feat: Auswertungen für Übersicht, Kalender und Statistik

Alles wird aus den Sichtungen berechnet — es gibt keine fortgeschriebenen
Zähler, die auseinanderlaufen könnten. Zeitreihen laufen als SQL, weil Prisma
keine Gruppierung nach Monat kennt.

Der Monatsschlüssel kommt bewusst als Text aus der Datenbank: date_trunc
liefert Mitternacht in der Sitzungszeitzone, JavaScript legt beim Vergleich
die lokale Zone an — zwei Stunden Versatz genügen, damit kein Schlüssel mehr
passt und das Diagramm leer bleibt.

src/lib/stats.ts

@@ -0,0 +1,557 @@
+import "server-only";
+import { prisma } from "./db";
+import { SPECIALS_SEASON } from "./catalog";
+
+/**
+ * Auswertungen für Übersicht, Kalender und Statistik.
+ *
+ * Alles wird aus den Sichtungen (`Watch`) berechnet — es gibt keine
+ * fortgeschriebenen Zähler, die auseinanderlaufen könnten. Wo es auf Tempo
+ * ankommt, laufen die Abfragen als SQL, weil Prisma für Zeitreihen keine
+ * Gruppierung nach Monat kennt.
+ */
+
+// ---------------------------------------------------------------------------
+// Übersicht
+// ---------------------------------------------------------------------------
+
+export type ContinueItem = {
+  entryId: string;
+  titleId: string;
+  title: string;
+  posterPath: string | null;
+  watched: number;
+  total: number;
+  percent: number;
+  lastWatchedAt: Date | null;
+  next: {
+    id: string;
+    name: string;
+    seasonNumber: number;
+    episodeNumber: number;
+    airDate: Date | null;
+    runtime: number | null;
+  } | null;
+};
+
+/**
+ * „Weiterschauen": laufende Serien, zuletzt angefasste zuerst.
+ * Serien ohne offene Episode fallen heraus — die sind durch.
+ */
+export async function getContinueWatching(userId: string, limit = 12): Promise<ContinueItem[]> {
+  const entries = await prisma.libraryEntry.findMany({
+    where: {
+      userId,
+      deletedAt: null,
+      status: { in: ["WATCHING", "PAUSED"] },
+      title: { type: "SERIES" },
+    },
+    orderBy: { updatedAt: "desc" },
+    take: limit * 2,
+    select: {
+      id: true,
+      titleId: true,
+      currentRun: true,
+      updatedAt: true,
+      title: { select: { title: true, posterPath: true, episodeCount: true } },
+    },
+  });
+
+  if (entries.length === 0) return [];
+
+  const items: ContinueItem[] = [];
+
+  for (const entry of entries) {
+    const [watched, next, lastWatch] = await Promise.all([
+      prisma.watch.count({
+        where: {
+          userId,
+          entryId: entry.id,
+          run: entry.currentRun,
+          episode: { seasonNumber: { gt: SPECIALS_SEASON } },
+        },
+      }),
+      prisma.episode.findFirst({
+        where: {
+          titleId: entry.titleId,
+          seasonNumber: { gt: SPECIALS_SEASON },
+          watches: { none: { userId, run: entry.currentRun } },
+        },
+        orderBy: [{ seasonNumber: "asc" }, { episodeNumber: "asc" }],
+        select: {
+          id: true,
+          name: true,
+          seasonNumber: true,
+          episodeNumber: true,
+          airDate: true,
+          runtime: true,
+        },
+      }),
+      prisma.watch.findFirst({
+        where: { userId, entryId: entry.id, run: entry.currentRun },
+        orderBy: { watchedAt: "desc" },
+        select: { watchedAt: true },
+      }),
+    ]);
+
+    if (!next) continue;
+
+    const total = entry.title.episodeCount;
+    items.push({
+      entryId: entry.id,
+      titleId: entry.titleId,
+      title: entry.title.title,
+      posterPath: entry.title.posterPath,
+      watched,
+      total,
+      percent: total > 0 ? Math.round((watched / total) * 100) : 0,
+      lastWatchedAt: lastWatch?.watchedAt ?? null,
+      next,
+    });
+
+    if (items.length >= limit) break;
+  }
+
+  return items;
+}
+
+export type UpcomingEpisode = {
+  episodeId: string;
+  titleId: string;
+  title: string;
+  posterPath: string | null;
+  name: string;
+  seasonNumber: number;
+  episodeNumber: number;
+  airDate: Date;
+  runtime: number | null;
+};
+
+/**
+ * Kommende Episoden getrackter Serien.
+ *
+ * „Getrackt" heißt: in der Bibliothek und nicht abgebrochen. Abgeschlossene
+ * Serien bleiben bewusst drin — wer bei einer laufenden Serie auf dem Stand
+ * ist, gilt als „abgeschlossen" und will die nächste Folge erst recht im
+ * Kalender sehen. Nur Abgebrochenes fällt heraus.
+ */
+export async function getUpcomingEpisodes(
+  userId: string,
+  from: Date,
+  to: Date,
+): Promise<UpcomingEpisode[]> {
+  const episodes = await prisma.episode.findMany({
+    where: {
+      airDate: { gte: from, lte: to },
+      seasonNumber: { gt: SPECIALS_SEASON },
+      title: {
+        entries: {
+          some: { userId, deletedAt: null, status: { not: "DROPPED" } },
+        },
+      },
+    },
+    orderBy: [{ airDate: "asc" }, { seasonNumber: "asc" }, { episodeNumber: "asc" }],
+    select: {
+      id: true,
+      name: true,
+      seasonNumber: true,
+      episodeNumber: true,
+      airDate: true,
+      runtime: true,
+      title: { select: { id: true, title: true, posterPath: true } },
+    },
+  });
+
+  return episodes.flatMap((episode) =>
+    episode.airDate
+      ? [
+          {
+            episodeId: episode.id,
+            titleId: episode.title.id,
+            title: episode.title.title,
+            posterPath: episode.title.posterPath,
+            name: episode.name,
+            seasonNumber: episode.seasonNumber,
+            episodeNumber: episode.episodeNumber,
+            airDate: episode.airDate,
+            runtime: episode.runtime,
+          },
+        ]
+      : [],
+  );
+}
+
+export type AvailableItem = {
+  titleId: string;
+  title: string;
+  posterPath: string | null;
+  providers: { name: string; color: string | null }[];
+  since: Date;
+};
+
+/**
+ * Watchlist-Titel, die seit Kurzem auf einem Dienst verfügbar sind.
+ * Grundlage ist `firstSeenAt` der Verfügbarkeit — das steht seit dem ersten
+ * Abgleich fest und wandert nicht bei jedem Sync weiter.
+ */
+export async function getNewlyAvailable(
+  userId: string,
+  region: string,
+  sinceDays = 30,
+): Promise<AvailableItem[]> {
+  const since = new Date(Date.now() - sinceDays * 86_400_000);
+
+  const rows = await prisma.titleProvider.findMany({
+    where: {
+      region,
+      kind: { in: ["FLATRATE", "FREE", "ADS"] },
+      firstSeenAt: { gte: since },
+      title: { entries: { some: { userId, deletedAt: null, status: "WATCHLIST" } } },
+    },
+    orderBy: { firstSeenAt: "desc" },
+    select: {
+      firstSeenAt: true,
+      provider: { select: { name: true, color: true } },
+      title: { select: { id: true, title: true, posterPath: true } },
+    },
+  });
+
+  const byTitle = new Map<string, AvailableItem>();
+  for (const row of rows) {
+    const existing = byTitle.get(row.title.id);
+    if (existing) {
+      if (!existing.providers.some((provider) => provider.name === row.provider.name)) {
+        existing.providers.push(row.provider);
+      }
+      continue;
+    }
+    byTitle.set(row.title.id, {
+      titleId: row.title.id,
+      title: row.title.title,
+      posterPath: row.title.posterPath,
+      providers: [row.provider],
+      since: row.firstSeenAt,
+    });
+  }
+
+  return [...byTitle.values()];
+}
+
+// ---------------------------------------------------------------------------
+// Statistik
+// ---------------------------------------------------------------------------
+
+export type Totals = {
+  minutes: number;
+  episodes: number;
+  movies: number;
+  titlesCompleted: number;
+  seriesCount: number;
+  movieCount: number;
+};
+
+export async function getTotals(userId: string): Promise<Totals> {
+  const [minutes, episodes, movies, completed, byType] = await Promise.all([
+    prisma.watch.aggregate({ where: { userId }, _sum: { minutes: true } }),
+    prisma.watch.count({ where: { userId, episodeId: { not: null } } }),
+    prisma.watch.count({ where: { userId, episodeId: null } }),
+    prisma.libraryEntry.count({ where: { userId, deletedAt: null, status: "COMPLETED" } }),
+    prisma.libraryEntry.groupBy({
+      by: ["titleId"],
+      where: { userId, deletedAt: null },
+      _count: { _all: true },
+    }),
+  ]);
+
+  const typeCounts = await prisma.title.groupBy({
+    by: ["type"],
+    where: { id: { in: byType.map((row) => row.titleId) } },
+    _count: { _all: true },
+  });
+
+  return {
+    minutes: minutes._sum.minutes ?? 0,
+    episodes,
+    movies,
+    titlesCompleted: completed,
+    seriesCount: typeCounts.find((row) => row.type === "SERIES")?._count._all ?? 0,
+    movieCount: typeCounts.find((row) => row.type === "MOVIE")?._count._all ?? 0,
+  };
+}
+
+export type MonthlyPoint = {
+  /** Monatsanfang */
+  month: Date;
+  label: string;
+  episodes: number;
+  movies: number;
+  minutes: number;
+};
+
+/** Aktivität je Monat, lückenlos — auch Monate ohne Sichtung erscheinen. */
+export async function getMonthlyActivity(userId: string, months = 12): Promise<MonthlyPoint[]> {
+  const start = new Date();
+  start.setDate(1);
+  start.setHours(0, 0, 0, 0);
+  start.setMonth(start.getMonth() - (months - 1));
+
+  // Der Monatsschlüssel kommt als Text aus der Datenbank („2026-04").
+  // Ein Zeitstempel würde hier schiefgehen: date_trunc liefert Mitternacht in
+  // der Sitzungszeitzone, JS legt beim Vergleich die lokale Zone an — zwei
+  // Stunden Versatz genügen, damit kein einziger Schlüssel mehr passt.
+  const rows = await prisma.$queryRaw<
+    { month: string; episodes: bigint; movies: bigint; minutes: bigint | null }[]
+  >`
+    SELECT
+      to_char(date_trunc('month', "watchedAt"), 'YYYY-MM') AS month,
+      count(*) FILTER (WHERE "episodeId" IS NOT NULL) AS episodes,
+      count(*) FILTER (WHERE "episodeId" IS NULL) AS movies,
+      sum("minutes") AS minutes
+    FROM "Watch"
+    WHERE "userId" = ${userId} AND "watchedAt" >= ${start}
+    GROUP BY 1
+    ORDER BY 1
+  `;
+
+  const byMonth = new Map(rows.map((row) => [row.month, row]));
+  const points: MonthlyPoint[] = [];
+
+  for (let index = 0; index < months; index += 1) {
+    const month = new Date(start);
+    month.setMonth(start.getMonth() + index);
+    const key = `${month.getFullYear()}-${String(month.getMonth() + 1).padStart(2, "0")}`;
+    const row = byMonth.get(key);
+
+    points.push({
+      month,
+      label: month.toLocaleDateString("de-DE", { month: "short" }),
+      episodes: Number(row?.episodes ?? 0),
+      movies: Number(row?.movies ?? 0),
+      minutes: Number(row?.minutes ?? 0),
+    });
+  }
+
+  return points;
+}
+
+export type Slice = { label: string; minutes: number; count: number; color: string | null };
+
+/**
+ * Verteilung der Schauzeit nach Streamingdienst.
+ * Grundlage ist das Feld „wo schaue ich das" — es sagt, wo tatsächlich
+ * geschaut wurde, nicht bloß, wo es verfügbar wäre.
+ */
+export async function getProviderDistribution(userId: string): Promise<Slice[]> {
+  const rows = await prisma.$queryRaw<{ label: string; minutes: bigint; count: bigint }[]>`
+    SELECT
+      coalesce(nullif(e."whereToWatch", ''), 'Ohne Angabe') AS label,
+      sum(w."minutes") AS minutes,
+      count(*) AS count
+    FROM "Watch" w
+    JOIN "LibraryEntry" e ON e."id" = w."entryId"
+    WHERE w."userId" = ${userId}
+    GROUP BY 1
+    ORDER BY minutes DESC
+  `;
+
+  const providers = await prisma.watchProvider.findMany({ select: { name: true, color: true } });
+  const colorByName = new Map(providers.map((provider) => [provider.name, provider.color]));
+
+  return rows.map((row) => ({
+    label: row.label,
+    minutes: Number(row.minutes ?? 0),
+    count: Number(row.count),
+    color: colorByName.get(row.label) ?? null,
+  }));
+}
+
+/** Verteilung der Schauzeit nach Genre. Mehrfachnennungen zählen mehrfach. */
+export async function getGenreDistribution(userId: string): Promise<Slice[]> {
+  const rows = await prisma.$queryRaw<{ label: string; minutes: bigint; count: bigint }[]>`
+    SELECT
+      genre AS label,
+      sum(w."minutes") AS minutes,
+      count(*) AS count
+    FROM "Watch" w
+    JOIN "Title" t ON t."id" = w."titleId"
+    CROSS JOIN LATERAL unnest(t."genres") AS genre
+    WHERE w."userId" = ${userId}
+    GROUP BY 1
+    ORDER BY minutes DESC
+    LIMIT 12
+  `;
+
+  return rows.map((row) => ({
+    label: row.label,
+    minutes: Number(row.minutes ?? 0),
+    count: Number(row.count),
+    color: null,
+  }));
+}
+
+export type TopTitle = {
+  titleId: string;
+  title: string;
+  posterPath: string | null;
+  rating: number | null;
+  minutes: number;
+  type: "SERIES" | "MOVIE";
+};
+
+/** Bestbewertete Titel. */
+export async function getTopRated(userId: string, limit = 6): Promise<TopTitle[]> {
+  const entries = await prisma.libraryEntry.findMany({
+    where: { userId, deletedAt: null, rating: { not: null } },
+    orderBy: [{ rating: "desc" }, { updatedAt: "desc" }],
+    take: limit,
+    select: {
+      rating: true,
+      title: { select: { id: true, title: true, posterPath: true, type: true } },
+    },
+  });
+
+  return entries.map((entry) => ({
+    titleId: entry.title.id,
+    title: entry.title.title,
+    posterPath: entry.title.posterPath,
+    rating: entry.rating,
+    minutes: 0,
+    type: entry.title.type,
+  }));
+}
+
+/** Titel mit der meisten investierten Zeit. */
+export async function getMostWatched(userId: string, limit = 6): Promise<TopTitle[]> {
+  const rows = await prisma.watch.groupBy({
+    by: ["titleId"],
+    where: { userId },
+    _sum: { minutes: true },
+    orderBy: { _sum: { minutes: "desc" } },
+    take: limit,
+  });
+
+  if (rows.length === 0) return [];
+
+  const titles = await prisma.title.findMany({
+    where: { id: { in: rows.map((row) => row.titleId) } },
+    select: { id: true, title: true, posterPath: true, type: true },
+  });
+  const byId = new Map(titles.map((title) => [title.id, title]));
+
+  return rows.flatMap((row) => {
+    const title = byId.get(row.titleId);
+    return title
+      ? [
+          {
+            titleId: title.id,
+            title: title.title,
+            posterPath: title.posterPath,
+            rating: null,
+            minutes: row._sum.minutes ?? 0,
+            type: title.type,
+          },
+        ]
+      : [];
+  });
+}
+
+export type YearReview = {
+  year: number;
+  minutes: number;
+  episodes: number;
+  movies: number;
+  titlesStarted: number;
+  titlesCompleted: number;
+  busiestMonth: { label: string; minutes: number } | null;
+  topTitle: TopTitle | null;
+};
+
+/** „Das Jahr in Zahlen". */
+export async function getYearReview(userId: string, year: number): Promise<YearReview> {
+  const from = new Date(Date.UTC(year, 0, 1));
+  const to = new Date(Date.UTC(year + 1, 0, 1));
+
+  const [aggregate, episodes, movies, started, completed, months, top] = await Promise.all([
+    prisma.watch.aggregate({
+      where: { userId, watchedAt: { gte: from, lt: to } },
+      _sum: { minutes: true },
+    }),
+    prisma.watch.count({
+      where: { userId, watchedAt: { gte: from, lt: to }, episodeId: { not: null } },
+    }),
+    prisma.watch.count({ where: { userId, watchedAt: { gte: from, lt: to }, episodeId: null } }),
+    prisma.libraryEntry.count({ where: { userId, startedAt: { gte: from, lt: to } } }),
+    prisma.libraryEntry.count({ where: { userId, finishedAt: { gte: from, lt: to } } }),
+    prisma.$queryRaw<{ month: string; minutes: bigint }[]>`
+      SELECT to_char(date_trunc('month', "watchedAt"), 'YYYY-MM') AS month, sum("minutes") AS minutes
+      FROM "Watch"
+      WHERE "userId" = ${userId} AND "watchedAt" >= ${from} AND "watchedAt" < ${to}
+      GROUP BY 1
+      ORDER BY minutes DESC
+      LIMIT 1
+    `,
+    prisma.watch.groupBy({
+      by: ["titleId"],
+      where: { userId, watchedAt: { gte: from, lt: to } },
+      _sum: { minutes: true },
+      orderBy: { _sum: { minutes: "desc" } },
+      take: 1,
+    }),
+  ]);
+
+  const busiest = months[0];
+  const topTitleRow = top[0];
+  const topTitle = topTitleRow
+    ? await prisma.title.findUnique({
+        where: { id: topTitleRow.titleId },
+        select: { id: true, title: true, posterPath: true, type: true },
+      })
+    : null;
+
+  return {
+    year,
+    minutes: aggregate._sum.minutes ?? 0,
+    episodes,
+    movies,
+    titlesStarted: started,
+    titlesCompleted: completed,
+    busiestMonth: busiest
+      ? {
+          label: monthLabel(busiest.month),
+          minutes: Number(busiest.minutes ?? 0),
+        }
+      : null,
+    topTitle:
+      topTitle && topTitleRow
+        ? {
+            titleId: topTitle.id,
+            title: topTitle.title,
+            posterPath: topTitle.posterPath,
+            rating: null,
+            minutes: topTitleRow._sum.minutes ?? 0,
+            type: topTitle.type,
+          }
+        : null,
+  };
+}
+
+/** „2026-04" → „April 2026" */
+function monthLabel(key: string): string {
+  const [year, month] = key.split("-").map(Number);
+  if (!year || !month) return key;
+  return new Date(year, month - 1, 1).toLocaleDateString("de-DE", {
+    month: "long",
+    year: "numeric",
+  });
+}
+
+/** Jahre, in denen überhaupt etwas gesehen wurde — für die Jahresauswahl. */
+export async function getActiveYears(userId: string): Promise<number[]> {
+  const rows = await prisma.$queryRaw<{ year: number }[]>`
+    SELECT DISTINCT extract(year FROM "watchedAt")::int AS year
+    FROM "Watch"
+    WHERE "userId" = ${userId}
+    ORDER BY year DESC
+  `;
+  return rows.map((row) => row.year);
+}