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

export async function GET() {
  try {
    const currentYear = new Date().getFullYear();
    const { data, error } = await supabase
      .from('mahasiswa')
      .select('tahun_angkatan')
      .gte('tahun_angkatan', currentYear - 10)
      .order('tahun_angkatan', { ascending: false });

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

    // Get unique tahun_angkatan values and limit to 7 most recent
    const uniqueYears = [...new Set(data.map(item => item.tahun_angkatan))]
      .sort((a, b) => b - a) // Sort descending
      .slice(0, 7); // Take only 7 most recent years

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