueryResultRow = any>(sql: string, params?: any[]): Promise<QueryResult<T>> {
    return this.pool.query<T>(sql, params);
  }

  /**
   * Execute a query and return a single row
   */
  async queryOne<T extends QueryResultRow = any>(sql: string, params?: any[]): Promise<T | null> {
    const rows = await this.query<T>(sql, params);
    return rows.length > 0 ? rows[0] : null;
  }

  /**
   * Execute multiple queries in a transaction
   */
  async transaction<T>(callback: (client: any) => Promise<T>): Promise<T> {
    const client = await this.pool.connect();
    try {
      await client.query('BEGIN');
      const result = await callback(client);
      await client.query('COMMIT');
      return result;
    } catch (error) {
      try {
        await client.query('ROLLBACK');
      } catch (rollbackError) {
        logger.error('Rollback failed', {
          error: rollbackError instanceof Error ? rollbackError.message : String(rollbackError),
        });
      }
      throw error;
    } finally {
      client.release();
    }
  }

  /**
   * Close the pool
   */
  async close(): Promise<void> {
    await this.pool.end();
    this.isConnected = false;
    logger.info('PostgreSQL pool closed');
  }

  /**
   * Check if connected
   */
  isPoolConnected(): boolean {
    return this.isConnected;
  }
}

// Export a singleton factory
let instance: PgClient | null = null;

export function createPgClient(config: DatabaseConfig): PgClient {
  if (!instance) {
    instance = new PgClient(config);
  }
  return instance;
}

export function getPgClient(): PgClient | null {
  return instance;
}