watchparty/server/src/index.ts

'use strict';

import path from 'path';
import http from 'http';
import express, { type NextFunction, type Request, type Response } from 'express';
import { Server as SocketIoServer } from 'socket.io';

import { EMBY_SERVER_URL, PORT } from './config';
import { Logger } from './Logger';
import { AuthService, SESSION_COOKIE, SESSION_TTL_MS } from './services/AuthService';
import { CatalogService, CatalogFetchError, splitPlaylistByMediaType } from './services/CatalogService';
import { PartyService } from './services/PartyService';
import { MusicQueueService } from './services/MusicQueueService';
import { TranscodeService } from './services/TranscodeService';
import { PartyStreamService } from './services/PartyStreamService';
import { PlaystateService } from './services/PlaystateService';
import { SocketGateway } from './realtime/SocketGateway';
import type { ClientToServerEvents, EmbySession, MediaType, QueueItem, ServerToClientEvents } from './types';

const app = express();
app.set('trust proxy', 1); // behind openresty/nginx - needed for req.secure to reflect the real scheme
app.use(express.json());

// Everything the browser needs - the app shell AND every Emby call - is
// same-origin from here on. See docs/architecture.md for why: the previous
// version had the browser call Emby directly and hit real CORS problems.
// client/dist is esbuild's output (client/src compiled) - see
// client/build.mjs and docs/architecture.md's TypeScript-migration section.
app.use(express.static(path.join(__dirname, '..', '..', 'client', 'dist')));

function requireSession(req: Request, res: Response, next: NextFunction): void {
  const session = AuthService.sessionFromRequest(req);
  if (!session) {
    res.status(401).json({ error: 'Session expirée, reconnecte-toi.' });
    return;
  }
  req.embySession = session;
  next();
}

/**
 * Express 4 doesn't catch a rejected Promise from an async route handler
 * on its own - an unhandled rejection there would either crash the
 * process or just hang the request forever, depending on Node version.
 * Every route below is wrapped in this so a service throwing
 * (CatalogFetchError, a raw network failure, anything) always turns into
 * a real HTTP response instead - see the error-handling middleware at the
 * bottom of this file for where it actually gets turned into one.
 */
function asyncRoute(handler: (req: Request, res: Response) => Promise<void>) {
  return (req: Request, res: Response, next: NextFunction) => {
    handler(req, res).catch(next);
  };
}

/**
 * Reads a required `:name` route param. A matched Express route always has
 * one (Express itself guarantees it; none of these routes use an optional
 * `:name?` segment) - this just gives TypeScript the same certainty:
 * `req.params` is an index-signature type, so `noUncheckedIndexedAccess`
 * (tsconfig.json) sees every access as possibly-`undefined` on its own.
 */
function param(req: Request, name: string): string {
  return req.params[name] as string;
}

// --- Auth ----------------------------------------------------------------
// The browser only ever sends a username/password once, to us. From then on
// it holds an opaque session cookie - never Emby's own access token.

app.post('/api/auth/login', asyncRoute(async (req, res) => {
  const { username, password } = req.body || {};
  if (!username || !password) {
    res.status(400).json({ error: "Nom d'utilisateur et mot de passe requis." });
    return;
  }

  const sessionId = await AuthService.login(username, password);
  if (!sessionId) {
    res.status(401).json({ error: 'Identifiants refusés.' });
    return;
  }

  res.cookie(SESSION_COOKIE, sessionId, {
    httpOnly: true,
    sameSite: 'lax',
    secure: req.secure,
    maxAge: SESSION_TTL_MS
  });
  res.json({ userName: AuthService.getSession(sessionId)!.userName });
}));

app.post('/api/auth/logout', (req, res) => {
  const cookies = AuthService.parseCookies(req.headers.cookie);
  if (cookies[SESSION_COOKIE]) {
    AuthService.endSession(cookies[SESSION_COOKIE]);
  }
  res.clearCookie(SESSION_COOKIE);
  res.json({ ok: true });
});

app.get('/api/auth/me', requireSession, (req, res) => {
  res.json({ userName: req.embySession!.userName });
});

// --- Catalog (proxied - the browser never talks to Emby directly) --------
// Thin wrappers over CatalogService - see its own file for the actual
// Emby calls/DTO shaping.

app.get('/api/catalog/search', requireSession, asyncRoute(async (req, res) => {
  const items = await CatalogService.search(req.embySession!, String(req.query.q || ''));
  res.json({ items });
}));

app.get('/api/catalog/item/:itemId', requireSession, asyncRoute(async (req, res) => {
  res.json(await CatalogService.getItem(req.embySession!, param(req, 'itemId')));
}));

// One entry per library, shown in the sidebar - see client/src's Shell.
app.get('/api/catalog/libraries', requireSession, asyncRoute(async (req, res) => {
  res.json({ libraries: await CatalogService.getLibraries(req.embySession!) });
}));

// Home page carousel: Emby's own "recently added" endpoint, one row per library.
app.get('/api/catalog/libraries/:libraryId/recent', requireSession, asyncRoute(async (req, res) => {
  res.json({ items: await CatalogService.getRecentItems(req.embySession!, param(req, 'libraryId')) });
}));

// Series -> Seasons -> Episodes, for the "Contenus vidéo en série" browsing page.
app.get('/api/catalog/series/:seriesId/seasons', requireSession, asyncRoute(async (req, res) => {
  res.json({ seasons: await CatalogService.getSeriesSeasons(req.embySession!, param(req, 'seriesId')) });
}));

app.get('/api/catalog/series/:seriesId/episodes', requireSession, asyncRoute(async (req, res) => {
  const seasonId = typeof req.query.seasonId === 'string' ? req.query.seasonId : undefined;
  res.json({ episodes: await CatalogService.getSeriesEpisodes(req.embySession!, param(req, 'seriesId'), seasonId) });
}));

// Library -> Artists -> Albums -> Tracks, for the "Musique" browsing pages.
app.get('/api/catalog/libraries/:libraryId/artists', requireSession, asyncRoute(async (req, res) => {
  res.json({ artists: await CatalogService.getArtists(req.embySession!, param(req, 'libraryId')) });
}));

app.get('/api/catalog/artists/:artistId/albums', requireSession, asyncRoute(async (req, res) => {
  res.json({ albums: await CatalogService.getArtistAlbums(req.embySession!, param(req, 'artistId')) });
}));

app.get('/api/catalog/albums/:albumId/tracks', requireSession, asyncRoute(async (req, res) => {
  res.json({ tracks: await CatalogService.getAlbumTracks(req.embySession!, param(req, 'albumId')) });
}));

// A playlist's own contents, in order - for views/playlist. See
// POST /api/parties below for actually launching one.
app.get('/api/catalog/playlists/:playlistId/items', requireSession, asyncRoute(async (req, res) => {
  res.json({ items: await CatalogService.getPlaylistItems(req.embySession!, param(req, 'playlistId')) });
}));

// Audio/subtitle tracks available for an item, read from Emby's own playback
// negotiation (PlaybackInfo) - powers the player's language/subtitle pickers.
app.get('/api/catalog/item/:itemId/playback-options', requireSession, asyncRoute(async (req, res) => {
  res.json(await CatalogService.getPlaybackOptions(req.embySession!, param(req, 'itemId')));
}));

app.get('/api/catalog/libraries/:libraryId/items', requireSession, asyncRoute(async (req, res) => {
  res.json({ items: await CatalogService.getLibraryItems(req.embySession!, param(req, 'libraryId')) });
}));

// Images/video/audio/subtitles are requested by <img>/<video>/<audio>/
// <track> elements, which send the session cookie (same-origin) but can't
// carry a bearer header - so these four routes check the cookie directly
// instead of using the requireSession middleware's JSON error response,
// which a browser media element ignores.

app.get('/api/catalog/image/:itemId', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  await CatalogService.proxyImage(req, res, session, param(req, 'itemId'));
}));

// The party's own shared Emby stream - one negotiated PlaybackInfo
// session reused by every member, instead of each viewer's own
// <video>/<audio> negotiating (and getting its own PlaySessionId)
// independently - see PartyStreamService and docs/architecture.md's
// "One shared Emby stream per party" section. Keyed by partyId, not
// itemId - the party object itself is the source of truth for what
// it's currently streaming and with which audio/quality choice, so
// there's nothing else a client could usefully put in this URL.
// requireSession's JSON error doesn't fit here either, same reasoning
// as the routes above (a <video>/<audio> element can't carry a bearer
// header).
app.get('/api/catalog/party-stream/:partyId/master.m3u8', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party || !party.members.has(session.userId)) {
    res.status(403).json({ error: "Tu n'es pas membre de cette watch party." });
    return;
  }
  await PartyStreamService.serveMasterPlaylist(req, res, party, session);
}));

// Everything an HLS playlist references (variant playlists, segments)
// comes back through here - see EmbyClient.rewritePlaylist.
app.get('/api/catalog/party-stream/:partyId/raw', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party || !party.members.has(session.userId)) {
    res.status(403).json({ error: "Tu n'es pas membre de cette watch party." });
    return;
  }
  await PartyStreamService.serveRawAsset(req, res, party, session);
}));

// A subtitle track's own text (WebVTT), for the player's native <track> -
// see CatalogService.proxySubtitle's own comment for why subtitles are
// rendered this way instead of asking Emby to burn them into the video.
app.get('/api/catalog/subtitle/:itemId/:subtitleIndex', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  await CatalogService.proxySubtitle(req, res, session, param(req, 'itemId'), param(req, 'subtitleIndex'));
}));

// The party's own self-hosted-ffmpeg burn-in stream (PGS/image subtitles
// only - see TranscodeService and Party.burnInSubtitleIndex's own
// comment); every other party keeps streaming through the party-stream
// routes above instead - PartyStreamService, not our own ffmpeg. Keyed
// by partyId, not itemId, same reasoning as those routes: the party
// object itself is the source of truth for which audio/subtitle
// combination is currently burned in, so there's nothing else a client
// could usefully put in this URL. requireSession's JSON error doesn't
// fit here either, same reasoning as the routes above.
app.get('/api/catalog/burn/:partyId/master.m3u8', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party || !party.members.has(session.userId)) {
    res.status(403).json({ error: "Tu n'es pas membre de cette watch party." });
    return;
  }
  if (!party.burnInSubtitleIndex) {
    res.status(409).json({ error: "Cette watch party n'a pas de flux incrusté actif." });
    return;
  }
  await TranscodeService.serveMasterPlaylist(req, res, party, session);
}));

app.get('/api/catalog/burn/:partyId/:segment', asyncRoute(async (req, res) => {
  const session = AuthService.sessionFromRequest(req);
  if (!session) { res.status(401).end(); return; }
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party || !party.members.has(session.userId)) {
    res.status(403).json({ error: "Tu n'es pas membre de cette watch party." });
    return;
  }
  await TranscodeService.serveSegment(req, res, party, param(req, 'segment'));
}));

// --- Parties ---------------------------------------------------------------
// No REST "list parties" endpoint: the home page's "watch parties en cours"
// list is live, over Socket.IO's "lobby" room (SocketGateway) - see
// docs/architecture.md. No join codes either - see PartyService's class
// comment for why a live list makes one redundant.

app.post('/api/parties', requireSession, asyncRoute(async (req, res) => {
  const itemId = req.body?.itemId;
  if (!itemId) {
    res.status(400).json({ error: 'itemId is required.' });
    return;
  }

  const session = req.embySession!;
  const item = await CatalogService.getRawItem(session, itemId);

  // A playlist itself was never something Emby could stream - launching
  // one means queuing everything inside it instead, a separate enough
  // shape (video queue vs. seeding the participative music queue several
  // tracks at once) that it's its own function rather than folded into
  // the single-item path below. See docs/architecture.md.
  if (item.Type === 'Playlist') {
    await createPartyFromPlaylist(res, session, itemId);
    return;
  }

  const mediaType: MediaType = item.Type === 'Audio' ? 'music' : 'video';

  // Starting a party from an episode queues the rest of the series from
  // there on, so the host can hit "next" (see SocketGateway) instead of
  // everyone having to separately start a new party per episode. Doesn't
  // apply to music - that party's queue is the live, participative one
  // instead (see MusicQueueService.init below).
  let queue: QueueItem[] | null = null;
  if (mediaType === 'video' && item.Type === 'Episode' && item.SeriesId) {
    const all = await CatalogService.getAllSeriesEpisodesRaw(session, item.SeriesId);
    const startIndex = all.findIndex((e) => e.Id === itemId);
    const remaining = startIndex >= 0 ? all.slice(startIndex) : [item];
    queue = remaining.map((e) => ({
      itemId: e.Id,
      itemName: formatEpisodeName(e),
      itemImageUrl: `/api/catalog/image/${e.Id}`
    }));
  }

  const party = PartyService.create(
    session.userId,
    session.userName,
    itemId,
    queue ? queue[0]!.itemName : item.Name,
    `/api/catalog/image/${itemId}`,
    queue,
    mediaType
  );
  PartyService.setMemberEmbyToken(party, session.userId, session.embyToken);

  if (mediaType === 'music') {
    MusicQueueService.init(party, {
      itemId,
      itemName: item.Name,
      artistName: item.AlbumArtist || item.Artists?.[0] || null,
      albumName: item.Album || null,
      itemImageUrl: `/api/catalog/image/${itemId}`,
      durationTicks: item.RunTimeTicks || null
    }, session.userId, session.userName);
  }

  SocketGateway.broadcastLobby(io); // the new party shows up on everyone's home page immediately
  res.json(PartyService.toPublicState(party, session.userId));
}));

function formatEpisodeName(episode: { ParentIndexNumber?: number; IndexNumber?: number; SeriesName?: string; Name: string }): string {
  if (episode.ParentIndexNumber != null && episode.IndexNumber != null) {
    const prefix = `S${episode.ParentIndexNumber}E${episode.IndexNumber}`;
    return episode.SeriesName ? `${episode.SeriesName} - ${prefix} - ${episode.Name}` : `${prefix} - ${episode.Name}`;
  }
  return episode.Name;
}

/**
 * The "launch this playlist" half of POST /api/parties above - kept
 * separate rather than merged into the single-item path, which is
 * already working/relied-upon and doesn't need touching for this.
 * splitPlaylistByMediaType (CatalogService) decides video vs music from
 * the playlist's first item and drops anything that doesn't match (a
 * mixed playlist - not something this app's party model can represent).
 */
async function createPartyFromPlaylist(res: Response, session: EmbySession, playlistId: string): Promise<void> {
  const raw = await CatalogService.getPlaylistItemsRaw(session, playlistId);
  const { mediaType, items } = splitPlaylistByMediaType(raw);
  if (!items.length) {
    res.status(400).json({ error: 'Cette playlist est vide.' });
    return;
  }
  if (items.length !== raw.length) {
    Logger.party(`playlist ${playlistId} is mixed-media - keeping only the ${items.length}/${raw.length} ${mediaType} item(s)`);
  }

  if (mediaType === 'music') {
    const first = items[0]!;
    const party = PartyService.create(
      session.userId, session.userName,
      first.Id, first.Name, `/api/catalog/image/${first.Id}`,
      null, mediaType
    );
    PartyService.setMemberEmbyToken(party, session.userId, session.embyToken);
    // Same mechanism POST /api/parties/:id/tracks already uses (see
    // below) - init seeds+auto-starts the first track, addTrack queues
    // the rest, exactly as if they'd been added one at a time.
    items.forEach((track, i) => {
      const trackInput = {
        itemId: track.Id,
        itemName: track.Name,
        artistName: track.AlbumArtist || track.Artists?.[0] || null,
        albumName: track.Album || null,
        itemImageUrl: `/api/catalog/image/${track.Id}`,
        durationTicks: track.RunTimeTicks || null
      };
      if (i === 0) {
        MusicQueueService.init(party, trackInput, session.userId, session.userName);
      } else {
        MusicQueueService.addTrack(party, trackInput, session.userId, session.userName);
      }
    });
    SocketGateway.broadcastLobby(io);
    res.json(PartyService.toPublicState(party, session.userId));
    return;
  }

  const queue: QueueItem[] = items.map((e) => ({
    itemId: e.Id,
    itemName: e.Type === 'Episode' ? formatEpisodeName(e) : e.Name,
    itemImageUrl: `/api/catalog/image/${e.Id}`
  }));
  const party = PartyService.create(
    session.userId, session.userName,
    queue[0]!.itemId, queue[0]!.itemName, queue[0]!.itemImageUrl,
    queue, mediaType
  );
  PartyService.setMemberEmbyToken(party, session.userId, session.embyToken);
  SocketGateway.broadcastLobby(io);
  res.json(PartyService.toPublicState(party, session.userId));
}

// Adding a track to a music party's shared queue is REST, not a socket
// event (see SocketGateway's top comment): the album-browsing page that
// this is actually called from has no live connection to the party it's
// adding into - only the player view does. MusicQueueService's own
// "queueUpdated" broadcast (wired to the real io instance via attachIo,
// below) reaches anyone actually connected regardless of which page made
// this request.
app.post('/api/parties/:partyId/tracks', requireSession, (req, res) => {
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party || party.mediaType !== 'music') {
    res.status(404).json({ error: 'Watch party musique introuvable.' });
    return;
  }
  const session = req.embySession!;
  if (!party.members.has(session.userId)) {
    res.status(403).json({ error: "Tu n'es pas membre de cette watch party." });
    return;
  }
  const track = req.body || {};
  if (!track.itemId) {
    res.status(400).json({ error: 'itemId is required.' });
    return;
  }
  MusicQueueService.addTrack(party, track, session.userId, session.userName);
  SocketGateway.broadcastLobby(io); // the queue/now-playing preview may have just changed
  res.json(PartyService.toPublicState(party, session.userId));
});

app.post('/api/parties/:partyId/join', requireSession, (req, res) => {
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party) {
    res.status(404).json({ error: 'Party introuvable (elle est peut-être terminée).' });
    return;
  }
  const session = req.embySession!;
  PartyService.join(party, session.userId, session.userName);
  PartyService.setMemberEmbyToken(party, session.userId, session.embyToken);
  SocketGateway.broadcastLobby(io); // member count changed - reflect it on the home page immediately
  res.json(PartyService.toPublicState(party, session.userId));
});

app.post('/api/parties/:partyId/leave', requireSession, (req, res) => {
  const party = PartyService.getById(param(req, 'partyId'));
  if (party) {
    // Shared with the socket "leave"/"disconnect" handlers so the host-
    // handoff notification and the lobby refresh only live in one place.
    SocketGateway.applyLeave(io, party, req.embySession!.userId);
  }
  res.json({ ok: true });
});

app.get('/api/parties/:partyId', requireSession, (req, res) => {
  const party = PartyService.getById(param(req, 'partyId'));
  if (!party) {
    res.status(404).json({ error: 'Party introuvable (elle est peut-être terminée).' });
    return;
  }
  res.json(PartyService.toPublicState(party, req.embySession!.userId));
});

// Catches whatever asyncRoute() forwarded (or a synchronous throw) -
// CatalogFetchError carries its own status/message; anything else is an
// unexpected bug, logged in full server-side but never leaked to the
// client beyond a generic message.
app.use((err: unknown, _req: Request, res: Response, _next: NextFunction) => {
  if (err instanceof CatalogFetchError) {
    res.status(err.status).json({ error: err.message });
    return;
  }
  console.error('[watchparty] unexpected error', err);
  res.status(500).json({ error: 'Erreur serveur.' });
});

const server = http.createServer(app);
// Same-origin by default (no `cors` option needed) - the client connects
// with a bare io() call, consistent with everything else in this app never
// crossing origins. Socket.IO's own heartbeat (pingInterval/pingTimeout,
// defaults are fine here) is what detects dead connections - see
// SocketGateway's top comment for why that matters.
const io = new SocketIoServer<ClientToServerEvents, ServerToClientEvents>(server);
SocketGateway.attach(io, (h) => AuthService.parseCookies(h), (id) => AuthService.getSession(id));

// Gives MusicQueueService a way to broadcast from its own internal
// auto-advance timer (no socket/request in scope there at all) and to
// refresh the home page's lobby card when the timer - not a person
// clicking anything - changes what's playing. Passed in rather than
// imported directly from SocketGateway/MusicQueueService to avoid a
// circular import between the two.
MusicQueueService.attachIo(io, () => SocketGateway.broadcastLobby(io));

setInterval(() => PartyService.removeIdleParties(4 * 60 * 60 * 1000), 10 * 60 * 1000);
// Shorter idle window than parties themselves: a burn-in session holds a
// real ffmpeg process + disk, not just an in-memory object, so a paused/
// abandoned one is worth reclaiming sooner. Mostly a backstop - the
// normal path is PartyService.leave's destroy branch ending it immediately.
setInterval(() => TranscodeService.reapIdleSessions(30 * 60 * 1000), 5 * 60 * 1000);
// Same reasoning as TranscodeService's own reaper just above - a cached
// negotiation is mostly harmless to keep around, but there's no reason
// to hold one for a party nobody's actively streaming from any more.
// Mostly a backstop too - the normal path is PartyService.leave's
// destroy branch (and an item/track change) ending it immediately.
setInterval(() => PartyStreamService.reapIdleSessions(30 * 60 * 1000), 5 * 60 * 1000);

// Pushes every connected member's own progress to Emby, under their own
// account - see docs/architecture.md's "Sync watch-party progress back
// to Emby" section for the full design and its deliberate v1 scope
// (periodic Progress reports only, no explicit start/stop). Best-effort:
// PlaystateService.reportProgress swallows its own failures, so one bad
// token or a transient Emby hiccup never stops the rest of this sweep.
// MediaSourceId/PlaySessionId come from PartyStreamService's own cache,
// read-only (getCachedPlaybackIds never negotiates) - both matter to the
// real Progress endpoint in practice (see PlaystateService.ts), and
// skipping a party entirely when nothing's cached yet (no one has hit
// play this session) is simpler and cheaper than this sweep ever
// negotiating a stream of its own just to get them.
setInterval(() => {
  for (const party of PartyService.listActive()) {
    const state = PartyService.getCurrentPlaybackState(party);
    if (!state) continue; // nothing currently playing (e.g. an empty music queue)
    const playbackIds = PartyStreamService.getCachedPlaybackIds(party.id);
    if (!playbackIds) continue; // nothing negotiated yet this session - Progress needs it
    for (const member of party.members.values()) {
      if (!member.connection || !member.embyToken) continue;
      PlaystateService.reportProgress(member.embyToken, member.userId, state.itemId, playbackIds.mediaSourceId, playbackIds.playSessionId, state.positionTicks, state.isPaused);
    }
  }
}, 20 * 1000);

server.listen(PORT, () => {
  console.log(`[watchparty] listening on :${PORT} (Emby server: ${EMBY_SERVER_URL || 'NOT SET'})`);
});