/**
 * Dashboard (plan.md Abschnitt 14).
 *
 * User: sieht genau seinen einen Kalender als Karte (oeffnet die
 * Kalenderuebersicht im Modal). Reservieren ja, verwalten nein.
 * Admin: sieht alle Kalender als Karten; Klick oeffnet die
 * Kalenderuebersicht, der Stift die Verwaltung (Einstellungen,
 * Mitglieder, Regeln). Nur Admins erstellen/bearbeiten Kalender.
 */
import { redirect } from 'next/navigation';
import { prisma } from '@/lib/db/client';
import { requireDbUser } from '@/lib/api/context';
import { Card } from '@/components/ui/ui';
import { AppShell } from '@/components/layout/AppShell';
import { DashboardCalendarGrid } from '@/components/dashboard/DashboardCalendarGrid';
import type { ManagedCalendar } from '@/components/admin/CalendarManager';

export default async function DashboardPage() {
  const user = await requireDbUser().catch(() => null);
  if (!user) {
    redirect('/login');
  }

  const membership = await prisma.calendarMember.findUnique({
    where: { userId: user.id },
    select: {
      calendar: {
        select: {
          id: true,
          title: true,
          description: true,
          timezone: true,
          isActive: true,
          maxReservationMinutes: true,
          showTitleToMembers: true,
          showNotesToMembers: true,
          owner: { select: { email: true, username: true } },
          _count: { select: { members: true, reservations: true } },
        },
      },
    },
  });

  const ownedCalendars =
    user.role === 'ADMIN'
      ? await prisma.calendar.findMany({
          orderBy: { createdAt: 'desc' },
          select: {
            id: true,
            title: true,
            description: true,
            timezone: true,
            isActive: true,
            maxReservationMinutes: true,
            showTitleToMembers: true,
            showNotesToMembers: true,
            owner: { select: { email: true, username: true } },
            _count: { select: { members: true, reservations: true } },
          },
        })
      : [];

  /** Vereinheitlicht DB-Zeilen auf das Karten-Datenformat. */
  function toManagedCalendar(row: {
    id: string;
    title: string;
    description: string | null;
    timezone: string;
    isActive: boolean;
    maxReservationMinutes: number;
    showTitleToMembers: boolean;
    showNotesToMembers: boolean;
    owner: { email: string; username: string | null };
    _count: { members: number; reservations: number };
  }): ManagedCalendar {
    return {
      id: row.id,
      title: row.title,
      description: row.description,
      timezone: row.timezone,
      isActive: row.isActive,
      ownerEmail: row.owner.username ?? row.owner.email,
      isOwn: true,
      memberCount: row._count.members,
      reservationCount: row._count.reservations,
      maxReservationMinutes: row.maxReservationMinutes,
      showTitleToMembers: row.showTitleToMembers,
      showNotesToMembers: row.showNotesToMembers,
    };
  }

  const adminCalendars = ownedCalendars.map(toManagedCalendar);
  const userCalendar = membership?.calendar
    ? [toManagedCalendar(membership.calendar)]
    : [];

  return (
    <AppShell role={user.role} userEmail={user.email} username={user.username}>
      <header className="mb-8">
        <h1 className="text-2xl font-bold">Dashboard</h1>
      </header>

      {/* User-Ansicht: genau ein Kalender (als Karte) */}
      {user.role === 'USER' && (
        <section>
          <h2 className="mb-4 text-lg font-semibold">Mein Kalender</h2>
          {userCalendar.length === 0 ? (
            <Card>
              <p className="text-sm text-slate-600 dark:text-slate-400">
                Du bist noch keinem Kalender zugeordnet. Bitte wende dich an den
                Administrator fuer einen Einladungslink.
              </p>
            </Card>
          ) : (
            <DashboardCalendarGrid
              calendars={userCalendar}
              currentUserId={user.id}
              isAdmin={false}
            />
          )}
        </section>
      )}

      {/* Admin-Ansicht: alle Kalender als Karten (Verwaltung) */}
      {user.role === 'ADMIN' && (
        <section>
          <h2 className="mb-4 text-lg font-semibold">Kalender</h2>
          {adminCalendars.length === 0 ? (
            <Card>
              <p className="text-sm text-slate-600 dark:text-slate-400">
                Noch keine Kalender vorhanden. Erstelle deinen ersten Kalender
                unter &quot;Kalender verwalten&quot;.
              </p>
            </Card>
          ) : (
            <DashboardCalendarGrid
              calendars={adminCalendars}
              currentUserId={user.id}
              isAdmin={true}
            />
          )}
        </section>
      )}
    </AppShell>
  );
}