import { NextRequest, NextResponse } from 'next/server';
import { Pool } from 'pg';

export default async function handler(req: NextRequest) {
  if (req.method !== 'GET') {
    return new NextResponse(JSON.stringify({ error: 'Method not allowed' }), {
      status: 405,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  // Check environment variables first
  if (!process.env.DATABASE_URL) {
    return new NextResponse(JSON.stringify({
      success: false,
      error: 'DATABASE_URL environment variable not set',
      environment: process.env.NODE_ENV || 'unknown'
    }), {
      status: 500,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  const pool = new Pool({
    connectionString: process.env.DATABASE_URL,
    ssl: process.env.NODE_ENV === 'production' ? { rejectUnauthorized: false } : false,
    connectionTimeoutMillis: 10000, // 10 seconds
    query_timeout: 10000, // 10 seconds
  });

  let client: any;
  
  try {
    console.log('Testing database connection...');
    
    // Set a timeout for the entire operation
    const timeoutPromise = new Promise((_, reject) => {
      setTimeout(() => reject(new Error('Database operation timed out')), 15000);
    });

    const dbOperation = async () => {
      client = await pool.connect();
      
      // Test basic connection
      const result = await client.query('SELECT NOW() as current_time, version() as postgres_version');
      
      // Check if users table exists
      const tableCheck = await client.query(`
        SELECT EXISTS (
          SELECT FROM information_schema.tables 
          WHERE table_schema = 'public' 
          AND table_name = 'users'
        ) as users_table_exists;
      `);

      // Check if cards table exists
      const cardsCheck = await client.query(`
        SELECT EXISTS (
          SELECT FROM information_schema.tables 
          WHERE table_schema = 'public' 
          AND table_name = 'cards'
        ) as cards_table_exists;
      `);

      return {
        current_time: result.rows[0].current_time,
        postgres_version: result.rows[0].postgres_version,
        users_table_exists: tableCheck.rows[0].users_table_exists,
        cards_table_exists: cardsCheck.rows[0].cards_table_exists
      };
    };

    const dbResult = await Promise.race([dbOperation(), timeoutPromise]);

    return new NextResponse(JSON.stringify({
      success: true,
      message: 'Database connection successful',
      database_info: dbResult
    }), {
      status: 200,
      headers: { 'Content-Type': 'application/json' },
    });

  } catch (error) {
    console.error('Database connection failed:', error);
    return new NextResponse(JSON.stringify({ 
      success: false,
      error: 'Database connection failed',
      details: (error as Error).message,
      database_url_exists: !!process.env.DATABASE_URL,
      database_url_preview: process.env.DATABASE_URL ? 
        process.env.DATABASE_URL.substring(0, 20) + '...' : 'not set'
    }), {
      status: 500,
      headers: { 'Content-Type': 'application/json' },
    });
  } finally {
    if (client) {
      try {
        client.release();
      } catch (e) {
        console.error('Error releasing client:', e);
      }
    }
    try {
      await pool.end();
    } catch (e) {
      console.error('Error ending pool:', e);
    }
  }
}