import { QueryResult } from '../types';
import { databasePoolManager } from './DatabasePoolManager';

export class SqlExecutor {
  private async retryQuery<T>(
    fn: () => Promise<T>,
    retries: number = 3,
    delay: number = 1000
  ): Promise<T> {
    for (let attempt = 1; attempt <= retries; attempt++) {
      try {
        return await fn();
      } catch (error: any) {
        // Retry only on connection-related errors
        const isConnectionError =
          error.message?.includes('timeout') ||
          error.message?.includes('Connection terminated') ||
          error.message?.includes('ECONNREFUSED') ||
          error.message?.includes('ETIMEDOUT');

        if (!isConnectionError || attempt === retries) {
          throw error;
        }

        console.warn(`Query attempt ${attempt} failed, retrying in ${delay}ms...`);
        await new Promise(resolve => setTimeout(resolve, delay));
      }
    }
    throw new Error('Max retries exceeded');
  }

  async executeQuery(
    databaseId: string,
    sqlQuery: string,
    params: any[] = []
  ): Promise<QueryResult> {
    const pool = databasePoolManager.getPool(databaseId);

    if (!pool) {
      throw new Error(`Database with id ${databaseId} not found or not configured`);
    }

    const startTime = Date.now();

    try {
      // Security: Prevent multiple statements and dangerous commands
      this.validateQuery(sqlQuery);

      // Execute with retry mechanism
      const result = await this.retryQuery(async () => {
        return await pool.query(sqlQuery, params);
      }, 3, 500); // 3 попытки с задержкой 500ms

      const executionTime = Date.now() - startTime;

      return {
        rows: result.rows,
        rowCount: result.rowCount || 0,
        executionTime,
      };
    } catch (error: any) {
      console.error('SQL Execution Error:', error);
      throw new Error(`SQL Error: ${error.message}`);
    }
  }

  private validateQuery(sqlQuery: string) {
    const normalized = sqlQuery.trim().toLowerCase();

    // Prevent multiple statements (basic check)
    if (normalized.includes(';') && normalized.indexOf(';') < normalized.length - 1) {
      throw new Error('Multiple SQL statements are not allowed');
    }

    // Prevent dangerous commands (you can extend this list)
    const dangerousCommands = ['drop', 'truncate', 'delete from', 'alter', 'create', 'grant', 'revoke'];
    const isDangerous = dangerousCommands.some(cmd => normalized.startsWith(cmd));

    if (isDangerous && !normalized.startsWith('select')) {
      // For safety, you might want to allow only SELECT queries
      // Or implement a whitelist/permission system for write operations
      console.warn('Potentially dangerous query detected:', sqlQuery);
    }
  }

  async testQuery(databaseId: string, sqlQuery: string): Promise<{ success: boolean; error?: string }> {
    try {
      await this.executeQuery(databaseId, sqlQuery);
      return { success: true };
    } catch (error: any) {
      return { success: false, error: error.message };
    }
  }

  async getTableSchema(databaseId: string, tableName: string): Promise<any[]> {
    const query = `
      SELECT
        column_name,
        data_type,
        is_nullable,
        column_default
      FROM
        information_schema.columns
      WHERE
        table_name = $1
      ORDER BY
        ordinal_position;
    `;

    const result = await this.executeQuery(databaseId, query, [tableName]);
    return result.rows;
  }

  async getAllTables(databaseId: string): Promise<string[]> {
    const query = `
      SELECT table_name
      FROM information_schema.tables
      WHERE table_schema = 'public'
      ORDER BY table_name;
    `;

    const result = await this.executeQuery(databaseId, query);
    return result.rows.map(row => row.table_name);
  }
}

export const sqlExecutor = new SqlExecutor();