import { NextResponse } from 'next/server';
import supabase from '@/lib/db';

interface IPKData {
  tahun_angkatan: number;
  rata_rata_ipk: number;
}

export async function GET() {
  try {
    const { data, error } = await supabase
      .from('mahasiswa')
      .select('tahun_angkatan, ipk')
      .not('ipk', 'is', null);

    if (error) {
      console.error('Error fetching IPK data:', error);
      return NextResponse.json(
        { error: 'Failed to fetch IPK data' },
        { 
          status: 500,
          headers: {
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'GET, OPTIONS',
            'Access-Control-Allow-Headers': 'Content-Type, Authorization',
          },
        }
      );
    }

    // Kelompokkan berdasarkan tahun_angkatan dan hitung rata-rata IPK
    const groupedData = data.reduce((acc, item) => {
      const tahun = item.tahun_angkatan;
      if (!acc[tahun]) {
        acc[tahun] = { sum: 0, count: 0 };
      }
      acc[tahun].sum += item.ipk || 0;
      acc[tahun].count += 1;
      return acc;
    }, {} as Record<number, { sum: number; count: number }>);

    // Konversi ke format akhir
    const results: IPKData[] = Object.entries(groupedData).map(([tahun, data]) => ({
      tahun_angkatan: parseInt(tahun),
      rata_rata_ipk: Math.round((data.sum / data.count) * 100) / 100
    }));

    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 IPK data:', error);
    return NextResponse.json(
      { error: 'Failed to fetch IPK data' },
      { 
        status: 500,
        headers: {
          'Access-Control-Allow-Origin': '*',
          'Access-Control-Allow-Methods': 'GET, OPTIONS',
          'Access-Control-Allow-Headers': 'Content-Type, Authorization',
        },
      }
    );
  }
}