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

// GET - Fetch all mahasiswa or a specific one by NIM
export async function GET(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const nim = searchParams.get('nim');

    if (nim) {
      // Fetch specific mahasiswa by NIM with joins
      const { data, error } = await supabase
        .from('mahasiswa')
        .select(`
          *,
          kelompok_keahlian!id_kelompok_keahlian(id_kk, nama_kelompok)
        `)
        .eq('nim', nim)
        .single();

      if (error || !data) {
        return NextResponse.json({ message: 'Mahasiswa not found' }, { status: 404 });
      }

      // Transform the data to flatten the joined fields
      const transformedData = {
        ...data,
        nama_kelompok_keahlian: data.kelompok_keahlian?.nama_kelompok || null
      };
      delete transformedData.kelompok_keahlian;

      return NextResponse.json(transformedData);
    } else {
      // Fetch all mahasiswa with joins
      const { data, error } = await supabase
        .from('mahasiswa')
        .select(`
          *,
          kelompok_keahlian!id_kelompok_keahlian(id_kk, nama_kelompok)
        `)
        .order('nim');

      if (error) {
        console.error('Error fetching data:', error);
        return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
      }

      // Transform the data to flatten the joined fields
      const transformedData = data.map(item => ({
        ...item,
        nama_kelompok_keahlian: item.kelompok_keahlian?.nama_kelompok || null
      })).map(({ kelompok_keahlian, ...rest }) => rest);

      return NextResponse.json(transformedData);
    }
  } catch (error) {
    console.error('Error fetching data:', error);
    return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
  }
}

// POST - Create a new mahasiswa
export async function POST(request: NextRequest) {
  try {
    const body = await request.json();
    const {
      nim,
      nama,
      jk,
      agama,
      kabupaten,
      provinsi,
      jenis_pendaftaran,
      tahun_angkatan,
      ipk,
      id_kelompok_keahlian,
      status_kuliah,
      semester
    } = body;

    // Validate required fields
    if (!nim || !nama || !jk || !tahun_angkatan) {
      return NextResponse.json(
        { message: 'Missing required fields: nim, nama, jk, tahun_angkatan' },
        { status: 400 }
      );
    }

    // Check if mahasiswa already exists
    const { data: existing, error: checkError } = await supabase
      .from('mahasiswa')
      .select('nim')
      .eq('nim', nim)
      .single();

    if (existing) {
      return NextResponse.json(
        { message: 'Mahasiswa with this NIM already exists' },
        { status: 409 }
      );
    }

    // Insert new mahasiswa
    const { data, error } = await supabase
      .from('mahasiswa')
      .insert({
        nim,
        nama,
        jk,
        agama: agama || null,
        kabupaten: kabupaten || null,
        provinsi: provinsi || null,
        jenis_pendaftaran: jenis_pendaftaran || null,
        tahun_angkatan,
        ipk: ipk || null,
        id_kelompok_keahlian: id_kelompok_keahlian || null,
        status_kuliah: status_kuliah || "Aktif",
        semester: semester || 1
      })
      .select()
      .single();

    if (error) {
      console.error('Error creating mahasiswa:', error);
      return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
    }

    return NextResponse.json(
      { message: 'Mahasiswa created successfully', nim },
      { status: 201 }
    );
  } catch (error) {
    console.error('Error creating mahasiswa:', error);
    return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
  }
}

// PUT - Update an existing mahasiswa
export async function PUT(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const nim = searchParams.get('nim');

    if (!nim) {
      return NextResponse.json({ message: 'NIM is required' }, { status: 400 });
    }

    const body = await request.json();
    const {
      nama,
      jk,
      agama,
      kabupaten,
      provinsi,
      jenis_pendaftaran,
      tahun_angkatan,
      ipk,
      id_kelompok_keahlian,
      status_kuliah,
      semester
    } = body;

    // Check if mahasiswa exists
    const { data: existing, error: checkError } = await supabase
      .from('mahasiswa')
      .select('*')
      .eq('nim', nim)
      .single();

    if (checkError || !existing) {
      return NextResponse.json({ message: 'Mahasiswa not found' }, { status: 404 });
    }

    // Update mahasiswa
    const { error } = await supabase
      .from('mahasiswa')
      .update({
        nama: nama || existing.nama,
        jk: jk || existing.jk,
        agama: agama || existing.agama,
        kabupaten: kabupaten || existing.kabupaten,
        provinsi: provinsi || existing.provinsi,
        jenis_pendaftaran: jenis_pendaftaran || existing.jenis_pendaftaran,
        tahun_angkatan: tahun_angkatan || existing.tahun_angkatan,
        ipk: ipk || existing.ipk,
        id_kelompok_keahlian: id_kelompok_keahlian || existing.id_kelompok_keahlian,
        status_kuliah: status_kuliah || existing.status_kuliah,
        semester: semester || existing.semester
      })
      .eq('nim', nim);

    if (error) {
      console.error('Error updating mahasiswa:', error);
      return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
    }

    return NextResponse.json({ message: 'Mahasiswa updated successfully', nim });
  } catch (error) {
    console.error('Error updating mahasiswa:', error);
    return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
  }
}

// DELETE - Delete a mahasiswa
export async function DELETE(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const nim = searchParams.get('nim');

    if (!nim) {
      return NextResponse.json({ message: 'NIM is required' }, { status: 400 });
    }

    // Check if mahasiswa exists
    const { data: existing, error: checkError } = await supabase
      .from('mahasiswa')
      .select('nim')
      .eq('nim', nim)
      .single();

    if (checkError || !existing) {
      return NextResponse.json({ message: 'Mahasiswa not found' }, { status: 404 });
    }

    // Delete mahasiswa
    const { error } = await supabase
      .from('mahasiswa')
      .delete()
      .eq('nim', nim);

    if (error) {
      console.error('Error deleting mahasiswa:', error);
      return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
    }

    return NextResponse.json({ message: 'Mahasiswa deleted successfully' });
  } catch (error) {
    console.error('Error deleting mahasiswa:', error);
    return NextResponse.json({ message: 'Internal Server Error' }, { status: 500 });
  }
}