import Link from 'next/link';

import { ChevronLeft, ChevronRight, GraduationCap, Plus, Users, Calendar, Euro } 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 { createCourseManagementApi } from '@kit/course-management/api';

import { CmsPageShell } from '~/components/cms-page-shell';
import { EmptyState } from '~/components/empty-state';
import { StatsCard } from '~/components/stats-card';
import { AccountNotFound } from '~/components/account-not-found';
import { COURSE_STATUS_VARIANT, COURSE_STATUS_LABEL } from '~/lib/status-badges';

interface PageProps {
  params: Promise<{ account: string }>;
  searchParams: Promise<Record<string, string | string[] | undefined>>;
}

const PAGE_SIZE = 25;

export default async function CoursesPage({ params, searchParams }: PageProps) {
  const { account } = await params;
  const search = await searchParams;
  const client = getSupabaseServerClient();

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

  if (!acct) return <AccountNotFound />;

  const api = createCourseManagementApi(client);
  const page = Number(search.page) || 1;

  const [courses, stats] = await Promise.all([
    api.listCourses(acct.id, { page, pageSize: PAGE_SIZE }),
    api.getStatistics(acct.id),
  ]);

  const totalPages = Math.ceil(courses.total / PAGE_SIZE);

  return (
    <CmsPageShell account={account} title="Kurse">
      <div className="flex w-full flex-col gap-6">
        {/* Header */}
        <div className="flex items-center justify-between">
          <p className="text-muted-foreground">
            Kursangebot verwalten
          </p>

          <Link href={`/home/${account}/courses/new`}>
            <Button>
              <Plus className="mr-2 h-4 w-4" />
              Neuer Kurs
            </Button>
          </Link>
        </div>

        {/* Stats */}
        <div className="grid grid-cols-1 gap-4 sm:grid-cols-2 lg:grid-cols-4">
          <StatsCard
            title="Gesamt"
            value={stats.totalCourses}
            icon={<GraduationCap className="h-5 w-5" />}
          />
          <StatsCard
            title="Aktiv"
            value={stats.openCourses}
            icon={<Calendar className="h-5 w-5" />}
          />
          <StatsCard
            title="Abgeschlossen"
            value={stats.completedCourses}
            icon={<GraduationCap className="h-5 w-5" />}
          />
          <StatsCard
            title="Teilnehmer"
            value={stats.totalParticipants}
            icon={<Users className="h-5 w-5" />}
          />
        </div>

        {/* Table or Empty State */}
        {courses.data.length === 0 ? (
          <EmptyState
            icon={<GraduationCap className="h-8 w-8" />}
            title="Keine Kurse vorhanden"
            description="Erstellen Sie Ihren ersten Kurs, um loszulegen."
            actionLabel="Neuer Kurs"
            actionHref={`/home/${account}/courses/new`}
          />
        ) : (
          <Card>
            <CardHeader>
              <CardTitle>Alle Kurse ({courses.total})</CardTitle>
            </CardHeader>
            <CardContent>
              <div className="rounded-md border">
                <table className="w-full text-sm">
                  <thead>
                    <tr className="border-b bg-muted/50">
                      <th className="p-3 text-left font-medium">Kursnr.</th>
                      <th className="p-3 text-left font-medium">Name</th>
                      <th className="p-3 text-left font-medium">Beginn</th>
                      <th className="p-3 text-left font-medium">Ende</th>
                      <th className="p-3 text-left font-medium">Status</th>
                      <th className="p-3 text-right font-medium">Kapazität</th>
                      <th className="p-3 text-right font-medium">Gebühr</th>
                    </tr>
                  </thead>
                  <tbody>
                    {courses.data.map((course: Record<string, unknown>) => (
                      <tr key={String(course.id)} className="border-b hover:bg-muted/30">
                        <td className="p-3 font-mono text-xs">
                          {String(course.course_number ?? '—')}
                        </td>
                        <td className="p-3 font-medium">
                          <Link
                            href={`/home/${account}/courses/${String(course.id)}`}
                            className="hover:underline"
                          >
                            {String(course.name)}
                          </Link>
                        </td>
                        <td className="p-3">
                          {course.start_date
                            ? new Date(String(course.start_date)).toLocaleDateString('de-DE')
                            : '—'}
                        </td>
                        <td className="p-3">
                          {course.end_date
                            ? new Date(String(course.end_date)).toLocaleDateString('de-DE')
                            : '—'}
                        </td>
                        <td className="p-3">
                          <Badge
                            variant={COURSE_STATUS_VARIANT[String(course.status)] ?? 'secondary'}
                          >
                            {COURSE_STATUS_LABEL[String(course.status)] ?? String(course.status)}
                          </Badge>
                        </td>
                        <td className="p-3 text-right">
                          {course.capacity != null
                            ? String(course.capacity)
                            : '—'}
                        </td>
                        <td className="p-3 text-right">
                          {course.fee != null
                            ? `${Number(course.fee).toFixed(2)} €`
                            : '—'}
                        </td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              </div>

              {/* Pagination */}
              {totalPages > 1 && (
                <div className="flex items-center justify-between border-t px-2 py-4">
                  <p className="text-sm text-muted-foreground">
                    Seite {page} von {totalPages} ({courses.total} Einträge)
                  </p>
                  <div className="flex items-center gap-2">
                    {page > 1 ? (
                      <Link href={`/home/${account}/courses?page=${page - 1}`}>
                        <Button variant="outline" size="sm">
                          <ChevronLeft className="mr-1 h-4 w-4" />
                          Zurück
                        </Button>
                      </Link>
                    ) : (
                      <Button variant="outline" size="sm" disabled>
                        <ChevronLeft className="mr-1 h-4 w-4" />
                        Zurück
                      </Button>
                    )}

                    {page < totalPages ? (
                      <Link href={`/home/${account}/courses?page=${page + 1}`}>
                        <Button variant="outline" size="sm">
                          Weiter
                          <ChevronRight className="ml-1 h-4 w-4" />
                        </Button>
                      </Link>
                    ) : (
                      <Button variant="outline" size="sm" disabled>
                        Weiter
                        <ChevronRight className="ml-1 h-4 w-4" />
                      </Button>
                    )}
                  </div>
                </div>
              )}
            </CardContent>
          </Card>
        )}
      </div>
    </CmsPageShell>
  );
}
