import { NextResponse } from 'next/server';
import pool from '@/lib/db';
import { RowDataPacket } from 'mysql2';

interface MahasiswaStatistik extends RowDataPacket {
  tahun_angkatan: number;
  total_mahasiswa: number;
  pria: number;
  wanita: number;
}

// Fungsi untuk menangani preflight request (OPTIONS)
export async function OPTIONS() {
  return new NextResponse(null, {
    status: 200,
    headers: {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'GET, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type, Authorization',
      'Access-Control-Max-Age': '86400', // 24 jam
    },
  });
}

export async function GET() {
  const connection = await pool.getConnection();
  
  try {
    // Query untuk mendapatkan statistik mahasiswa per tahun angkatan
    const [results] = await connection.query<MahasiswaStatistik[]>(`
      SELECT 
        tahun_angkatan,
        COUNT(*) as total_mahasiswa,
        SUM(CASE WHEN jk = 'Pria' THEN 1 ELSE 0 END) as pria,
        SUM(CASE WHEN jk = 'Wanita' THEN 1 ELSE 0 END) as wanita
      FROM mahasiswa
      GROUP BY tahun_angkatan
    `);

    // Menambahkan header cache dan CORS
    return NextResponse.json(results, {
      headers: {
        'Cache-Control': 'public, max-age=60, stale-while-revalidate=30',
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'GET, OPTIONS',
        'Access-Control-Allow-Headers': 'Content-Type, Authorization',
      },
    });
  } catch (error) {
    console.error('Error fetching mahasiswa statistik:', error);
    return NextResponse.json(
      { error: 'Failed to fetch mahasiswa statistik' },
      { 
        status: 500,
        headers: {
          'Access-Control-Allow-Origin': '*',
          'Access-Control-Allow-Methods': 'GET, OPTIONS',
          'Access-Control-Allow-Headers': 'Content-Type, Authorization',
        },
      }
    );
  } finally {
    connection.release();
  }
}