/**
 * The playlist routes. `:playlistId` takes an id or a slug.
 *
 * - `GET /api/playlists/by-dump/:dumpId/memberships` — signed in. Answers each
 *   of the caller's playlists and whether it holds the dump.
 * - `POST /api/playlists` — signed in. Creates a playlist.
 * - `GET /api/playlists/:playlistId` — optional sign-in. Answers a playlist
 *   with the dumps the caller may see in it; a private one only to its owner.
 * - `PUT /api/playlists/:playlistId` — signed in, as its owner or with
 *   `playlist:moderate`. Updates its title, description and visibility.
 * - `DELETE /api/playlists/:playlistId` — signed in, as its owner or with
 *   `playlist:moderate`. Deletes it.
 * - `POST /api/playlists/:playlistId/dumps/:dumpId` — signed in, as its owner
 *   or with `playlist:moderate`. Adds a dump at the top.
 * - `DELETE /api/playlists/:playlistId/dumps/:dumpId` — signed in, as its owner
 *   or with `playlist:moderate`. Removes a dump.
 * - `POST /api/playlists/:playlistId/image` — signed in, as its owner or with
 *   `playlist:moderate`. Replaces its cover (multipart `file`, at most 5 MB).
 * - `GET /api/playlists/:playlistId/image?token=` — public; a private
 *   playlist's cover needs its owner's media `token`. Serves its cover; 404
 *   without one.
 * - `PUT /api/playlists/:playlistId/order` — signed in, as its owner or with
 *   `playlist:moderate`. Reorders the dumps the caller can see in it.
 *
 * @module
 */

import { Router } from "@oak/oak";
import { authenticateMedia, parseOptionalAuth } from "../lib/auth.ts";
import { APIErrorCode, type APIResponse } from "../../shared/api.ts";
import { APIException } from "../lib/api-exception.ts";
import {
  isCreatePlaylistRequest,
  isReorderPlaylistRequest,
  isUpdatePlaylistRequest,
} from "../validators/playlist.ts";
import type {
  Playlist,
  PlaylistMembership,
  PlaylistWithDumps,
} from "../../shared/playlist.ts";
import { authMiddleware, type AuthState } from "../middleware/auth.ts";
import { can } from "../lib/permissions.ts";
import {
  addDumpToPlaylist,
  createPlaylist,
  deletePlaylist,
  getEditablePlaylist,
  getPlaylist,
  getPlaylistImageInfo,
  getPlaylistMembershipsForDump,
  removeDumpFromPlaylist,
  reorderPlaylist,
  setPlaylistImage,
  updatePlaylist,
} from "../services/playlist-service.ts";
import {
  PLAYLIST_IMAGES_DIR,
  serveUploadedFile,
  validateImageUpload,
} from "../lib/upload.ts";

/** The router serving the endpoints the module doc lists. */
const router: Router<AuthState> = new Router<AuthState>({
  prefix: "/api/playlists",
});

// Before /:playlistId, which would otherwise match "by-dump".
router.get("/by-dump/:dumpId/memberships", authMiddleware, (ctx) => {
  const { dumpId } = ctx.params;
  const userId = ctx.state.user.userId;
  const responseBody: APIResponse<PlaylistMembership[]> = {
    success: true,
    data: getPlaylistMembershipsForDump(dumpId, userId),
  };
  ctx.response.body = responseBody;
});

router.post("/", authMiddleware, async (ctx) => {
  const body: unknown = await ctx.request.body.json();
  if (!isCreatePlaylistRequest(body)) {
    throw new APIException(
      APIErrorCode.VALIDATION_ERROR,
      400,
      "Invalid request",
    );
  }
  const responseBody: APIResponse<Playlist> = {
    success: true,
    data: createPlaylist(body, ctx.state.user.userId),
  };
  ctx.response.status = 201;
  ctx.response.body = responseBody;
});

router.get("/:playlistId", async (ctx) => {
  const requestingUserId = await parseOptionalAuth(ctx);
  const responseBody: APIResponse<PlaylistWithDumps> = {
    success: true,
    data: getPlaylist(ctx.params.playlistId, requestingUserId),
  };
  ctx.response.body = responseBody;
});

router.put("/:playlistId", authMiddleware, async (ctx) => {
  const body: unknown = await ctx.request.body.json();
  if (!isUpdatePlaylistRequest(body)) {
    throw new APIException(
      APIErrorCode.VALIDATION_ERROR,
      400,
      "Invalid request",
    );
  }
  const playlist = updatePlaylist(
    ctx.params.playlistId,
    body,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  const responseBody: APIResponse<Playlist> = { success: true, data: playlist };
  ctx.response.body = responseBody;
});

router.delete("/:playlistId", authMiddleware, (ctx) => {
  deletePlaylist(
    ctx.params.playlistId,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  ctx.response.status = 204;
});

router.post("/:playlistId/dumps/:dumpId", authMiddleware, (ctx) => {
  addDumpToPlaylist(
    ctx.params.playlistId,
    ctx.params.dumpId,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  ctx.response.status = 204;
});

router.delete("/:playlistId/dumps/:dumpId", authMiddleware, (ctx) => {
  removeDumpFromPlaylist(
    ctx.params.playlistId,
    ctx.params.dumpId,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  ctx.response.status = 204;
});

router.post("/:playlistId/image", authMiddleware, async (ctx) => {
  const contentType = ctx.request.headers.get("content-type") ?? "";
  if (!contentType.includes("multipart/form-data")) {
    throw new APIException(
      APIErrorCode.BAD_REQUEST,
      400,
      "Expected multipart/form-data",
    );
  }

  const body = await ctx.request.body.formData();
  const file = body.get("file");

  if (!(file instanceof File)) {
    throw new APIException(APIErrorCode.BAD_REQUEST, 400, "Missing file field");
  }

  const data = new Uint8Array(await file.arrayBuffer());
  const mime = validateImageUpload(data);

  // The file goes in before the row changes. Setting image_mime and bumping
  // updated_at announces the cover (the `?v=` on its URL, the socket event),
  // so the bytes must already be there: an earlier fetch would cache the old
  // cover under the new URL, and a failed write would leave a cover that 404s.
  // Written beside and renamed over, so the old cover is never half-replaced.
  const { id } = getEditablePlaylist(
    ctx.params.playlistId,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  const filePath = `${PLAYLIST_IMAGES_DIR}/${id}`;
  const tmpPath = `${filePath}.${crypto.randomUUID()}.tmp`;
  await Deno.mkdir(PLAYLIST_IMAGES_DIR, { recursive: true });
  try {
    await Deno.writeFile(tmpPath, data);
    await Deno.rename(tmpPath, filePath);
  } catch (err) {
    await Deno.remove(tmpPath).catch(() => {});
    throw err;
  }
  const playlist = setPlaylistImage(
    id,
    mime,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  const responseBody: APIResponse<Playlist> = { success: true, data: playlist };
  ctx.response.body = responseBody;
});

router.get("/:playlistId/image", async (ctx) => {
  // An <img> can't send an Authorization header, so a private playlist's owner
  // is known by the media token in the query string, as for dump files.
  const token = ctx.request.url.searchParams.get("token");
  const viewerId = token ? await authenticateMedia(token) : null;
  const info = getPlaylistImageInfo(ctx.params.playlistId, viewerId);
  if (!info) {
    ctx.response.status = 404;
    return;
  }
  // The URL may carry a media token; keep it out of anyone else's logs.
  ctx.response.headers.set("Referrer-Policy", "no-referrer");
  await serveUploadedFile(
    ctx,
    `${PLAYLIST_IMAGES_DIR}/${info.id}`,
    info.imageMime,
    3600,
    !info.isPublic,
  );
});

router.put("/:playlistId/order", authMiddleware, async (ctx) => {
  const body: unknown = await ctx.request.body.json();
  if (!isReorderPlaylistRequest(body)) {
    throw new APIException(
      APIErrorCode.VALIDATION_ERROR,
      400,
      "Invalid request",
    );
  }
  reorderPlaylist(
    ctx.params.playlistId,
    body.dumpIds,
    ctx.state.user.userId,
    can(ctx.state.user, "playlist:moderate"),
  );
  const responseBody: APIResponse<null> = { success: true, data: null };
  ctx.response.body = responseBody;
});

export default router;