import React, { useEffect, useMemo, useState } from 'react';
import { Link, useParams } from 'react-router-dom';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { cn } from '@/lib/utils';
import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { Skeleton } from '@/components/ui/skeleton';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { Separator } from '@/components/ui/separator';
import {
  AchievementBadge,
  AchievementsPayload,
  FeedEntry,
  LeaderboardEntry,
  TimelinePoint,
  TopPhotoHighlight,
  TrendingEmotionHighlight,
  fetchAchievements,
} from '../services/achievementApi';
import { useGuestIdentity } from '../context/GuestIdentityContext';
import { Sparkles, Award, Trophy, Camera, Users, BarChart2, Flame } from 'lucide-react';

function formatNumber(value: number): string {
  return new Intl.NumberFormat('de-DE').format(value);
}

function formatRelativeTime(input: string): string {
  const date = new Date(input);
  if (Number.isNaN(date.getTime())) return '';
  const diff = Date.now() - date.getTime();
  const minute = 60_000;
  const hour = 60 * minute;
  const day = 24 * hour;
  if (diff < minute) return 'gerade eben';
  if (diff < hour) {
    const minutes = Math.round(diff / minute);
    return `vor ${minutes} Min`;
  }
  if (diff < day) {
    const hours = Math.round(diff / hour);
    return `vor ${hours} Std`;
  }
  const days = Math.round(diff / day);
  return `vor ${days} Tagen`;
}

function badgeVariant(earned: boolean): string {
  return earned ? 'bg-emerald-500/10 text-emerald-500 border border-emerald-500/30' : 'bg-muted text-muted-foreground';
}

function Leaderboard({ title, icon: Icon, entries, emptyCopy }: { title: string; icon: React.ElementType; entries: LeaderboardEntry[]; emptyCopy: string }) {
  return (
    <Card>
      <CardHeader className="flex flex-row items-center gap-2 pb-4">
        <div className="flex h-10 w-10 items-center justify-center rounded-full bg-pink-500/10 text-pink-500">
          <Icon className="h-5 w-5" />
        </div>
        <div>
          <CardTitle className="text-base font-semibold">{title}</CardTitle>
          <CardDescription className="text-xs">Top 5 Teilnehmer dieses Events</CardDescription>
        </div>
      </CardHeader>
      <CardContent className="space-y-2">
        {entries.length === 0 ? (
          <p className="text-sm text-muted-foreground">{emptyCopy}</p>
        ) : (
          <ol className="space-y-2 text-sm">
            {entries.map((entry, index) => (
              <li key={`${entry.guest}-${index}`} className="flex items-center justify-between rounded-lg border border-border/50 bg-muted/30 px-3 py-2">
                <div className="flex items-center gap-3">
                  <span className="text-xs font-semibold text-muted-foreground">#{index + 1}</span>
                  <span className="font-medium text-foreground">{entry.guest || 'Gast'}</span>
                </div>
                <div className="flex items-center gap-4 text-xs text-muted-foreground">
                  <span>{entry.photos} Fotos</span>
                  <span>{entry.likes} Likes</span>
                </div>
              </li>
            ))}
          </ol>
        )}
      </CardContent>
    </Card>
  );
}

function BadgesGrid({ badges }: { badges: AchievementBadge[] }) {
  if (badges.length === 0) {
    return (
      <Card>
        <CardHeader>
          <CardTitle>Badges</CardTitle>
          <CardDescription>Erfuelle Aufgaben und sammle Likes, um Badges freizuschalten.</CardDescription>
        </CardHeader>
        <CardContent>
          <p className="text-sm text-muted-foreground">Noch keine Badges verfuegbar.</p>
        </CardContent>
      </Card>
    );
  }

  return (
    <Card>
      <CardHeader>
        <CardTitle>Badges</CardTitle>
        <CardDescription>Dein Fortschritt bei den verfuegbaren Erfolgen.</CardDescription>
      </CardHeader>
      <CardContent className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
        {badges.map((badge) => (
          <div key={badge.id} className={cn('rounded-xl border px-4 py-3', badgeVariant(badge.earned))}>
            <div className="flex items-center justify-between gap-2">
              <div>
                <p className="text-sm font-semibold">{badge.title}</p>
                <p className="text-xs text-muted-foreground">{badge.description}</p>
              </div>
              <Award className="h-5 w-5" />
            </div>
            <div className="mt-2 text-xs text-muted-foreground">
              {badge.earned ? 'Abgeschlossen' : `Fortschritt: ${badge.progress}/${badge.target}`}
            </div>
          </div>
        ))}
      </CardContent>
    </Card>
  );
}

function Timeline({ points }: { points: TimelinePoint[] }) {
  if (points.length === 0) {
    return null;
  }
  return (
    <Card>
      <CardHeader>
        <CardTitle>Timeline</CardTitle>
        <CardDescription>Wie das Event im Laufe der Zeit Fahrt aufgenommen hat.</CardDescription>
      </CardHeader>
      <CardContent className="space-y-2 text-sm">
        {points.map((point) => (
          <div key={point.date} className="flex items-center justify-between rounded-lg border border-border/40 bg-muted/20 px-3 py-2">
            <span className="font-medium text-foreground">{point.date}</span>
            <span className="text-muted-foreground">{point.photos} Fotos | {point.guests} Gaeste</span>
          </div>
        ))}
      </CardContent>
    </Card>
  );
}

function Feed({ feed }: { feed: FeedEntry[] }) {
  if (feed.length === 0) {
    return (
      <Card>
        <CardHeader>
          <CardTitle>Live Feed</CardTitle>
          <CardDescription>Neue Uploads erscheinen hier in Echtzeit.</CardDescription>
        </CardHeader>
        <CardContent>
          <p className="text-sm text-muted-foreground">Noch keine Uploads - starte die Kamera und lege los!</p>
        </CardContent>
      </Card>
    );
  }

  return (
    <Card>
      <CardHeader>
        <CardTitle>Live Feed</CardTitle>
        <CardDescription>Die neuesten Momente aus deinem Event.</CardDescription>
      </CardHeader>
      <CardContent className="space-y-3">
        {feed.map((item) => (
          <div key={item.photoId} className="flex items-center gap-3 rounded-lg border border-border/40 bg-muted/20 p-3">
            {item.thumbnail ? (
              <img src={item.thumbnail} alt="Vorschau" className="h-16 w-16 rounded-md object-cover" />
            ) : (
              <div className="flex h-16 w-16 items-center justify-center rounded-md bg-muted"> <Camera className="h-6 w-6 text-muted-foreground" /> </div>
            )}
            <div className="flex-1 text-sm">
              <p className="font-semibold text-foreground">{item.guest || 'Gast'}</p>
              {item.task && <p className="text-xs text-muted-foreground">Aufgabe: {item.task}</p>}
              <div className="mt-1 flex items-center gap-4 text-xs text-muted-foreground">
                <span>{formatRelativeTime(item.createdAt)}</span>
                <span>{item.likes} Likes</span>
              </div>
            </div>
          </div>
        ))}
      </CardContent>
    </Card>
  );
}

function Highlights({ topPhoto, trendingEmotion }: { topPhoto: TopPhotoHighlight | null; trendingEmotion: TrendingEmotionHighlight | null }) {
  if (!topPhoto && !trendingEmotion) {
    return null;
  }

  return (
    <div className="grid gap-4 md:grid-cols-2">
      {topPhoto && (
        <Card>
          <CardHeader className="flex flex-row items-center justify-between">
            <div>
              <CardTitle>Publikumsliebling</CardTitle>
              <CardDescription>Das Foto mit den meisten Likes.</CardDescription>
            </div>
            <Trophy className="h-6 w-6 text-amber-400" />
          </CardHeader>
          <CardContent className="space-y-2 text-sm">
            <div className="overflow-hidden rounded-xl border border-border/40">
              {topPhoto.thumbnail ? (
                <img src={topPhoto.thumbnail} alt="Top Foto" className="h-48 w-full object-cover" />
              ) : (
                <div className="flex h-48 w-full items-center justify-center bg-muted text-muted-foreground">Kein Vorschau-Bild</div>
              )}
            </div>
            <p><span className="font-semibold text-foreground">{topPhoto.guest || 'Gast'}</span> � {topPhoto.likes} Likes</p>
            {topPhoto.task && <p className="text-muted-foreground">Aufgabe: {topPhoto.task}</p>}
            <p className="text-xs text-muted-foreground">{formatRelativeTime(topPhoto.createdAt)}</p>
          </CardContent>
        </Card>
      )}

      {trendingEmotion && (
        <Card>
          <CardHeader className="flex flex-row items-center justify-between">
            <div>
              <CardTitle>Trend-Emotion</CardTitle>
              <CardDescription>Diese Stimmung taucht gerade besonders oft auf.</CardDescription>
            </div>
            <Flame className="h-6 w-6 text-pink-500" />
          </CardHeader>
          <CardContent>
            <p className="text-lg font-semibold text-foreground">{trendingEmotion.name}</p>
            <p className="text-sm text-muted-foreground">{trendingEmotion.count} Fotos mit dieser Stimmung</p>
          </CardContent>
        </Card>
      )}
    </div>
  );
}

function SummaryCards({ data }: { data: AchievementsPayload }) {
  return (
    <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-4">
      <Card>
        <CardContent className="flex flex-col gap-1 py-4">
          <span className="text-xs uppercase text-muted-foreground">Fotos gesamt</span>
          <span className="text-2xl font-semibold text-foreground">{formatNumber(data.summary.totalPhotos)}</span>
        </CardContent>
      </Card>
      <Card>
        <CardContent className="flex flex-col gap-1 py-4">
          <span className="text-xs uppercase text-muted-foreground">Aktive Gaeste</span>
          <span className="text-2xl font-semibold text-foreground">{formatNumber(data.summary.uniqueGuests)}</span>
        </CardContent>
      </Card>
      <Card>
        <CardContent className="flex flex-col gap-1 py-4">
          <span className="text-xs uppercase text-muted-foreground">Erfuellte Aufgaben</span>
          <span className="text-2xl font-semibold text-foreground">{formatNumber(data.summary.tasksSolved)}</span>
        </CardContent>
      </Card>
      <Card>
        <CardContent className="flex flex-col gap-1 py-4">
          <span className="text-xs uppercase text-muted-foreground">Likes insgesamt</span>
          <span className="text-2xl font-semibold text-foreground">{formatNumber(data.summary.likesTotal)}</span>
        </CardContent>
      </Card>
    </div>
  );
}

function PersonalActions({ slug }: { slug: string }) {
  return (
    <div className="flex flex-wrap gap-3">
      <Button asChild>
        <Link to={`/e/${encodeURIComponent(slug)}/upload`} className="flex items-center gap-2">
          <Camera className="h-4 w-4" />
          Neues Foto hochladen
        </Link>
      </Button>
      <Button variant="outline" asChild>
        <Link to={`/e/${encodeURIComponent(slug)}/tasks`} className="flex items-center gap-2">
          <Sparkles className="h-4 w-4" />
          Aufgabe ziehen
        </Link>
      </Button>
    </div>
  );
}

export default function AchievementsPage() {
  const { slug } = useParams<{ slug: string }>();
  const identity = useGuestIdentity();
  const [data, setData] = useState<AchievementsPayload | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [activeTab, setActiveTab] = useState<'personal' | 'event' | 'feed'>('personal');

  const personalName = identity.hydrated && identity.name ? identity.name : undefined;

  useEffect(() => {
    if (!slug) return;
    const controller = new AbortController();
    setLoading(true);
    setError(null);

    fetchAchievements(slug, personalName, controller.signal)
      .then((payload) => {
        setData(payload);
        if (!payload.personal) {
          setActiveTab('event');
        }
      })
      .catch((err) => {
        if (err.name === 'AbortError') return;
        console.error('Failed to load achievements', err);
        setError(err.message || 'Erfolge konnten nicht geladen werden.');
      })
      .finally(() => setLoading(false));

    return () => controller.abort();
  }, [slug, personalName]);

  const hasPersonal = Boolean(data?.personal);

  if (!slug) {
    return null;
  }

  return (
    <div className="space-y-6 pb-24">
      <div className="space-y-2">
        <div className="flex items-center gap-3">
          <div className="flex h-10 w-10 items-center justify-center rounded-full bg-pink-500/10 text-pink-500">
            <Award className="h-5 w-5" />
          </div>
          <div>
            <h1 className="text-2xl font-semibold text-foreground">Erfolge</h1>
            <p className="text-sm text-muted-foreground">Behalte deine Highlights, Badges und die aktivsten Gaeste im Blick.</p>
          </div>
        </div>
      </div>

      {loading && (
        <div className="space-y-4">
          <Skeleton className="h-24 w-full" />
          <Skeleton className="h-32 w-full" />
          <Skeleton className="h-48 w-full" />
        </div>
      )}

      {!loading && error && (
        <Alert variant="destructive">
          <AlertDescription className="flex items-center justify-between gap-3">
            <span>{error}</span>
            <Button variant="outline" size="sm" onClick={() => setActiveTab(hasPersonal ? 'personal' : 'event')}>
              Erneut versuchen
            </Button>
          </AlertDescription>
        </Alert>
      )}

      {!loading && !error && data && (
        <>
          <SummaryCards data={data} />

          <div className="flex flex-wrap items-center gap-2">
            <Button
              variant={activeTab === 'personal' ? 'default' : 'outline'}
              onClick={() => setActiveTab('personal')}
              disabled={!hasPersonal}
              className="flex items-center gap-2"
            >
              <Sparkles className="h-4 w-4" />
              Meine Erfolge
            </Button>
            <Button
              variant={activeTab === 'event' ? 'default' : 'outline'}
              onClick={() => setActiveTab('event')}
              className="flex items-center gap-2"
            >
              <Users className="h-4 w-4" />
              Event Highlights
            </Button>
            <Button
              variant={activeTab === 'feed' ? 'default' : 'outline'}
              onClick={() => setActiveTab('feed')}
              className="flex items-center gap-2"
            >
              <BarChart2 className="h-4 w-4" />
              Live Feed
            </Button>
          </div>

          <Separator />

          {activeTab === 'personal' && hasPersonal && data.personal && (
            <div className="space-y-5">
              <Card>
                <CardHeader className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
                  <div>
                    <CardTitle className="text-lg font-semibold">Hi {data.personal.guestName || identity.name || 'Gast'}!</CardTitle>
                    <CardDescription>
                      {data.personal.photos} Fotos | {data.personal.tasks} Aufgaben | {data.personal.likes} Likes
                    </CardDescription>
                  </div>
                  <PersonalActions slug={slug} />
                </CardHeader>
              </Card>

              <BadgesGrid badges={data.personal.badges} />
            </div>
          )}

          {activeTab === 'event' && (
            <div className="space-y-5">
              <Highlights topPhoto={data.highlights.topPhoto} trendingEmotion={data.highlights.trendingEmotion} />
              <Timeline points={data.highlights.timeline} />
              <div className="grid gap-4 lg:grid-cols-2">
                <Leaderboard
                  title="Top Uploads"
                  icon={Users}
                  entries={data.leaderboards.uploads}
                  emptyCopy="Noch keine Uploads - sobald Fotos vorhanden sind, erscheinen sie hier."
                />
                <Leaderboard
                  title="Beliebteste Gaeste"
                  icon={Trophy}
                  entries={data.leaderboards.likes}
                  emptyCopy="Likes fehlen noch - motiviere die Gaeste, Fotos zu liken."
                />
              </div>
            </div>
          )}

          {activeTab === 'feed' && <Feed feed={data.feed} />}
        </>
      )}
    </div>
  );
}