import Link from "next/link";
import type { Metadata } from "next";
import { requireUser } from "@/lib/auth";
import { getSettings } from "@/lib/settings";
import {
  getActiveYears,
  getGenreDistribution,
  getMonthlyActivity,
  getMostWatched,
  getProviderDistribution,
  getTopRated,
  getTotals,
  getYearReview,
} from "@/lib/stats";
import { formatMinutes } from "@/lib/labels";
import { AppShell } from "@/components/AppShell";
import { Poster } from "@/components/Poster";
import { DistributionBars, MonthlyChart } from "@/components/stats/Charts";

export const metadata: Metadata = { title: "Statistik" };

export default async function StatsPage({
  searchParams,
}: {
  searchParams: Promise<{ jahr?: string }>;
}) {
  const user = await requireUser("/statistik");
  const settings = await getSettings();
  const params = await searchParams;

  const years = await getActiveYears(user.id);
  const requested = Number.parseInt(params.jahr ?? "", 10);
  const year = years.includes(requested) ? requested : (years[0] ?? new Date().getFullYear());

  const [totals, monthly, providers, genres, topRated, mostWatched, review] = await Promise.all([
    getTotals(user.id),
    getMonthlyActivity(user.id, 12),
    getProviderDistribution(user.id),
    getGenreDistribution(user.id),
    getTopRated(user.id, 5),
    getMostWatched(user.id, 5),
    getYearReview(user.id, year),
  ]);

  if (totals.minutes === 0 && totals.episodes === 0 && totals.movies === 0) {
    return (
      <AppShell user={user} instanceName={settings.instanceName}>
        <header className="mb-5">
          <h1 className="text-2xl font-semibold tracking-tight sm:text-3xl">Statistik</h1>
        </header>
        <div className="fl-card p-8 text-center">
          <p className="mx-auto max-w-md text-[var(--fl-muted)]">
            Noch keine Sichtungen. Sobald du die erste Episode abhakst, entstehen hier
            Schauzeit, Verteilungen und der Jahresrückblick.
          </p>
          <Link href="/bibliothek" className="fl-btn fl-btn-primary mt-4">
            Zur Bibliothek
          </Link>
        </div>
      </AppShell>
    );
  }

  const days = totals.minutes / (60 * 24);

  return (
    <AppShell user={user} instanceName={settings.instanceName}>
      <header className="mb-6">
        <h1 className="text-2xl font-semibold tracking-tight sm:text-3xl">Statistik</h1>
        <p className="mt-1 text-sm text-[var(--fl-muted)]">
          Alles gerechnet aus deinen Sichtungen — Rewatches zählen mit.
        </p>
      </header>

      <section className="fl-card mb-6 p-5 sm:p-7" aria-label="Gesamtschauzeit">
        <p className="text-sm font-medium text-[var(--fl-muted)]">Gesamte Schauzeit</p>
        <p className="fl-gradient-text mt-1 text-5xl font-semibold tabular-nums sm:text-6xl">
          {Math.round(totals.minutes / 60).toLocaleString("de-DE")} h
        </p>
        <p className="mt-1 text-sm text-[var(--fl-muted)]">
          {formatMinutes(totals.minutes)} · das sind {days.toFixed(1).replace(".", ",")} Tage am Stück
        </p>

        <dl className="mt-5 grid grid-cols-2 gap-4 sm:grid-cols-4">
          <Stat label="Episoden" value={totals.episodes.toLocaleString("de-DE")} />
          <Stat label="Filme" value={totals.movies.toLocaleString("de-DE")} />
          <Stat label="Abgeschlossen" value={totals.titlesCompleted.toLocaleString("de-DE")} />
          <Stat
            label="In der Bibliothek"
            value={`${totals.seriesCount} Serien · ${totals.movieCount} Filme`}
          />
        </dl>
      </section>

      <section className="fl-card mb-6 p-5" aria-labelledby="verlauf">
        <h2 id="verlauf" className="mb-1 text-lg font-semibold">
          Die letzten zwölf Monate
        </h2>
        <p className="mb-4 text-sm text-[var(--fl-muted)]">
          Abgehakte Episoden und Filme je Monat.
        </p>
        <MonthlyChart points={monthly.map(({ label, episodes, movies, minutes }) => ({ label, episodes, movies, minutes }))} />
      </section>

      <div className="mb-6 grid gap-6 lg:grid-cols-2">
        <section className="fl-card p-5" aria-labelledby="dienste">
          <h2 id="dienste" className="mb-1 text-lg font-semibold">
            Nach Streamingdienst
          </h2>
          <p className="mb-4 text-sm text-[var(--fl-muted)]">
            Wo du tatsächlich geschaut hast — aus dem Feld „wo schaue ich das".
          </p>
          <DistributionBars
            rows={providers.slice(0, 8)}
            emptyText="Noch keine Sichtung einem Dienst zugeordnet."
            useBrandColors
          />
        </section>

        <section className="fl-card p-5" aria-labelledby="genres">
          <h2 id="genres" className="mb-1 text-lg font-semibold">
            Nach Genre
          </h2>
          <p className="mb-4 text-sm text-[var(--fl-muted)]">
            Titel mit mehreren Genres zählen in jedem mit.
          </p>
          <DistributionBars rows={genres.slice(0, 8)} emptyText="Noch keine Genres erfasst." />
        </section>
      </div>

      <section className="fl-card mb-6 p-5" aria-labelledby="rueckblick">
        <div className="mb-4 flex flex-wrap items-center justify-between gap-3">
          <h2 id="rueckblick" className="text-lg font-semibold">
            {review.year} in Zahlen
          </h2>
          {years.length > 1 && (
            <div className="flex flex-wrap gap-1.5" role="group" aria-label="Jahr wählen">
              {years.slice(0, 6).map((entry) => (
                <Link
                  key={entry}
                  href={`/statistik?jahr=${entry}`}
                  aria-current={entry === review.year ? "true" : undefined}
                  className="rounded-full border px-3 py-1 text-sm font-medium transition-colors"
                  style={
                    entry === review.year
                      ? {
                          backgroundImage: "var(--fl-gradient)",
                          color: "var(--fl-on-accent)",
                          borderColor: "transparent",
                        }
                      : { borderColor: "var(--fl-border)", color: "var(--fl-muted)" }
                  }
                >
                  {entry}
                </Link>
              ))}
            </div>
          )}
        </div>

        <dl className="grid grid-cols-2 gap-4 sm:grid-cols-3 lg:grid-cols-5">
          <Stat label="Schauzeit" value={formatMinutes(review.minutes)} />
          <Stat label="Episoden" value={review.episodes.toLocaleString("de-DE")} />
          <Stat label="Filme" value={review.movies.toLocaleString("de-DE")} />
          <Stat label="Neu angefangen" value={review.titlesStarted.toLocaleString("de-DE")} />
          <Stat label="Abgeschlossen" value={review.titlesCompleted.toLocaleString("de-DE")} />
        </dl>

        <div className="mt-5 grid gap-4 sm:grid-cols-2">
          {review.busiestMonth && (
            <p className="rounded-xl border border-[var(--fl-border)] p-3 text-sm">
              <span className="text-[var(--fl-faint)]">Stärkster Monat: </span>
              <span className="font-medium">{review.busiestMonth.label}</span>
              <span className="text-[var(--fl-muted)]">
                {" "}
                mit {formatMinutes(review.busiestMonth.minutes)}
              </span>
            </p>
          )}
          {review.topTitle && (
            <p className="rounded-xl border border-[var(--fl-border)] p-3 text-sm">
              <span className="text-[var(--fl-faint)]">Die meiste Zeit ging an: </span>
              <Link href={`/titel/${review.topTitle.titleId}`} className="font-medium hover:text-[var(--fl-accent)]">
                {review.topTitle.title}
              </Link>
              <span className="text-[var(--fl-muted)]"> ({formatMinutes(review.topTitle.minutes)})</span>
            </p>
          )}
        </div>
      </section>

      <div className="grid gap-6 lg:grid-cols-2">
        <TitleList
          id="meistzeit"
          heading="Wo die meiste Zeit hinging"
          items={mostWatched}
          renderMeta={(item) => formatMinutes(item.minutes)}
          emptyText="Noch nichts gesehen."
        />
        <TitleList
          id="bestbewertet"
          heading="Deine besten Bewertungen"
          items={topRated}
          renderMeta={(item) => (item.rating ? `${item.rating}/10` : "—")}
          emptyText="Noch nichts bewertet."
        />
      </div>
    </AppShell>
  );
}

function Stat({ label, value }: { label: string; value: string }) {
  return (
    <div>
      <dt className="text-xs uppercase tracking-wide text-[var(--fl-faint)]">{label}</dt>
      <dd className="mt-0.5 text-lg font-semibold tabular-nums">{value}</dd>
    </div>
  );
}

function TitleList({
  id,
  heading,
  items,
  renderMeta,
  emptyText,
}: {
  id: string;
  heading: string;
  items: { titleId: string; title: string; posterPath: string | null; rating: number | null; minutes: number; type: string }[];
  renderMeta: (item: { rating: number | null; minutes: number }) => string;
  emptyText: string;
}) {
  return (
    <section className="fl-card p-5" aria-labelledby={id}>
      <h2 id={id} className="mb-4 text-lg font-semibold">
        {heading}
      </h2>

      {items.length === 0 ? (
        <p className="text-sm text-[var(--fl-faint)]">{emptyText}</p>
      ) : (
        <ol className="space-y-3">
          {items.map((item, index) => (
            <li key={item.titleId} className="flex items-center gap-3">
              <span className="w-4 shrink-0 text-right font-mono text-sm text-[var(--fl-faint)]">
                {index + 1}
              </span>
              <Link href={`/titel/${item.titleId}`} className="w-10 shrink-0">
                <Poster path={item.posterPath} alt={item.title} size="w154" />
              </Link>
              <Link
                href={`/titel/${item.titleId}`}
                className="min-w-0 flex-1 truncate text-sm font-medium hover:text-[var(--fl-accent)]"
              >
                {item.title}
              </Link>
              <span className="shrink-0 text-sm tabular-nums text-[var(--fl-muted)]">
                {renderMeta(item)}
              </span>
            </li>
          ))}
        </ol>
      )}
    </section>
  );
}