import type { MediaCollection, MediaCollectionKind, MediaLabelSource } from "@rakazo/contracts";
import { roundCoordinate } from "@rakazo/media";
import type { MediaCollection as MediaCollectionRow, PrismaClient } from "./client.js";
import { Prisma } from "./client.js";
import type { CollectionStats, MediaDb, MediaPage, MediaPageInput } from "./media-shared.js";
import {
  assertAssetsInSpace,
  decodeKeysetCursor,
  EMPTY_COLLECTION_STATS,
  InvalidMediaInputError,
  keysetAfterSql,
  lockMediaKey,
  mapMediaAsset,
  mapMediaCollection,
  pageLimit,
  toPage,
} from "./media-shared.js";
import { IsolationError } from "./scope.js";

/** One session or theme cluster computed by the worker. */
export interface MediaClusterInput {
  /** Stable key so a re-run updates the same collection. */
  key: string;
  title: string;
  labelSource: Exclude<MediaLabelSource, "user">;
  startAt: Date | null;
  endAt: Date | null;
  centroid: { lat: number; lon: number } | null;
  coverAssetId: string | null;
  /** In display order. */
  assetIds: string[];
}

export interface ReplaceClustersResult {
  created: number;
  updated: number;
  deleted: number;
}

async function collectionStats(db: MediaDb, ids: string[]): Promise<Map<string, CollectionStats>> {
  if (ids.length === 0) return new Map();
  const rows = await db.$queryRaw<
    Array<{ id: string; assetCount: number; videoCount: number; totalDurationMs: bigint }>
  >(Prisma.sql`
    SELECT ci."collectionId" AS id,
      count(*)::int AS "assetCount",
      (count(*) FILTER (WHERE a.kind = 'video'))::int AS "videoCount",
      coalesce(sum(a."durationMs"), 0)::bigint AS "totalDurationMs"
    FROM media_collection_items ci
    JOIN media_assets a ON a.id = ci."assetId"
    WHERE ci."collectionId" IN (${Prisma.join(ids)})
    GROUP BY ci."collectionId"
  `);
  return new Map(
    rows.map((row) => [
      row.id,
      {
        assetCount: row.assetCount,
        videoCount: row.videoCount,
        totalDurationMs: Number(row.totalDurationMs),
      },
    ]),
  );
}

async function collectionDto(db: MediaDb, row: MediaCollectionRow): Promise<MediaCollection> {
  const stats = await collectionStats(db, [row.id]);
  return mapMediaCollection(row, stats.get(row.id) ?? EMPTY_COLLECTION_STATS);
}

/** Assets ordered by capture time, undated last, with the span they cover. */
async function orderedAssets(db: MediaDb, spaceId: string, assetIds: string[]) {
  const assets = await db.mediaAsset.findMany({
    where: { spaceId, id: { in: [...new Set(assetIds)] } },
    orderBy: [{ capturedAt: { sort: "asc", nulls: "last" } }, { id: "asc" }],
    select: { id: true, capturedAt: true },
  });
  const dated = assets.flatMap((asset) => (asset.capturedAt ? [asset.capturedAt] : []));
  return {
    ids: assets.map((asset) => asset.id),
    startAt: dated[0] ?? null,
    endAt: dated.at(-1) ?? null,
  };
}

async function writeItems(db: MediaDb, collectionId: string, assetIds: string[]): Promise<void> {
  await db.mediaCollectionItem.deleteMany({ where: { collectionId } });
  if (assetIds.length === 0) return;
  await db.mediaCollectionItem.createMany({
    data: [...new Set(assetIds)].map((assetId, position) => ({ collectionId, assetId, position })),
  });
}

/** Sessions, themes and manual collections. */
export function createMediaCollectionRepos(prisma: PrismaClient) {
  // -------------------------------------------------------------------------
  // Collections
  // -------------------------------------------------------------------------

  async function requireCollection(db: MediaDb, spaceId: string, collectionId: string) {
    const row = await db.mediaCollection.findFirst({ where: { id: collectionId, spaceId } });
    if (!row) throw new IsolationError();
    return row;
  }

  /**
   * Apply a full clustering run for one kind. Collections are matched by cluster key;
   * a title the user set survives, stale rule/model clusters are removed, and manual
   * collections are never touched.
   */
  async function replaceClusters(
    spaceId: string,
    kind: Exclude<MediaCollectionKind, "manual">,
    clusters: MediaClusterInput[],
  ): Promise<ReplaceClustersResult> {
    const keys = new Set<string>();
    for (const cluster of clusters) {
      if (keys.has(cluster.key)) throw new InvalidMediaInputError("Duplicate cluster key");
      keys.add(cluster.key);
      if (cluster.coverAssetId && !cluster.assetIds.includes(cluster.coverAssetId)) {
        throw new InvalidMediaInputError("Cover asset is not in its cluster");
      }
    }
    return prisma.$transaction(
      async (tx) => {
        await lockMediaKey(tx, `clusters:${spaceId}:${kind}`);
        await assertAssetsInSpace(
          tx,
          spaceId,
          clusters.flatMap((cluster) => cluster.assetIds),
        );
        const existing = await tx.mediaCollection.findMany({
          where: { spaceId, kind, clusterKey: { not: null } },
        });
        const byKey = new Map(existing.map((row) => [row.clusterKey as string, row]));
        const result: ReplaceClustersResult = { created: 0, updated: 0, deleted: 0 };
        for (const cluster of clusters) {
          const fields = {
            startAt: cluster.startAt,
            endAt: cluster.endAt,
            centroidLat: cluster.centroid ? roundCoordinate(cluster.centroid.lat) : null,
            centroidLon: cluster.centroid ? roundCoordinate(cluster.centroid.lon) : null,
            coverAssetId: cluster.coverAssetId,
          };
          const current = byKey.get(cluster.key);
          let collectionId: string;
          if (current) {
            const keepTitle = current.labelSource === "user";
            await tx.mediaCollection.update({
              where: { id: current.id },
              data: {
                ...fields,
                ...(keepTitle ? {} : { title: cluster.title, labelSource: cluster.labelSource }),
              },
            });
            collectionId = current.id;
            result.updated += 1;
          } else {
            const created = await tx.mediaCollection.create({
              data: {
                ...fields,
                spaceId,
                kind,
                clusterKey: cluster.key,
                title: cluster.title,
                labelSource: cluster.labelSource,
              },
              select: { id: true },
            });
            collectionId = created.id;
            result.created += 1;
          }
          await writeItems(tx, collectionId, cluster.assetIds);
        }
        const stale = existing.filter(
          (row) => !keys.has(row.clusterKey as string) && row.labelSource !== "user",
        );
        if (stale.length > 0) {
          const deleted = await tx.mediaCollection.deleteMany({
            where: { spaceId, id: { in: stale.map((row) => row.id) } },
          });
          result.deleted = deleted.count;
        }
        return result;
      },
      { timeout: 120_000 },
    );
  }

  async function listCollections(
    spaceId: string,
    input: MediaPageInput & { kind?: MediaCollectionKind },
  ): Promise<MediaPage<MediaCollection>> {
    const limit = pageLimit(input.limit);
    const cursor = input.cursor ? decodeKeysetCursor(input.cursor) : null;
    const keys = await prisma.$queryRaw<Array<{ id: string }>>(Prisma.sql`
      SELECT c.id FROM media_collections c
      WHERE c."spaceId" = ${spaceId}
        ${input.kind ? Prisma.sql`AND c.kind = ${input.kind}` : Prisma.empty}
        AND ${keysetAfterSql(cursor, Prisma.sql`c."startAt"`, Prisma.sql`c.id`)}
      ORDER BY c."startAt" DESC NULLS LAST, c.id DESC
      LIMIT ${limit + 1}
    `);
    const ids = keys.map((key) => key.id);
    const [rows, stats] = await Promise.all([
      prisma.mediaCollection.findMany({ where: { spaceId, id: { in: ids } } }),
      collectionStats(prisma, ids),
    ]);
    const byId = new Map(rows.map((row) => [row.id, row]));
    const ordered = ids.flatMap((id) => {
      const row = byId.get(id);
      return row ? [row] : [];
    });
    return toPage(
      ordered,
      limit,
      (row) => ({ at: row.startAt, id: row.id }),
      (row) => mapMediaCollection(row, stats.get(row.id) ?? EMPTY_COLLECTION_STATS),
    );
  }

  async function getCollection(spaceId: string, collectionId: string) {
    const row = await requireCollection(prisma, spaceId, collectionId);
    const items = await prisma.mediaCollectionItem.findMany({
      where: { collectionId, asset: { spaceId } },
      orderBy: [{ position: "asc" }, { assetId: "asc" }],
      include: { asset: true },
    });
    return {
      collection: await collectionDto(prisma, row),
      assets: items.map((item) => mapMediaAsset(item.asset)),
    };
  }

  /** Asset ids of a collection in display order. */
  async function collectionAssetIds(spaceId: string, collectionIds: string[]): Promise<string[]> {
    const ids = [...new Set(collectionIds)];
    if (ids.length === 0) return [];
    const owned = await prisma.mediaCollection.count({ where: { spaceId, id: { in: ids } } });
    if (owned !== ids.length) throw new IsolationError();
    const items = await prisma.mediaCollectionItem.findMany({
      where: { collectionId: { in: ids } },
      orderBy: [{ position: "asc" }, { assetId: "asc" }],
      select: { assetId: true, collectionId: true },
    });
    const order = new Map(ids.map((id, index) => [id, index]));
    items.sort((a, b) => (order.get(a.collectionId) ?? 0) - (order.get(b.collectionId) ?? 0));
    return [...new Set(items.map((item) => item.assetId))];
  }

  /** The user's title wins over every later clustering label. */
  async function renameCollection(
    spaceId: string,
    collectionId: string,
    title: string,
  ): Promise<MediaCollection> {
    const result = await prisma.mediaCollection.updateMany({
      where: { id: collectionId, spaceId },
      data: { title, labelSource: "user" },
    });
    if (result.count !== 1) throw new IsolationError();
    return collectionDto(prisma, await requireCollection(prisma, spaceId, collectionId));
  }

  /** Merge into the first collection; the others are deleted. */
  async function mergeCollections(
    spaceId: string,
    collectionIds: string[],
  ): Promise<MediaCollection> {
    const ids = [...new Set(collectionIds)];
    if (ids.length < 2) throw new InvalidMediaInputError("Merge needs two collections");
    return prisma.$transaction(async (tx) => {
      const rows = await tx.mediaCollection.findMany({ where: { spaceId, id: { in: ids } } });
      if (rows.length !== ids.length) throw new IsolationError();
      const target = rows.find((row) => row.id === ids[0]) as MediaCollectionRow;
      const items = await tx.mediaCollectionItem.findMany({
        where: { collectionId: { in: ids } },
        select: { assetId: true },
      });
      const assets = await orderedAssets(
        tx,
        spaceId,
        items.map((item) => item.assetId),
      );
      await writeItems(tx, target.id, assets.ids);
      await tx.mediaCollection.deleteMany({
        where: { spaceId, id: { in: ids.filter((id) => id !== target.id) } },
      });
      const updated = await tx.mediaCollection.update({
        where: { id: target.id },
        data: {
          startAt: assets.startAt,
          endAt: assets.endAt,
          labelSource: "user",
          coverAssetId: target.coverAssetId ?? assets.ids[0] ?? null,
        },
      });
      return collectionDto(tx, updated);
    });
  }

  /** Split before `atAssetId`: it and every later asset move to a new collection. */
  async function splitCollection(
    spaceId: string,
    collectionId: string,
    atAssetId: string,
  ): Promise<MediaCollection[]> {
    return prisma.$transaction(async (tx) => {
      const row = await requireCollection(tx, spaceId, collectionId);
      const items = await tx.mediaCollectionItem.findMany({
        where: { collectionId },
        orderBy: [{ position: "asc" }, { assetId: "asc" }],
        select: { assetId: true },
      });
      const index = items.findIndex((item) => item.assetId === atAssetId);
      if (index <= 0) throw new InvalidMediaInputError("Split asset must be inside the collection");
      const first = await orderedAssets(
        tx,
        spaceId,
        items.slice(0, index).map((item) => item.assetId),
      );
      const second = await orderedAssets(
        tx,
        spaceId,
        items.slice(index).map((item) => item.assetId),
      );
      await writeItems(tx, collectionId, first.ids);
      const kept = await tx.mediaCollection.update({
        where: { id: collectionId },
        data: {
          startAt: first.startAt,
          endAt: first.endAt,
          labelSource: "user",
          coverAssetId:
            row.coverAssetId && first.ids.includes(row.coverAssetId)
              ? row.coverAssetId
              : (first.ids[0] ?? null),
        },
      });
      const created = await tx.mediaCollection.create({
        data: {
          spaceId,
          kind: row.kind,
          title: `${row.title} (2)`,
          labelSource: "user",
          startAt: second.startAt,
          endAt: second.endAt,
          centroidLat: row.centroidLat,
          centroidLon: row.centroidLon,
          coverAssetId:
            row.coverAssetId && second.ids.includes(row.coverAssetId)
              ? row.coverAssetId
              : (second.ids[0] ?? null),
        },
      });
      await writeItems(tx, created.id, second.ids);
      return [await collectionDto(tx, kept), await collectionDto(tx, created)];
    });
  }

  async function createManualCollection(
    spaceId: string,
    title: string,
    assetIds: string[],
  ): Promise<MediaCollection> {
    return prisma.$transaction(async (tx) => {
      await assertAssetsInSpace(tx, spaceId, assetIds);
      const assets = await orderedAssets(tx, spaceId, assetIds);
      const created = await tx.mediaCollection.create({
        data: {
          spaceId,
          kind: "manual",
          title,
          labelSource: "user",
          startAt: assets.startAt,
          endAt: assets.endAt,
          coverAssetId: assets.ids[0] ?? null,
        },
      });
      await writeItems(tx, created.id, assets.ids);
      return collectionDto(tx, created);
    });
  }

  return {
    replaceClusters,
    listCollections,
    getCollection,
    collectionAssetIds,
    renameCollection,
    mergeCollections,
    splitCollection,
    createManualCollection,
  };
}