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 year = parseInt(searchParams.get('year') || String(new Date().getFullYear()), 10);

  try {
    const monthlyRows = await query(
      'SELECT' +
      '  MONTH(Beginn) AS monat,' +
      "  COUNT(CASE WHEN ArtFuehrung IN ('RF','SF','SonF','PrF') THEN 1 END) AS tageFuehrungen," +
      "  COUNT(CASE WHEN ArtFuehrung = 'Beob' THEN 1 END) AS tageBeob," +
      "  COUNT(CASE WHEN ArtFuehrung = 'TD'    THEN 1 END) AS tageTD," +
      "  COUNT(CASE WHEN ArtFuehrung = 'Sonst' THEN 1 END) AS tageSonst," +
      "  COUNT(CASE WHEN ArtFuehrung = 'BEOS'  THEN 1 END) AS tageBEOS," +
      "  COUNT(CASE WHEN ArtFuehrung = 'ToT'   THEN 1 END) AS tagesToT," +
      "  COUNT(CASE WHEN ArtFuehrung IN ('RF','SF','SonF','PrF','Beob','TD','Sonst','BEOS','ToT') THEN 1 END) AS tageGesamt," +
      "  SUM(CASE WHEN ArtFuehrung = 'RF'   THEN Besucher ELSE 0 END) AS besucherRF," +
      "  SUM(CASE WHEN ArtFuehrung = 'SF'   THEN Besucher ELSE 0 END) AS besucherSF," +
      "  SUM(CASE WHEN ArtFuehrung = 'SonF' THEN Besucher ELSE 0 END) AS besucherSonF," +
      "  SUM(CASE WHEN ArtFuehrung = 'PrF'  THEN Besucher ELSE 0 END) AS besucherPrF," +
      "  SUM(CASE WHEN ArtFuehrung = 'ToT'  THEN Besucher ELSE 0 END) AS besucherToT," +
      "  SUM(CASE WHEN ArtFuehrung IN ('RF','SF','SonF','PrF','ToT') THEN Besucher ELSE 0 END) AS besucherGesamt" +
      ' FROM logbuch' +
      ' WHERE YEAR(Beginn) = ?' +
      ' GROUP BY MONTH(Beginn)' +
      ' ORDER BY monat',
      [year]
    ) as {
      monat: number;
      tageFuehrungen: number; tageBeob: number; tageTD: number; tageSonst: number; tageBEOS: number; tagesToT: number; tageGesamt: number;
      besucherRF: number; besucherSF: number; besucherSonF: number; besucherPrF: number;
      besucherToT: number; besucherGesamt: number;
    }[];

    const cumulativeRows = await query(
      "SELECT SUM(CASE WHEN ArtFuehrung IN ('RF','SF','SonF','PrF','ToT') THEN Besucher ELSE 0 END) AS total" +
      ' FROM logbuch WHERE YEAR(Beginn) = ?',
      [year]
    ) as { total: number | null }[];

    const tageRows = await query(
      "SELECT COUNT(*) AS tage FROM logbuch WHERE YEAR(Beginn) = ? AND ArtFuehrung IN ('RF','SF','SonF','PrF','Beob','TD','Sonst','BEOS','ToT')",
      [year]
    ) as { tage: number }[];

    return NextResponse.json({
      monthly: monthlyRows.map((r) => ({
        monat: Number(r.monat),
        tageFuehrungen: Number(r.tageFuehrungen),
        tageBeob: Number(r.tageBeob),
        tageTD: Number(r.tageTD),
        tageSonst: Number(r.tageSonst),
        tageBEOS: Number(r.tageBEOS),
        tagesToT: Number(r.tagesToT),
        tageGesamt: Number(r.tageGesamt),
        besucherRF: Number(r.besucherRF),
        besucherSF: Number(r.besucherSF),
        besucherSonF: Number(r.besucherSonF),
        besucherPrF: Number(r.besucherPrF),
        besucherToT: Number(r.besucherToT),
        besucherGesamt: Number(r.besucherGesamt),
      })),
      cumulative: Number(cumulativeRows[0]?.total ?? 0),
      tage: Number(tageRows[0]?.tage ?? 0),
      year,
    });
  } catch (error) {
    console.error('GET /api/statistik:', error);
    return NextResponse.json({ error: 'Datenbankfehler' }, { status: 500 });
  }
}