import { NextRequest, NextResponse } from 'next/server';
import { query } from '@/lib/db';
import { getSession } from '@/lib/session';

export async function GET(request: NextRequest) {
  const session = await getSession();
  if (!session) return NextResponse.json({ error: 'Nicht angemeldet' }, { status: 401 });

  const { searchParams } = new URL(request.url);
  const kuppel = searchParams.get('kuppel') || 'West';
  const year = parseInt(searchParams.get('year') || String(new Date().getFullYear()), 10);

  try {
    // 1) Monatliche Besucherzahlen nach ArtFuehrung
    const monthlyRows = await query(
      `SELECT
         MONTH(Beginn) AS monat,
         ArtFuehrung,
         SUM(Besucher) AS besucher,
         COUNT(*) AS anzahl
       FROM logbuch
       WHERE Kuppel = ? AND YEAR(Beginn) = ?
       GROUP BY MONTH(Beginn), ArtFuehrung
       ORDER BY monat, ArtFuehrung`,
      [kuppel, year]
    ) as { monat: number; ArtFuehrung: string; besucher: number; anzahl: number }[];

    // 2) Kumulierte Besucher im Jahr
    const cumulativeRows = await query(
      `SELECT SUM(Besucher) AS total FROM logbuch WHERE Kuppel = ? AND YEAR(Beginn) = ?`,
      [kuppel, year]
    ) as { total: number | null }[];

    // 3) Anzahl Führungstage (distinct Datum)
    const tageRows = await query(
      `SELECT COUNT(DISTINCT DATE(Beginn)) AS tage FROM logbuch WHERE Kuppel = ? AND YEAR(Beginn) = ?`,
      [kuppel, year]
    ) as { tage: number }[];

    // 4) Kumulierte Besucher über alle Kuppeln
    const allCumulativeRows = await query(
      `SELECT SUM(Besucher) AS total FROM logbuch WHERE YEAR(Beginn) = ?`,
      [year]
    ) as { total: number | null }[];

    // 5) Führungstage über alle Kuppeln
    const allTageRows = await query(
      `SELECT COUNT(DISTINCT DATE(Beginn)) AS tage FROM logbuch WHERE YEAR(Beginn) = ?`,
      [year]
    ) as { tage: number }[];

    return NextResponse.json({
      monthly: monthlyRows.map((r) => ({
        monat: Number(r.monat),
        ArtFuehrung: r.ArtFuehrung,
        besucher: Number(r.besucher),
        anzahl: Number(r.anzahl),
      })),
      cumulative: Number(cumulativeRows[0]?.total ?? 0),
      tage: Number(tageRows[0]?.tage ?? 0),
      allCumulative: Number(allCumulativeRows[0]?.total ?? 0),
      allTage: Number(allTageRows[0]?.tage ?? 0),
      year,
      kuppel,
    });
  } catch (error) {
    console.error('GET /api/statistik:', error);
    return NextResponse.json({ error: 'Datenbankfehler' }, { status: 500 });
  }
}