import Link from 'next/link';

import { CalendarDays, ClipboardList, Users } from 'lucide-react';

import { getSupabaseServerClient } from '@kit/supabase/server-client';
import { Badge } from '@kit/ui/badge';
import { Button } from '@kit/ui/button';
import { Card, CardContent, CardHeader, CardTitle } from '@kit/ui/card';

import { createEventManagementApi } from '@kit/event-management/api';

import { CmsPageShell } from '~/components/cms-page-shell';
import { EmptyState } from '~/components/empty-state';
import { StatsCard } from '~/components/stats-card';

interface PageProps {
  params: Promise<{ account: string }>;
}

export default async function EventRegistrationsPage({ params }: PageProps) {
  const { account } = await params;
  const client = getSupabaseServerClient();

  const { data: acct } = await client
    .from('accounts')
    .select('id')
    .eq('slug', account)
    .single();

  if (!acct) return <div>Konto nicht gefunden</div>;

  const api = createEventManagementApi(client);
  const events = await api.listEvents(acct.id, { page: 1 });

  // Load registrations for each event in parallel
  const eventsWithRegistrations = await Promise.all(
    events.data.map(async (event: Record<string, unknown>) => {
      const registrations = await api.getRegistrations(String(event.id));
      return {
        id: String(event.id),
        name: String(event.name),
        eventDate: event.event_date ? String(event.event_date) : null,
        status: String(event.status ?? 'draft'),
        capacity: event.capacity != null ? Number(event.capacity) : null,
        registrationCount: registrations.length,
      };
    }),
  );

  const totalRegistrations = eventsWithRegistrations.reduce(
    (sum, e) => sum + e.registrationCount,
    0,
  );
  const eventsWithRegs = eventsWithRegistrations.filter(
    (e) => e.registrationCount > 0,
  );

  return (
    <CmsPageShell account={account} title="Anmeldungen">
      <div className="flex w-full flex-col gap-6">
        {/* Header */}
        <div>
          <h1 className="text-2xl font-bold">Anmeldungen</h1>
          <p className="text-muted-foreground">
            Anmeldungen aller Veranstaltungen im Überblick
          </p>
        </div>

        {/* Stats */}
        <div className="grid grid-cols-1 gap-4 sm:grid-cols-3">
          <StatsCard
            title="Veranstaltungen"
            value={events.total}
            icon={<CalendarDays className="h-5 w-5" />}
          />
          <StatsCard
            title="Anmeldungen gesamt"
            value={totalRegistrations}
            icon={<ClipboardList className="h-5 w-5" />}
          />
          <StatsCard
            title="Mit Anmeldungen"
            value={eventsWithRegs.length}
            icon={<Users className="h-5 w-5" />}
          />
        </div>

        {/* Registration Summary Table */}
        {eventsWithRegistrations.length === 0 ? (
          <EmptyState
            icon={<ClipboardList className="h-8 w-8" />}
            title="Keine Veranstaltungen vorhanden"
            description="Erstellen Sie eine Veranstaltung, um Anmeldungen zu erhalten."
            actionLabel="Neue Veranstaltung"
            actionHref={`/home/${account}/events/new`}
          />
        ) : (
          <Card>
            <CardHeader>
              <CardTitle>
                Übersicht nach Veranstaltung ({eventsWithRegistrations.length})
              </CardTitle>
            </CardHeader>
            <CardContent>
              <div className="rounded-md border">
                <table className="w-full text-sm">
                  <thead>
                    <tr className="border-b bg-muted/50">
                      <th className="p-3 text-left font-medium">
                        Veranstaltung
                      </th>
                      <th className="p-3 text-left font-medium">Datum</th>
                      <th className="p-3 text-left font-medium">Status</th>
                      <th className="p-3 text-right font-medium">Kapazität</th>
                      <th className="p-3 text-right font-medium">
                        Anmeldungen
                      </th>
                      <th className="p-3 text-right font-medium">Auslastung</th>
                    </tr>
                  </thead>
                  <tbody>
                    {eventsWithRegistrations.map((event) => {
                      const utilization =
                        event.capacity && event.capacity > 0
                          ? Math.round(
                              (event.registrationCount / event.capacity) * 100,
                            )
                          : null;

                      return (
                        <tr
                          key={event.id}
                          className="border-b hover:bg-muted/30"
                        >
                          <td className="p-3 font-medium">
                            <Link
                              href={`/home/${account}/events/${event.id}`}
                              className="hover:underline"
                            >
                              {event.name}
                            </Link>
                          </td>
                          <td className="p-3">
                            {event.eventDate
                              ? new Date(event.eventDate).toLocaleDateString(
                                  'de-DE',
                                )
                              : '—'}
                          </td>
                          <td className="p-3">
                            <Badge variant="outline">{event.status}</Badge>
                          </td>
                          <td className="p-3 text-right">
                            {event.capacity ?? '—'}
                          </td>
                          <td className="p-3 text-right font-medium">
                            {event.registrationCount}
                          </td>
                          <td className="p-3 text-right">
                            {utilization !== null ? (
                              <Badge
                                variant={
                                  utilization >= 90
                                    ? 'destructive'
                                    : utilization >= 70
                                      ? 'default'
                                      : 'secondary'
                                }
                              >
                                {utilization}%
                              </Badge>
                            ) : (
                              <span className="text-muted-foreground">—</span>
                            )}
                          </td>
                        </tr>
                      );
                    })}
                  </tbody>
                </table>
              </div>
            </CardContent>
          </Card>
        )}
      </div>
    </CmsPageShell>
  );
}