import type { SQLOutputValue } from "node:sqlite";
import {
  APIErrorCode,
  APIException,
  type CreatePlaylistRequest,
  type Dump,
  type Playlist,
  type PlaylistMembership,
  type PlaylistWithDumps,
  type UpdatePlaylistRequest,
} from "../model/interfaces.ts";
import {
  db,
  dumpRowToApi,
  isDumpRow,
  isPlaylistRow,
  playlistRowToApi,
} from "../model/db.ts";
import {
  broadcastPlaylistCreated,
  broadcastPlaylistDeleted,
  broadcastPlaylistDumpsUpdated,
  broadcastPlaylistUpdated,
} from "./ws-service.ts";
import {
  notifyMentions,
  notifyPlaylistFollowersNewDump,
} from "./notification-service.ts";
import { makeSlug, UUID_RE } from "../lib/slugify.ts";

const DUMP_SELECT_COLS =
  "id, kind, title, slug, comment, user_id, created_at, url, rich_content, file_name, file_mime, file_size, vote_count, is_private";

const PLAYLIST_SELECT = `p.*, u.username as owner_username,
   (SELECT COUNT(*) FROM playlist_dumps pd WHERE pd.playlist_id = p.id) as dump_count
   FROM playlists p LEFT JOIN users u ON u.id = p.user_id`;

function getPlaylistById(idOrSlug: string): Playlist {
  const row = UUID_RE.test(idOrSlug)
    ? db.prepare(`SELECT ${PLAYLIST_SELECT} WHERE p.id = ?;`).get(idOrSlug)
    : db.prepare(`SELECT ${PLAYLIST_SELECT} WHERE p.slug = ?;`).get(idOrSlug);
  if (!row || !isPlaylistRow(row)) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "Playlist not found");
  }
  return playlistRowToApi(row);
}

export function createPlaylist(
  req: CreatePlaylistRequest,
  userId: string,
): Playlist {
  const id = crypto.randomUUID();
  const createdAt = new Date();
  const slug = makeSlug(req.title, id);
  db.prepare(
    `INSERT INTO playlists (id, user_id, title, slug, description, is_public, created_at)
     VALUES (?, ?, ?, ?, ?, ?, ?);`,
  ).run(
    id,
    userId,
    req.title,
    slug,
    req.description ?? null,
    req.isPublic ? 1 : 0,
    createdAt.toISOString(),
  );
  const playlist: Playlist = {
    id,
    userId,
    title: req.title,
    slug,
    description: req.description,
    isPublic: req.isPublic,
    createdAt,
  };
  if (req.description) {
    notifyMentions(userId, req.description, "playlist", id, req.title);
  }
  broadcastPlaylistCreated(playlist);
  return playlist;
}

export function getPlaylist(
  playlistId: string,
  requestingUserId: string | null,
): PlaylistWithDumps {
  const playlist = getPlaylistById(playlistId);

  if (!playlist.isPublic && requestingUserId !== playlist.userId) {
    throw new APIException(APIErrorCode.NOT_FOUND, 404, "Playlist not found");
  }

  const dumpCols = DUMP_SELECT_COLS.split(", ").map((c) => `d.${c}`).join(", ");
  const isOwner = requestingUserId === playlist.userId;

  // For public playlists (or when viewed by non-owner), filter out private dumps
  const rows = db.prepare(
    `SELECT ${dumpCols},
       (SELECT COUNT(*) FROM comments WHERE dump_id = d.id AND deleted = 0) as comment_count
     FROM dumps d
     INNER JOIN playlist_dumps pd ON d.id = pd.dump_id
     WHERE pd.playlist_id = ?
       AND (d.is_private = 0 OR d.user_id = ?)
     ORDER BY pd.position ASC;`,
  ).all(playlist.id, requestingUserId ?? "");

  const dumps: Dump[] = rows.filter(isDumpRow).map(dumpRowToApi);
  // Owners always see their own private dumps; strip them for non-owners regardless
  const visibleDumps = isOwner ? dumps : dumps.filter((d) => !d.isPrivate);

  return { ...playlist, dumps: visibleDumps };
}

export function listPlaylistsByUser(
  userId: string,
  requestingUserId: string | null,
  page: number,
  limit: number,
): { items: Playlist[]; total: number } {
  const isOwner = requestingUserId === userId;
  const offset = (page - 1) * limit;

  const countSql = isOwner
    ? `SELECT COUNT(*) as count FROM playlists WHERE user_id = ?;`
    : `SELECT COUNT(*) as count FROM playlists WHERE user_id = ? AND is_public = 1;`;
  const sql = isOwner
    ? `SELECT ${PLAYLIST_SELECT} WHERE p.user_id = ? ORDER BY p.created_at DESC LIMIT ? OFFSET ?;`
    : `SELECT ${PLAYLIST_SELECT} WHERE p.user_id = ? AND p.is_public = 1 ORDER BY p.created_at DESC LIMIT ? OFFSET ?;`;

  const totalRow = db.prepare(countSql).get(userId) as
    | { count: number }
    | undefined;
  const rows = db.prepare(sql).all(userId, limit, offset);
  return {
    items: rows.filter(isPlaylistRow).map(playlistRowToApi),
    total: totalRow?.count ?? 0,
  };
}

export function updatePlaylist(
  playlistId: string,
  req: UpdatePlaylistRequest,
  requestingUserId: string,
): Playlist {
  const playlist = getPlaylistById(playlistId);

  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }

  const newTitle = req.title ?? playlist.title;
  const newDescription = "description" in req
    ? (req.description ?? null)
    : (playlist.description ?? null);
  const newIsPublic = req.isPublic !== undefined
    ? req.isPublic
    : playlist.isPublic;

  const now = new Date();
  const newSlug = makeSlug(newTitle, playlist.id);
  db.prepare(
    `UPDATE playlists SET title = ?, slug = ?, description = ?, is_public = ?, updated_at = ? WHERE id = ?;`,
  ).run(
    newTitle,
    newSlug,
    newDescription,
    newIsPublic ? 1 : 0,
    now.toISOString(),
    playlist.id,
  );

  const updated: Playlist = {
    ...playlist,
    title: newTitle,
    slug: newSlug,
    description: newDescription ?? undefined,
    isPublic: newIsPublic,
    updatedAt: now,
  };
  if (newDescription) {
    notifyMentions(
      requestingUserId,
      newDescription,
      "playlist",
      playlist.id,
      newTitle,
    );
  }
  broadcastPlaylistUpdated(updated);
  return updated;
}

export function deletePlaylist(
  playlistId: string,
  requestingUserId: string,
): void {
  const playlist = getPlaylistById(playlistId);

  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }

  db.prepare(`DELETE FROM playlists WHERE id = ?;`).run(playlist.id);
  broadcastPlaylistDeleted(playlist.id, playlist.userId, playlist.isPublic);
}

export function setPlaylistImage(
  playlistId: string,
  imageMime: string,
  requestingUserId: string,
): Playlist {
  const playlist = getPlaylistById(playlistId);
  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }
  db.prepare(`UPDATE playlists SET image_mime = ? WHERE id = ?;`).run(
    imageMime,
    playlist.id,
  );
  const updated = getPlaylistById(playlist.id);
  broadcastPlaylistUpdated(updated);
  return updated;
}

export function addDumpToPlaylist(
  playlistId: string,
  dumpId: string,
  requestingUserId: string,
): void {
  const playlist = getPlaylistById(playlistId);

  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }

  const minRow = db.prepare(
    `SELECT MIN(position) as min_pos FROM playlist_dumps WHERE playlist_id = ?;`,
  ).get(playlist.id) as { min_pos: number | null } | undefined;

  const nextPos = (minRow?.min_pos ?? 1) - 1;
  const addedAt = new Date().toISOString();

  try {
    db.prepare(
      `INSERT INTO playlist_dumps (playlist_id, dump_id, position, added_at)
       VALUES (?, ?, ?, ?);`,
    ).run(playlist.id, dumpId, nextPos, addedAt);
  } catch (err) {
    const msg = err instanceof Error ? err.message : String(err);
    if (msg.includes("UNIQUE") || msg.includes("unique")) {
      throw new APIException(
        APIErrorCode.VALIDATION_ERROR,
        409,
        "Dump already in playlist",
      );
    }
    throw err;
  }

  const dumpIds = getCurrentDumpIds(playlist.id);
  broadcastPlaylistDumpsUpdated(playlist, dumpIds);

  if (playlist.isPublic) {
    const dumpRow = db.prepare(`SELECT title FROM dumps WHERE id = ?;`).get(
      dumpId,
    ) as { title: string } | undefined;
    if (dumpRow) {
      notifyPlaylistFollowersNewDump(
        playlist.id,
        playlist.title,
        dumpId,
        dumpRow.title,
      );
    }
  }
}

export function removeDumpFromPlaylist(
  playlistId: string,
  dumpId: string,
  requestingUserId: string,
): void {
  const playlist = getPlaylistById(playlistId);

  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }

  db.prepare(
    `DELETE FROM playlist_dumps WHERE playlist_id = ? AND dump_id = ?;`,
  ).run(playlist.id, dumpId);

  const dumpIds = getCurrentDumpIds(playlist.id);
  broadcastPlaylistDumpsUpdated(playlist, dumpIds);
}

export function reorderPlaylist(
  playlistId: string,
  dumpIds: string[],
  requestingUserId: string,
): void {
  const playlist = getPlaylistById(playlistId);

  if (playlist.userId !== requestingUserId) {
    throw new APIException(APIErrorCode.UNAUTHORIZED, 403, "Forbidden");
  }

  const currentIds = getCurrentDumpIds(playlist.id);
  const currentSet = new Set(currentIds);
  const newSet = new Set(dumpIds);

  if (
    currentSet.size !== newSet.size ||
    !currentIds.every((id) => newSet.has(id))
  ) {
    throw new APIException(
      APIErrorCode.BAD_REQUEST,
      400,
      "dumpIds must match current playlist members exactly",
    );
  }

  const update = db.prepare(
    `UPDATE playlist_dumps SET position = ? WHERE playlist_id = ? AND dump_id = ?;`,
  );
  for (let i = 0; i < dumpIds.length; i++) {
    update.run(i, playlist.id, dumpIds[i]);
  }

  broadcastPlaylistDumpsUpdated(playlist, dumpIds);
}

export function getPlaylistMembershipsForDump(
  dumpId: string,
  userId: string,
): PlaylistMembership[] {
  const rows = db.prepare(
    `SELECT p.*, pd.dump_id IS NOT NULL as has_dump
     FROM playlists p
     LEFT JOIN playlist_dumps pd ON pd.playlist_id = p.id AND pd.dump_id = ?
     WHERE p.user_id = ?
     ORDER BY p.created_at DESC;`,
  ).all(dumpId, userId) as Array<Record<string, SQLOutputValue>>;

  return rows.map((row) => {
    if (!isPlaylistRow(row)) {
      throw new APIException(
        APIErrorCode.SERVER_ERROR,
        500,
        "Malformed playlist data",
      );
    }
    return {
      playlist: playlistRowToApi(row),
      hasDump: Boolean(row.has_dump),
    };
  });
}

export function getPlaylistImageInfo(
  idOrSlug: string,
): { id: string; imageMime: string } | undefined {
  const playlist = getPlaylistById(idOrSlug);
  return playlist.imageMime
    ? { id: playlist.id, imageMime: playlist.imageMime }
    : undefined;
}

function getCurrentDumpIds(playlistId: string): string[] {
  const rows = db.prepare(
    `SELECT dump_id FROM playlist_dumps WHERE playlist_id = ? ORDER BY position ASC;`,
  ).all(playlistId) as Array<{ dump_id: string }>;
  return rows.map((r) => r.dump_id);
}