/* ============================================================================
 * server.js — YT Player PWA backend
 *
 * Runtime:  Bun (https://bun.sh)
 * Framework: Hono v4
 * DB:        libsql (concurrent SQLite fork, embedded file mode)
 *
 * Endpoints:
 *   GET  /api/search?q=<query>         yt-dlp search → slim card array
 *   GET  /api/channel?c=<channel>      yt-dlp channel uploads → slim card array
 *   GET  /api/streams?v=<videoId>      yt-dlp stream info → {meta, audioUrl, qualities} (proxied URLs)
 *   GET  /api/play?v=<id>&f=<fmt>      same-origin playback proxy (Range-aware) → media bytes
 *   GET  /api/download/:videoId        proxy best progressive stream → binary
 *   GET  /api/version                  { version }
 *   POST /api/user/sync                upsert user playlists + last-seen version
 *   GET  /api/user/data?fp=<fp>        retrieve stored playlists + history
 *   POST /api/playlist/share           share a single playlist → { ok, code }
 *   GET  /api/playlist/shared?code=<code> retrieve shared playlist → { ok, code, playlist, createdAt }
 *   GET  /api/playlist/expand?url=<url> expand YouTube playlist → { ok, title, entries, truncated? }
 *   GET  /*                            serve frontend/public static files
 *
 * JSON shapes mirror the Tauri (Rust) bridge exactly so the existing app.js
 * UI code works without modification in WEB mode.
 * ========================================================================== */

import { Hono }         from 'hono';
import { serveStatic }  from 'hono/bun';
import { logger }       from 'hono/logger';
import { spawn }        from 'node:child_process';
import { createServer } from 'node:http';
import { readFileSync, readdirSync, existsSync, statSync, openSync, unlinkSync, createReadStream } from 'node:fs';
import { Readable }      from 'node:stream';
import { tmpdir }        from 'node:os';
import { createHash }    from 'node:crypto';
import { initDb, upsertUser, recordVideoAccess, getUserData, createProfile, getProfile, saveProfile, createSharedPlaylist, getSharedPlaylist } from './db.js';

// A media proxy must not die because one client's stream hit an edge case
// (see /api/play cancel()): log and keep serving instead of crash-looping.
process.on('uncaughtException', (err) => console.error('[ytplayer] uncaught exception:', err));
process.on('unhandledRejection', (err) => console.error('[ytplayer] unhandled rejection:', err));

const PORT        = parseInt(process.env.PORT || '3000', 10);
const APP_VERSION = process.env.APP_VERSION || '1.0.0';
const YTDLP       = process.env.YTDLP_PATH  || 'yt-dlp';
const FFMPEG      = process.env.FFMPEG_PATH || 'ffmpeg';
// Cap for server-side SAVE downloads. yt-dlp with -N 4 pinned the homelab's
// whole downlink (~7.6 MB/s measured), and since /api/play fetches its own
// googlevideo slices over the same link, one long save starved every
// concurrent playback (stalled at ~27 s, 11 KB/s). Leave headroom.
const DOWNLOAD_RATE = process.env.DOWNLOAD_RATE || '2M';

// Saves run ONE AT A TIME. Two concurrent rate-capped saves plus playback
// still filled the homelab's ~7.5 MB/s downlink and playback starved, so
// additional saves wait their turn (the client just sees a longer save).
let saveChain = Promise.resolve();
function withSaveSlot(fn) {
  const run = saveChain.then(fn, fn);
  saveChain = run.catch(() => {});
  return run;
}

// ----------------------------------------------------------------------------
// BUILD_TAG — must be DETERMINISTIC across restarts of identical code.
//
// Previously this was `Date.now().toString(36)`, which changes every time the
// process starts even if nothing was deployed (crash-loop, healthcheck
// restart, container reschedule). The frontend's checkBuildTag() polls
// /api/version and re-shows the "Update available" modal the instant the tag
// drifts — so a restarting-but-unchanged server kept re-announcing an update
// that never actually happened, and clicking "Refresh UI" (which itself
// reloads the page and re-polls) never made the prompt go away for good.
//
// Fix: hash the actual served frontend files. Identical code → identical
// hash → identical tag, no matter how many times the process restarts. A
// real deploy (changed files) still produces a new tag as intended.
// process.env.BUILD_TAG still wins if a CI pipeline already injects a git
// SHA — that's an even better source of truth than a content hash.
// ----------------------------------------------------------------------------
function computeBuildTag() {
  try {
    // Hash EVERY served frontend file (recursively, in sorted order), not a
    // hand-picked subset — a change to any shell file (e.g. sw-update.js or
    // opfs.js) must produce a new tag, or clients keep their old SW cache
    // and never receive the change.
    const hash = createHash('sha256');
    const walk = (dir) => {
      for (const name of readdirSync(dir).sort()) {
        const path = `${dir}/${name}`;
        if (statSync(path).isDirectory()) walk(path);
        else { hash.update(path); hash.update(readFileSync(path)); }
      }
    };
    walk('./public');
    return hash.digest('hex').slice(0, 12);
  } catch {
    // Frontend files not readable (e.g. unit tests run outside ./public) —
    // fall back to a fixed tag rather than Date.now(), so it still never
    // drifts spuriously between restarts.
    return 'dev-build';
  }
}

const BUILD_TAG = process.env.BUILD_TAG || computeBuildTag();

// BUILD_TIME — human-readable "when was this image built". Written by the
// Dockerfile at image build time (never at container start, so restarts
// don't drift it). Kept OUTSIDE ./public so it can't perturb BUILD_TAG.
const BUILD_TIME = process.env.BUILD_TIME || (() => {
  try { return readFileSync('./build-time.txt', 'utf8').trim(); }
  catch { return null; }
})();

const SEARCH_LIMIT  = 25;
const CHANNEL_LIMIT = 60;

// ============================================================================
// yt-dlp helpers
// ============================================================================

// Run yt-dlp asynchronously and resolve stdout as a string.
// MUST stay async (spawn, not spawnSync): a sync child process blocks Bun's
// event loop for the full yt-dlp runtime (~2-3s per call), which stalls every
// concurrent request — including in-flight /api/download proxy streams, which
// Bun then kills at its idle timeout ("fetch failed" mid-download on clients).
// Rejects on non-zero exit.
function runYtdlp(args, { signal } = {}) {
  return new Promise((resolve, reject) => {
    const child = spawn(YTDLP, args, { stdio: ['ignore', 'pipe', 'pipe'] });
    // Kill the download when the requesting client goes away — otherwise an
    // aborted/retried save leaves yt-dlp running to completion (8 copies of
    // one video were found pulling in parallel after the client retried).
    if (signal) {
      if (signal.aborted) child.kill('SIGTERM');
      else signal.addEventListener('abort', () => child.kill('SIGTERM'), { once: true });
    }
    let out = '';
    let err = '';
    child.stdout.setEncoding('utf8');
    child.stderr.setEncoding('utf8');
    child.stdout.on('data', (d) => { out += d; });
    child.stderr.on('data', (d) => { err += d; });
    child.on('error', (e) => reject(new Error('yt-dlp not found: ' + e.message)));
    child.on('close', (code) => {
      if (code !== 0) reject(new Error(err.trim() || 'yt-dlp exited with code ' + code));
      else resolve(out);
    });
  });
}

// YouTube intermittently answers the default (web) innertube client with
// "Sign in to confirm you're not a bot" — a per-IP rate signal, not a
// per-video one, so the SAME video that just saved fine fails minutes later
// and the user sees "sign in required". Other player clients are not gated by
// that check from a datacentre IP, so retry the whole yt-dlp call against each
// in turn instead of demanding cookies. Order is quality-first: web_embedded
// still exposes the adaptive DASH ladder (399+251), while tv_simply /
// android_vr / mweb typically only offer progressive itag 18 (360p) — a 360p
// save beats a failed save.
const BOT_CHECK_RE = /Sign in to confirm|not a bot|confirm you.{0,3}re not a bot/i;
const FALLBACK_CLIENTS = (process.env.YTDLP_FALLBACK_CLIENTS
  || 'web_embedded,tv_simply,android_vr,mweb').split(',').map((s) => s.trim()).filter(Boolean);
// Optional cookies jar (Netscape format) for the rare case every client is
// gated. Mounted read-only; absent by default and never required.
const YTDLP_COOKIES = process.env.YTDLP_COOKIES || '';

function withCookies(args) {
  if (!YTDLP_COOKIES || !existsSync(YTDLP_COOKIES)) return args;
  return ['--cookies', YTDLP_COOKIES, ...args];
}

// runYtdlp + bot-check fallback. Every YouTube-facing call goes through this.
async function runYtdlpResilient(args, opts = {}) {
  const hasClientArg = args.some((a) => String(a).includes('player_client='));
  try {
    return await runYtdlp(withCookies(args), opts);
  } catch (err) {
    if (hasClientArg || !BOT_CHECK_RE.test(err.message)) throw err;
    if (opts.signal?.aborted) throw err;
    let last = err;
    for (const client of FALLBACK_CLIENTS) {
      if (opts.signal?.aborted) throw last;
      try {
        const out = await runYtdlp(
          withCookies(['--extractor-args', `youtube:player_client=${client}`, ...args]),
          opts,
        );
        console.warn(`[ytplayer] bot check on default client, succeeded via player_client=${client}`);
        return out;
      } catch (e) {
        last = e;
        // A client that simply lacks the requested format is not a bot check;
        // keep walking the list either way, but surface the last real error.
        if (!BOT_CHECK_RE.test(e.message) && !/format is not available/i.test(e.message)) throw e;
      }
    }
    throw last;
  }
}

// Run ffmpeg the same way — async spawn so a multi-minute trim/concat never
// blocks Bun's event loop. Rejects on non-zero exit with ffmpeg's stderr tail.
function runFfmpeg(args) {
  return new Promise((resolve, reject) => {
    const child = spawn(FFMPEG, args, { stdio: ['ignore', 'ignore', 'pipe'] });
    let err = '';
    child.stderr.setEncoding('utf8');
    // ffmpeg is extremely chatty on stderr; keep only the tail so an error
    // message stays useful without buffering the whole progress log.
    child.stderr.on('data', (d) => { err = (err + d).slice(-4000); });
    child.on('error', (e) => reject(new Error('ffmpeg not found: ' + e.message)));
    child.on('close', (code) => {
      if (code !== 0) reject(new Error(err.trim() || 'ffmpeg exited with code ' + code));
      else resolve();
    });
  });
}

// Parse the compact "s-e,s-e" keep-segment string (see frontend/video-edit.js)
// into an array of {start,end} second ranges. Skips malformed / non-increasing
// tokens; returns [] on empty or all-garbage input. Kept in lockstep with the
// frontend parseKeepParam so both ends agree on the wire format.
function parseKeepParam(str) {
  if (typeof str !== 'string') return [];
  const out = [];
  for (const tok of str.split(',')) {
    const t = tok.trim();
    if (!t) continue;
    const m = t.match(/^(\d+(?:\.\d+)?)-(\d+(?:\.\d+)?)$/);
    if (!m) continue;
    const a = parseFloat(m[1]);
    const b = parseFloat(m[2]);
    if (!isFinite(a) || !isFinite(b) || b <= a) continue;
    out.push({ start: a, end: b });
  }
  return out;
}

// Build an ffmpeg filter_complex that trims `src` to the keep segments and
// concatenates them back into a single continuous stream. Re-encodes (the cut
// points rarely fall on keyframes, so stream-copy would glitch), producing one
// clean mp4. Returns the ffmpeg argv (input already appended by the caller).
function buildTrimArgs(keep) {
  const parts = [];
  keep.forEach((k, i) => {
    parts.push(
      `[0:v]trim=start=${k.start}:end=${k.end},setpts=PTS-STARTPTS[v${i}]`,
      `[0:a]atrim=start=${k.start}:end=${k.end},asetpts=PTS-STARTPTS[a${i}]`,
    );
  });
  const concatInputs = keep.map((_, i) => `[v${i}][a${i}]`).join('');
  const filter = parts.join(';') + ';' +
    `${concatInputs}concat=n=${keep.length}:v=1:a=1[outv][outa]`;
  return [
    '-filter_complex', filter,
    '-map', '[outv]', '-map', '[outa]',
    '-c:v', 'libx264', '-preset', 'veryfast', '-crf', '20',
    '-c:a', 'aac', '-b:a', '160k',
    '-movflags', '+faststart',
  ];
}

// Helpers to pick the right field from a yt-dlp JSON record
function pick(obj, ...keys) {
  for (const k of keys) {
    const v = obj[k];
    if (v && typeof v === 'string' && v.trim()) return v.trim();
  }
  return '';
}

function pickChannel(obj)    { return pick(obj, 'channel', 'uploader'); }
function pickChannelUrl(obj) { return pick(obj, 'channel_url', 'uploader_url'); }
function pickChannelId(obj)  { return pick(obj, 'channel_id', 'uploader_id'); }

// Normalise a flat-playlist yt-dlp record into the slim UI card shape
function slimEntry(j) {
  const id = pick(j, 'id');
  if (!id) return null;
  return {
    id,
    title:      pick(j, 'title') || '(untitled)',
    channel:    pickChannel(j),
    channelId:  pickChannelId(j),
    channelUrl: pickChannelUrl(j),
    duration:   typeof j.duration === 'number' ? j.duration : 0,
    thumbnail:  `https://i.ytimg.com/vi/${id}/mqdefault.jpg`,
  };
}

// Parse multi-line JSON output from yt-dlp --dump-json --flat-playlist
function parseCards(output) {
  const results = [];
  for (const line of output.split('\n')) {
    const t = line.trim();
    if (!t) continue;
    try {
      const j = JSON.parse(t);
      const card = slimEntry(j);
      if (card) results.push(card);
    } catch { /* skip malformed lines */ }
  }
  return results;
}

// Resolve a channel identifier to a /videos URL yt-dlp can fetch
function channelToUrl(c) {
  let base = c.trim();
  if (!base.startsWith('http')) {
    base = base.startsWith('@') ? `https://www.youtube.com/${base}`
         : base.startsWith('UC') ? `https://www.youtube.com/channel/${base}`
         : `https://www.youtube.com/@${base}`;
  }
  base = base.replace(/\/$/, '');
  return base.endsWith('/videos') ? base : base + '/videos';
}

// ============================================================================
// App setup
// ============================================================================

const app = new Hono();
app.use('*', logger());

// ============================================================================
// API routes
// ============================================================================

// GET /api/version
// Returns version string + a build tag that changes on every server restart/deploy.
// Clients poll this to detect when a new build is live and prompt a reload.
app.get('/api/version', (c) =>
  c.json(
    { version: APP_VERSION, buildTag: BUILD_TAG, buildTime: BUILD_TIME },
    200,
    { 'Cache-Control': 'no-store, no-cache, must-revalidate' }
  )
);

// GET /api/search?q=<query>
app.get('/api/search', async (c) => {
  const q = (c.req.query('q') || '').trim();
  if (!q) return c.json({ ok: false, error: 'empty query' }, 400);

  try {
    const out = await runYtdlpResilient([
      `ytsearch${SEARCH_LIMIT}:${q}`,
      '--dump-json', '--flat-playlist',
      '--no-warnings', '--ignore-errors',
    ]);
    return c.json({ ok: true, results: parseCards(out) });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// GET /api/channel?c=<channel>
app.get('/api/channel', async (c) => {
  const chan = (c.req.query('c') || '').trim();
  if (!chan) return c.json({ ok: false, error: 'missing channel' }, 400);

  try {
    const url = channelToUrl(chan);
    const out = await runYtdlpResilient([
      url,
      '--dump-json', '--flat-playlist',
      '--no-warnings', '--ignore-errors',
      '--playlist-end', String(CHANNEL_LIMIT),
    ]);
    const results = parseCards(out);
    // Extract channel name + URL from the first record
    const first = results[0];
    let channelName = '', channelUrl = '';
    for (const line of out.split('\n')) {
      const t = line.trim();
      if (!t) continue;
      try {
        const j = JSON.parse(t);
        channelName = channelName || pickChannel(j);
        channelUrl  = channelUrl  || pickChannelUrl(j);
        if (channelName && channelUrl) break;
      } catch { /* skip */ }
    }
    return c.json({ ok: true, channel: channelName || (first?.channel || ''), channelUrl, results });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// ============================================================================
// Stream resolution + same-origin playback proxy
// ----------------------------------------------------------------------------
// googlevideo stream URLs are bound to the innertube client AND the IP that
// extracted them, and they expire (~6h via their `expire=` param). Handing
// them straight to the browser — which fetches from a DIFFERENT IP than this
// server — is what produced the intermittent 403s on playback (only the
// download path was ever fixed, in 70b5214). So playback now flows through
// /api/play: the browser hits our own origin, and THIS server fetches the
// googlevideo bytes (its IP matches the extractor) using yt-dlp's own
// http_headers, forwarding the browser's Range header so seeking still works.
// ============================================================================

// videoId -> { info, formats:[{formatId,height,vcodec,acodec,abr,ext,url,headers}], expiresAt }
const streamCache = new Map();
const STREAM_CACHE_MAX = 200;
// Max bytes per upstream googlevideo request (its adaptive streams are cut
// after ~10 MB; matches yt-dlp's http_chunk_size).
const PLAY_CHUNK = 10 * 1024 * 1024 - 1024;

// googlevideo URLs carry `expire=<unix-seconds>`; return that as an ms epoch.
function parseExpiry(url) {
  const m = /[?&]expire=(\d+)/.exec(url || '');
  return m ? Number(m[1]) * 1000 : 0;
}

// Resolve (and briefly cache) a video's playable formats via yt-dlp -J. The
// cache spares a fresh ~2-3s yt-dlp run on every Range request the media
// element fires; its TTL is bounded a minute inside the URLs' own expiry.
async function resolveStreams(videoId) {
  const now = Date.now();
  const cached = streamCache.get(videoId);
  if (cached && now < cached.expiresAt) return cached;

  const out = await runYtdlpResilient(['-J', '--no-warnings', `https://www.youtube.com/watch?v=${videoId}`]);
  const info = JSON.parse(out);
  const raw = Array.isArray(info.formats) ? info.formats : [];
  const formats = [];
  let soonest = Infinity;
  for (const f of raw) {
    if (!f.url) continue;
    // Only keep direct https byte streams. Newer yt-dlp also surfaces HLS
    // (m3u8/m3u8_native) and DASH-segment formats whose `url` is a manifest,
    // not media bytes — proxying those hands the <video> element an m3u8 it
    // can't play (Chrome) and defeats Range seeking (416). https formats are
    // exactly the ones the dual-stream engine relied on before this change.
    if (f.protocol && f.protocol !== 'https') continue;
    const exp = parseExpiry(f.url);
    if (exp) soonest = Math.min(soonest, exp);
    formats.push({
      formatId: String(f.format_id || ''),
      height:   f.height || 0,
      vcodec:   f.vcodec,
      acodec:   f.acodec,
      abr:      f.abr || 0,
      ext:      f.ext || '',
      url:      f.url,
      headers:  f.http_headers || {},
    });
  }
  const ttlUntil = soonest === Infinity ? now + 30 * 60_000 : soonest - 60_000;
  const expiresAt = Math.max(now + 60_000, Math.min(ttlUntil, now + 3 * 3600_000));
  const entry = { info, formats, expiresAt };
  if (streamCache.size >= STREAM_CACHE_MAX) streamCache.delete(streamCache.keys().next().value);
  streamCache.set(videoId, entry);
  return entry;
}

const isVideoFmt = (f) => f.vcodec && f.vcodec !== 'none';
const isAudioFmt = (f) => f.acodec && f.acodec !== 'none';

// Highest-bitrate audio-only format (prefer mp4a/m4a).
function pickBestAudio(formats) {
  let best = null, bestScore = -1;
  for (const f of formats) {
    if (isVideoFmt(f) || !isAudioFmt(f)) continue;
    let score = f.abr || 0;
    if (f.acodec && f.acodec.includes('mp4a')) score += 1000;
    if (score > bestScore) { bestScore = score; best = f; }
  }
  return best;
}

// Pick the format /api/play should serve — by exact id first, then by the same
// height/progressive-first ordering /api/streams used to build the quality.
function pickFormat(formats, { formatId, wantAudio, wantHeight }) {
  if (formatId) {
    const byId = formats.find((f) => f.formatId === formatId);
    if (byId) return byId;
  }
  if (wantAudio) return pickBestAudio(formats);
  if (wantHeight) {
    for (const wantProg of [false, true]) {
      for (const f of formats) {
        if (!isVideoFmt(f)) continue;
        if (isAudioFmt(f) !== wantProg) continue;
        if ((f.height || 0) === wantHeight) return f;
      }
    }
  }
  return null;
}

// GET /api/streams?v=<videoId> — meta + proxied audio/quality URLs.
app.get('/api/streams', async (c) => {
  const videoId = (c.req.query('v') || '').replace(/[/\\:?<>|*"]/g, '').trim();
  if (!videoId) return c.json({ ok: false, error: 'missing videoId' }, 400);

  try {
    const { info, formats } = await resolveStreams(videoId);

    // Proxied audio URL (same-origin, re-resolved fresh on each play).
    const bestAudio = pickBestAudio(formats);
    const audioUrl = bestAudio
      ? `/api/play?v=${videoId}&audio=1&f=${encodeURIComponent(bestAudio.formatId)}`
      : null;

    // Quality list — one entry per height. ADAPTIVE (video-only, paired with
    // the separate audioUrl for dual-stream playback) is preferred over
    // progressive single-file: adaptive https streams proxy reliably, while
    // progressive muxed formats (itag 18 and friends) are increasingly
    // SABR-gated and flaky. Progressive is kept only when no adaptive stream
    // exists at that height.
    const qualities = [];
    const seen = new Set();
    for (const wantProg of [false, true]) {
      for (const f of formats) {
        if (!isVideoFmt(f)) continue;
        if (isAudioFmt(f) !== wantProg) continue;
        const h = f.height || 0;
        if (h <= 0 || seen.has(h)) continue;
        seen.add(h);
        qualities.push({
          label:    h + 'p',
          height:   h,
          hasAudio: wantProg,
          url:      `/api/play?v=${videoId}&h=${h}&f=${encodeURIComponent(f.formatId)}`,
          ext:      f.ext || '',
        });
      }
    }
    qualities.sort((a, b) => b.height - a.height);

    // Nothing proxyable (live streams only expose HLS manifests) — say so
    // instead of handing the player an empty list it silently stalls on.
    if (!qualities.length && !audioUrl) {
      const live = info.is_live || info.live_status === 'is_live';
      return c.json({ ok: false, error: live ? 'Live streams are not supported' : 'No playable formats for this video' }, 422);
    }

    return c.json({
      ok: true,
      data: {
        meta: {
          id:         videoId,
          title:      pick(info, 'title') || '(untitled)',
          channel:    pickChannel(info),
          channelId:  pickChannelId(info),
          channelUrl: pickChannelUrl(info),
          duration:   typeof info.duration === 'number' ? info.duration : 0,
          thumbnail:  `https://i.ytimg.com/vi/${videoId}/hqdefault.jpg`,
        },
        audioUrl,
        qualities,
      },
    });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// Stream a single format straight out of yt-dlp's stdout. Some formats
// (notably progressive itag 18, and any SABR-gated stream) 403 on a plain GET
// even from the extractor IP — the bytes are only reachable through yt-dlp's
// full protocol. This can't honour a byte Range (yt-dlp writes start-to-end to
// the pipe), so it always answers 200; the media element still plays, it just
// can't seek past what it has buffered. Used only as the /api/play fallback.
//
// It PEEKS the first chunk before committing to a 200: if yt-dlp errors or
// exits without emitting any bytes (stale binary, ffmpeg segfault on merge,
// dead itag), it resolves to null so the caller can return a real error and
// the frontend advances to the next candidate instead of playing an empty 200.
function ytdlpPipeResponse(videoId, formatArgs, contentType) {
  return new Promise((resolve) => {
    const child = spawn(YTDLP, [
      `https://www.youtube.com/watch?v=${videoId}`,
      '--no-warnings', '--no-playlist',
      ...formatArgs,
      '-o', '-',
    ], { stdio: ['ignore', 'pipe', 'ignore'] });

    let settled = false;
    const finish = (val) => { if (!settled) { settled = true; resolve(val); } };

    child.stdout.once('data', (first) => {
      // Re-emit the peeked chunk so the response stream is byte-complete.
      child.stdout.unshift(first);
      finish(new Response(Readable.toWeb(child.stdout), {
        status: 200,
        headers: {
          'Content-Type':  contentType,
          'Accept-Ranges': 'none',
          'Cache-Control': 'no-store',
        },
      }));
    });
    child.on('error', () => { try { child.kill(); } catch {} finish(null); });
    child.on('close', () => finish(null)); // closed before any data → failure
  });
}

// GET /api/play?v=<id>&f=<formatId>[&h=<height>][&audio=1]
// Same-origin streaming proxy for playback. Fetches the googlevideo bytes from
// THIS server (whose IP matches the extractor) with yt-dlp's own http_headers,
// forwarding the browser's Range header so seeking works. This is what makes
// the previously-403ing direct URLs play reliably. If the direct URL still
// 403s (SABR/itag-18 formats reachable only via yt-dlp's protocol), it falls
// back to piping yt-dlp itself.
app.get('/api/play', async (c) => {
  const videoId = (c.req.query('v') || '').replace(/[/\\:?<>|*"]/g, '').trim();
  if (!videoId) return c.json({ ok: false, error: 'missing videoId' }, 400);
  const sel = {
    formatId:   (c.req.query('f') || '').trim(),
    wantAudio:  c.req.query('audio') === '1',
    wantHeight: Number(c.req.query('h') || 0),
  };
  const range = c.req.header('range');

  // Fetch the chosen format's bytes; on a stale-URL 403/410 drop the cache and
  // re-resolve once before giving up.
  async function upstreamFetch(forceFresh) {
    if (forceFresh) streamCache.delete(videoId);
    const { formats } = await resolveStreams(videoId);
    const fmt = pickFormat(formats, sel);
    if (!fmt) return { error: 'no matching format' };
    const headers = { ...fmt.headers };
    // Always ask upstream for a bounded slice (see PLAY_CHUNK below); the
    // splicer extends it to the client's full requested range.
    const rq = /bytes=(\d+)-(\d*)/.exec(range || '');
    const from = rq ? Number(rq[1]) : 0;
    const to = rq && rq[2] !== '' ? Math.min(Number(rq[2]), from + PLAY_CHUNK - 1) : from + PLAY_CHUNK - 1;
    headers['Range'] = range && !rq ? range : `bytes=${from}-${to}`;
    return { fmt, res: await fetch(fmt.url, { headers, redirect: 'follow' }) };
  }

  try {
    let attempt = await upstreamFetch(false);
    if (attempt.error) return c.json({ ok: false, error: attempt.error }, 404);
    if (attempt.res.status === 403 || attempt.res.status === 410) {
      const retry = await upstreamFetch(true);
      if (!retry.error && retry.res) attempt = retry;
    }

    // Direct URL is genuinely ungettable (SABR / itag-18) — let yt-dlp fetch it.
    if (attempt.res.status === 403 || attempt.res.status === 410) {
      const fmtArgs = sel.formatId ? ['-f', sel.formatId]
        : sel.wantAudio ? ['-f', 'bestaudio[ext=m4a]/bestaudio']
        : sel.wantHeight ? ['-f', `best[height=${sel.wantHeight}]/bv*[height=${sel.wantHeight}]`]
        : ['-f', 'best'];
      const piped = await ytdlpPipeResponse(videoId, fmtArgs, sel.wantAudio ? 'audio/mp4' : 'video/mp4');
      if (piped) return piped;
      return c.json({ ok: false, error: 'stream unavailable (403)' }, 502);
    }

    const up = attempt.res;
    const headers = new Headers();
    headers.set('Content-Type', up.headers.get('content-type') || (sel.wantAudio ? 'audio/mp4' : 'video/mp4'));
    headers.set('Accept-Ranges', 'bytes');
    headers.set('Cache-Control', 'no-store');

    // googlevideo silently closes adaptive-stream connections after ~10 MB
    // (yt-dlp's own `http_chunk_size` exists for exactly this), so a single
    // forwarded `bytes=0-` truncated at ~30 s of 720p and the <video> element
    // stalled with no error. Re-issue upstream fetches in ≤10 MB Range slices
    // and splice them into ONE response body that is byte-complete for the
    // client's requested range.
    const cr = /bytes (\d+)-(\d+)\/(\d+|\*)/.exec(up.headers.get('content-range') || '');
    const total = cr && cr[3] !== '*' ? Number(cr[3])
      : up.status === 200 ? Number(up.headers.get('content-length') || 0) : 0;
    if (!total || up.status !== 206 && up.status !== 200) {
      for (const k of ['content-length', 'content-range']) {
        const v = up.headers.get(k);
        if (v) headers.set(k, v);
      }
      return new Response(up.body, { status: up.status, headers });
    }

    const rq = /bytes=(\d*)-(\d*)/.exec(range || '');
    let start = cr ? Number(cr[1]) : 0;
    let end = total - 1;
    if (rq && rq[2] !== '') end = Math.min(total - 1, Number(rq[2]));
    if (rq && rq[1] === '' && rq[2] !== '') { start = Math.max(0, total - Number(rq[2])); end = total - 1; }
    const length = end - start + 1;

    const fmt = attempt.fmt;
    // Client-disconnect handling: the active upstream body is LOCKED by its
    // reader, so `body.cancel()` on it throws ("Cannot cancel a locked
    // ReadableStream") — and an exception thrown from cancel() took the whole
    // Bun process down on every seek / quality switch / aborted fetch. Cancel
    // through the reader instead, and stop the slice loop via a flag.
    let aborted = false;
    let reader = null;
    const body = new ReadableStream({
      async start(ctrl) {
        // Upstream body is a slice already; the slice boundaries below are
        // relative to `start`, and the first slice reuses the in-flight fetch.
        let pos = start;
        let res = up;
        try {
          while (pos <= end && !aborted) {
            const sliceEnd = Math.min(end, pos + PLAY_CHUNK - 1);
            if (res === null) {
              res = await fetch(fmt.url, { headers: { ...fmt.headers, Range: `bytes=${pos}-${sliceEnd}` }, redirect: 'follow' });
              if (res.status !== 206 && res.status !== 200) throw new Error('upstream ' + res.status);
            }
            reader = res.body.getReader();
            let got = 0;
            while (got < sliceEnd - pos + 1 && !aborted) {
              const { value, done } = await reader.read();
              if (done) break;
              const room = sliceEnd - pos + 1 - got;
              const chunk = value.length > room ? value.subarray(0, room) : value;
              ctrl.enqueue(chunk);
              got += chunk.length;
            }
            try { await reader.cancel(); } catch {}
            reader = null;
            if (aborted) break;
            if (got === 0) throw new Error('upstream returned no bytes');
            pos += got;
            res = null;
          }
          if (!aborted) ctrl.close();
        } catch (err) {
          if (!aborted) { try { ctrl.error(err); } catch {} }
        }
      },
      cancel() {
        aborted = true;
        const r = reader;
        if (r) r.cancel().catch(() => {});
      },
    });

    headers.set('Content-Length', String(length));
    if (range) {
      headers.set('Content-Range', `bytes ${start}-${end}/${total}`);
      return new Response(body, { status: 206, headers });
    }
    return new Response(body, { status: 200, headers });
  } catch (err) {
    return c.json({ ok: false, error: 'stream proxy failed: ' + err.message }, 502);
  }
});

// Download via yt-dlp into a self-cleaning temp file, then stream it.
// yt-dlp MUST perform the HTTP fetch itself: googlevideo stream URLs are
// bound to the innertube client that extracted them, so resolving the URL
// with --get-url and re-fetching it server-side with hand-rolled browser
// headers intermittently got 403s from the YouTube CDN when the User-Agent
// didn't match the extraction client.
// Live streams have no end: yt-dlp/ffmpeg would pull the HLS manifest forever
// (one such "save" ran for an hour and ate 14 GB). Refuse them up front.
const MAX_SAVE_SECONDS = Number(process.env.MAX_SAVE_SECONDS || 3 * 3600);
async function assertNotLive(videoId) {
  const { info } = await resolveStreams(videoId);
  if (info.is_live || info.live_status === 'is_live' || info.live_status === 'post_live') {
    throw new Error('live streams cannot be saved');
  }
  if (typeof info.duration === 'number' && info.duration > MAX_SAVE_SECONDS) {
    throw new Error(`video is too long to save (${Math.round(info.duration / 3600)} h, limit ${MAX_SAVE_SECONDS / 3600} h)`);
  }
}

// Same video + same format args requested while a download is already in
// flight (the OPFS worker retries, then the main-thread fallback retries
// again) share ONE yt-dlp run instead of spawning another each time.
const inflightDownloads = new Map(); // key -> { promise, waiters, tmpBase }

async function ytdlpDownloadResponse(videoId, fp, formatArgs, signal) {
  await assertNotLive(videoId);
  const key = videoId + '|' + formatArgs.join(' ');
  let entry = inflightDownloads.get(key);
  if (!entry) {
    const tmpBase = `ytp-dl-${videoId}-${Date.now()}`;
    const tmp = `${tmpdir()}/${tmpBase}.mp4`;
    const ctl = new AbortController();
    entry = { waiters: 0, tmpBase, ctl };
    entry.promise = withSaveSlot(() => {
      if (ctl.signal.aborted) throw new Error('save cancelled');
      return runYtdlpResilient([
        `https://www.youtube.com/watch?v=${videoId}`,
        '--no-warnings', '--no-playlist',
        ...formatArgs,
        '--limit-rate', DOWNLOAD_RATE,
        '-o', tmp,
      ], { signal: ctl.signal });
    }).then(() => ({ tmp, size: statSync(tmp).size }));
    inflightDownloads.set(key, entry);
  }
  entry.waiters++;
  // Only abort the shared yt-dlp when EVERY waiter has gone away.
  let gone = false;
  const leave = () => { if (gone) return; gone = true; if (--entry.waiters <= 0) { entry.ctl.abort(); } };
  if (signal) signal.addEventListener('abort', leave, { once: true });

  let size, fd;
  try {
    const res = await entry.promise;
    size = res.size;
    // Open the fd BEFORE the sweep unlinks: on Linux the data stays
    // readable until the fd closes, so the temp file cleans itself up even
    // if the client disconnects mid-transfer.
    fd = openSync(res.tmp, 'r');
  } finally {
    if (signal) signal.removeEventListener('abort', leave);
    if (!gone) { gone = true; entry.waiters--; }
    if (entry.waiters <= 0 && inflightDownloads.get(key) === entry) {
      inflightDownloads.delete(key);
      // Sweep everything yt-dlp may have left under this run's unique
      // prefix: the output itself, .part partials, and .fNNN single-format
      // intermediates (left when ffmpeg is missing — yt-dlp then downloads
      // the streams separately, exits 0 without merging, and statSync above
      // throws on the absent merged file).
      for (const name of readdirSync(tmpdir())) {
        if (name.startsWith(entry.tmpBase)) {
          try { unlinkSync(`${tmpdir()}/${name}`); } catch { /* already gone */ }
        }
      }
    }
  }
  const stream = createReadStream('', { fd });

  if (fp) recordVideoAccess(fp, { id: videoId }).catch(() => {});

  return new Response(Readable.toWeb(stream), {
    status: 200,
    headers: {
      'Content-Type':        'video/mp4',
      'Content-Length':      String(size),
      'Content-Disposition': `attachment; filename="${videoId}.mp4"`,
      'Cache-Control':       'no-store',
      'Access-Control-Allow-Origin': '*',
    },
  });
}

// "Edit & download": fetch the source with yt-dlp (muxed up to 720p, same as
// the mux path), then run ffmpeg to KEEP only the requested segments and
// concatenate them into one continuous mp4 — the user's custom cut. The result
// is streamed to the browser exactly like a normal save, so OPFS stores it
// under the caller-chosen custom id. Every temp file is swept afterwards.
async function ytdlpEditedDownloadResponse(videoId, fp, keep, signal) {
  await assertNotLive(videoId);
  const tmpBase = `ytp-edit-${videoId}-${Date.now()}`;
  const srcTmp  = `${tmpdir()}/${tmpBase}.src.mp4`;
  const outTmp  = `${tmpdir()}/${tmpBase}.out.mp4`;
  let size, fd;
  try {
    // 1) Grab the full source (video+audio merged) so ffmpeg has both streams.
    await withSaveSlot(() => runYtdlpResilient([
      `https://www.youtube.com/watch?v=${videoId}`,
      '--no-warnings', '--no-playlist',
      '-f', 'bv*[height<=720][ext=mp4]+ba[ext=m4a]/bv*[height<=720]+ba/b[ext=mp4]/b',
      '--merge-output-format', 'mp4',
      '--limit-rate', DOWNLOAD_RATE,
      '-o', srcTmp,
    ], { signal }));
    // 2) Trim + concat the keep segments into the final custom video.
    await runFfmpeg([
      '-y', '-hide_banner', '-loglevel', 'error',
      '-i', srcTmp,
      ...buildTrimArgs(keep),
      outTmp,
    ]);
    size = statSync(outTmp).size;
    fd = openSync(outTmp, 'r');
  } finally {
    for (const name of readdirSync(tmpdir())) {
      if (name.startsWith(tmpBase)) {
        try { unlinkSync(`${tmpdir()}/${name}`); } catch { /* already gone */ }
      }
    }
  }
  const stream = createReadStream('', { fd });

  if (fp) recordVideoAccess(fp, { id: videoId }).catch(() => {});

  return new Response(Readable.toWeb(stream), {
    status: 200,
    headers: {
      'Content-Type':        'video/mp4',
      'Content-Length':      String(size),
      'Content-Disposition': `attachment; filename="${videoId}-edited.mp4"`,
      'Cache-Control':       'no-store',
      'Access-Control-Allow-Origin': '*',
    },
  });
}

// GET /api/download/:videoId
// Downloads the video server-side via yt-dlp and streams the finished file
// to the browser so OPFS can store it. The browser never contacts YouTube
// CDN directly (CORS would block it).
app.get('/api/download/:videoId', async (c) => {
  const videoId = (c.req.param('videoId') || '').replace(/[/\\:?<>|*"]/g, '').trim();
  if (!videoId) return c.json({ ok: false, error: 'missing videoId' }, 400);
  const fp = c.req.query('fp');

  // ?edit=1&keep=s-e,s-e — "Edit & download" path: download the source, then
  // ffmpeg-trim it to the requested keep segments and stream the custom cut.
  // Requires ffmpeg; there is no progressive fallback because the whole point
  // is the server-side edit. Invalid/empty keep params are rejected up front.
  if (c.req.query('edit') === '1') {
    const keep = parseKeepParam(c.req.query('keep') || '');
    if (!keep.length) return c.json({ ok: false, error: 'missing or invalid keep segments' }, 400);
    try {
      return await ytdlpEditedDownloadResponse(videoId, fp, keep, c.req.raw.signal);
    } catch (err) {
      return c.json({ ok: false, error: err.message }, 500);
    }
  }

  // ?mux=1 — "Save before playing" path: bestvideo up to 720p PLUS bestaudio
  // compiled into one mp4 with ffmpeg on the server. Falls back to the
  // progressive single-file save below when ffmpeg is missing or the merge
  // fails.
  if (c.req.query('mux') === '1') {
    try {
      return await ytdlpDownloadResponse(videoId, fp, [
        '-f', 'bv*[height<=720][ext=mp4]+ba[ext=m4a]/bv*[height<=720]+ba/b[ext=mp4]/b',
        '--merge-output-format', 'mp4',
      ], c.req.raw.signal);
    } catch (err) {
      console.warn(`[ytplayer] mux download failed for ${videoId}, falling back to progressive:`, err.message);
    }
  }

  // Default save — best progressive (audio+video single-file) format when
  // one exists, otherwise merge bestvideo (≤720p) + bestaudio with ffmpeg.
  // YouTube now serves many videos with NO progressive format at all, which
  // made the old progressive-only selector fail every save with
  // "Requested format is not available".
  try {
    return await ytdlpDownloadResponse(videoId, fp, [
      '-f', 'bestvideo[ext=mp4][acodec!=none]/bestvideo[acodec!=none]/best[ext=mp4][acodec!=none]/'
          + 'bv*[height<=720][ext=mp4]+ba[ext=m4a]/bv*[height<=720]+ba/b',
      '--merge-output-format', 'mp4',
    ], c.req.raw.signal);
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// ============================================================================
// Online profiles — named cross-device sync. The NAME IS THE PASSKEY:
// anyone who knows it can load and overwrite that profile, so clients are
// encouraged to use the random generator. No other auth by design.
// ============================================================================
const PROFILE_NAME_RE = /^[A-Za-z0-9][A-Za-z0-9_-]{2,39}$/;
const PROFILE_MAX_BYTES = 2_000_000; // full data blob; typical payloads are ~KBs

const RAND_ADJ  = ['amber', 'brave', 'calm', 'coral', 'crimson', 'dusty', 'gentle', 'golden',
                   'hidden', 'ivory', 'jade', 'lunar', 'mellow', 'misty', 'noble', 'quiet',
                   'rapid', 'silver', 'solar', 'stormy', 'swift', 'velvet', 'wild', 'zesty'];
const RAND_NOUN = ['falcon', 'harbor', 'willow', 'ember', 'canyon', 'meadow', 'otter', 'pine',
                   'raven', 'reef', 'sparrow', 'summit', 'thicket', 'tundra', 'brook', 'cedar',
                   'dune', 'fjord', 'glade', 'heron', 'lagoon', 'maple', 'prairie', 'wren'];
function randomProfileName() {
  const a = RAND_ADJ[Math.floor(Math.random() * RAND_ADJ.length)];
  const n = RAND_NOUN[Math.floor(Math.random() * RAND_NOUN.length)];
  return `${a}-${n}-${1000 + Math.floor(Math.random() * 9000)}`;
}

// POST /api/profile/create
// Body: { name?, data? } — empty/absent name asks the server to generate a
// unique random one. Fails with 409 when the requested name is taken.
app.post('/api/profile/create', async (c) => {
  let body;
  try { body = await c.req.json(); } catch { return c.json({ ok: false, error: 'invalid JSON' }, 400); }

  let name = (body.name || '').trim().toLowerCase();
  const dataJson = JSON.stringify(body.data && typeof body.data === 'object' ? body.data : {});
  if (dataJson.length > PROFILE_MAX_BYTES) return c.json({ ok: false, error: 'profile data too large' }, 413);

  try {
    if (name) {
      if (!PROFILE_NAME_RE.test(name)) {
        return c.json({ ok: false, error: 'invalid name — 3-40 characters: letters, digits, - or _' }, 400);
      }
      if (!(await createProfile(name, dataJson))) {
        return c.json({ ok: false, error: `“${name}” is already taken — pick another name` }, 409);
      }
    } else {
      let created = false;
      for (let tries = 0; tries < 20 && !created; tries++) {
        name = randomProfileName();
        created = await createProfile(name, dataJson);
      }
      if (!created) return c.json({ ok: false, error: 'could not generate a unique name — try again' }, 500);
    }
    const row = await getProfile(name);
    return c.json({ ok: true, name, updatedAt: row ? row.updatedAt : 0 });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// GET /api/profile/load?name=<name>
app.get('/api/profile/load', async (c) => {
  const name = (c.req.query('name') || '').trim().toLowerCase();
  if (!name) return c.json({ ok: false, error: 'missing name' }, 400);
  try {
    const row = await getProfile(name);
    if (!row) return c.json({ ok: false, error: 'profile not found' }, 404);
    let data = {};
    try { data = JSON.parse(row.data || '{}'); } catch { /* corrupt blob — hand back empty */ }
    return c.json({ ok: true, name, data, updatedAt: row.updatedAt });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// POST /api/profile/save
// Body: { name, data } — updates an EXISTING profile only (404 otherwise).
app.post('/api/profile/save', async (c) => {
  let body;
  try { body = await c.req.json(); } catch { return c.json({ ok: false, error: 'invalid JSON' }, 400); }

  const name = (body.name || '').trim().toLowerCase();
  if (!name) return c.json({ ok: false, error: 'missing name' }, 400);
  const dataJson = JSON.stringify(body.data && typeof body.data === 'object' ? body.data : {});
  if (dataJson.length > PROFILE_MAX_BYTES) return c.json({ ok: false, error: 'profile data too large' }, 413);

  try {
    if (!(await saveProfile(name, dataJson))) {
      return c.json({ ok: false, error: 'profile not found' }, 404);
    }
    const row = await getProfile(name);
    return c.json({ ok: true, updatedAt: row ? row.updatedAt : 0 });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// ============================================================================
// Shared playlists — single-playlist sharing via a 10-character code.
// ============================================================================
const PLAYLIST_CODE_CHARS = 'abcdefghijklmnopqrstuvwxyz0123456789';
function randomPlaylistCode() {
  let code = '';
  for (let i = 0; i < 10; i++) {
    code += PLAYLIST_CODE_CHARS[Math.floor(Math.random() * PLAYLIST_CODE_CHARS.length)];
  }
  return code;
}

// A shared playlist is the ONLY path by which one user's video objects reach
// another user's DOM, so the blob is rebuilt field-by-field here rather than
// stored as sent. Anything not in this whitelist is dropped, and the two fields
// that end up in HTML attributes (thumbnail, channelUrl) must parse as http(s)
// URLs — otherwise a crafted `thumbnail` closes the src attribute and injects
// markup on the importing device. `custom` edits are dropped outright: their
// media only exists in the sharer's OPFS cache, so they are unplayable anywhere
// else and would just render as permanently broken entries.
const SHARED_STR_MAX = 300;
function safeStr(v, max = SHARED_STR_MAX) {
  return typeof v === 'string' ? v.slice(0, max) : '';
}
function safeHttpUrl(v) {
  if (typeof v !== 'string' || v.length > 2000) return '';
  try {
    const u = new URL(v);
    return (u.protocol === 'http:' || u.protocol === 'https:') ? u.href : '';
  } catch { return ''; }
}
function sanitizeSharedVideo(v) {
  if (!v || typeof v !== 'object') return null;
  const id = safeStr(v.id, 64);
  if (!id || v.custom) return null;
  const duration = Number(v.duration);
  return {
    id,
    title:      safeStr(v.title),
    channel:    safeStr(v.channel),
    channelId:  safeStr(v.channelId, 64),
    channelUrl: safeHttpUrl(v.channelUrl),
    duration:   Number.isFinite(duration) && duration >= 0 ? duration : 0,
    thumbnail:  safeHttpUrl(v.thumbnail),
  };
}

// POST /api/playlist/share
// Body: { playlist: { name, videos: [...] } }
app.post('/api/playlist/share', async (c) => {
  let body;
  try { body = await c.req.json(); } catch { return c.json({ ok: false, error: 'invalid JSON' }, 400); }

  const pl = body?.playlist;
  if (!pl || typeof pl !== 'object') {
    return c.json({ ok: false, error: 'missing playlist' }, 400);
  }

  const name = typeof pl.name === 'string' ? pl.name.trim() : '';
  if (!name || name.length > 200) {
    return c.json({ ok: false, error: 'invalid name — must be non-empty and <= 200 chars' }, 400);
  }

  if (!Array.isArray(pl.videos) || pl.videos.length < 1 || pl.videos.length > 500) {
    return c.json({ ok: false, error: 'invalid videos — must be an array of 1 to 500 videos' }, 400);
  }

  const videos = pl.videos.map(sanitizeSharedVideo).filter(Boolean);
  if (!videos.length) return c.json({ ok: false, error: 'no usable videos in that playlist' }, 400);

  const dataJson = JSON.stringify({ name, videos });
  if (dataJson.length > PROFILE_MAX_BYTES) {
    return c.json({ ok: false, error: 'playlist data too large' }, 413);
  }

  try {
    let code = '';
    let created = false;
    for (let tries = 0; tries < 20 && !created; tries++) {
      code = randomPlaylistCode();
      created = await createSharedPlaylist(code, dataJson);
    }
    if (!created) {
      return c.json({ ok: false, error: 'could not generate a unique share code — try again' }, 500);
    }
    return c.json({ ok: true, code });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// GET /api/playlist/shared?code=<code>
app.get('/api/playlist/shared', async (c) => {
  const code = (c.req.query('code') || '').trim().toLowerCase();
  if (!code) return c.json({ ok: false, error: 'missing code' }, 400);

  try {
    const row = await getSharedPlaylist(code);
    if (!row) {
      return c.json({ ok: false, error: 'shared playlist not found' }, 404);
    }
    let pl = null;
    try { pl = JSON.parse(row.data || '{}'); } catch { /* corrupt blob */ }
    if (!pl || typeof pl !== 'object' || !pl.name || !Array.isArray(pl.videos)) {
      return c.json({ ok: false, error: 'shared playlist not found' }, 404);
    }
    return c.json({
      ok: true,
      code,
      playlist: { name: pl.name, videos: pl.videos },
      createdAt: row.createdAt,
    });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

function isYoutubeHost(hostname) {
  const h = (hostname || '').toLowerCase();
  return h === 'youtube.com' || h.endsWith('.youtube.com') ||
         h === 'youtu.be' || h.endsWith('.youtu.be');
}

function isValidYoutubeUrl(rawUrl) {
  if (typeof rawUrl !== 'string' || !rawUrl.trim()) return false;
  try {
    const u = new URL(rawUrl.trim());
    return (u.protocol === 'http:' || u.protocol === 'https:') && isYoutubeHost(u.hostname);
  } catch {
    return false;
  }
}

// GET /api/playlist/expand?url=<youtube playlist url>
// Expands a YouTube playlist URL into slim video cards without resolving streams.
app.get('/api/playlist/expand', async (c) => {
  const url = (c.req.query('url') || '').trim();
  if (!url || !isValidYoutubeUrl(url)) {
    return c.json({ ok: false, error: 'invalid YouTube URL' }, 400);
  }

  try {
    const out = await runYtdlpResilient([
      url,
      '--dump-json', '--flat-playlist',
      '--no-warnings', '--ignore-errors',
      '--playlist-end', '201',
    ]);
    const parsed = parseCards(out);
    let title = '';
    for (const line of out.split('\n')) {
      const t = line.trim();
      if (!t) continue;
      try {
        const j = JSON.parse(t);
        title = title || pick(j, 'playlist_title', 'playlist');
        if (title) break;
      } catch { /* skip */ }
    }
    const truncated = parsed.length > 200;
    const entries = parsed.slice(0, 200);
    const resp = {
      ok: true,
      title: title || '',
      entries,
    };
    if (truncated) resp.truncated = true;
    return c.json(resp);
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 502);
  }
});

// POST /api/user/sync
// Body: { fingerprint, playlists?, recentVideo?, appVersion? }
app.post('/api/user/sync', async (c) => {
  let body;
  try { body = await c.req.json(); } catch { return c.json({ ok: false, error: 'invalid JSON' }, 400); }

  const fp = (body.fingerprint || '').trim();
  if (!fp) return c.json({ ok: false, error: 'missing fingerprint' }, 400);

  try {
    await upsertUser({ fingerprint: fp, appVersion: body.appVersion, playlists: body.playlists });
    if (body.recentVideo && body.recentVideo.id) {
      await recordVideoAccess(fp, body.recentVideo);
    }
    return c.json({ ok: true });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// GET /api/user/data?fp=<fingerprint>
app.get('/api/user/data', async (c) => {
  const fp = (c.req.query('fp') || '').trim();
  if (!fp) return c.json({ ok: false, error: 'missing fingerprint' }, 400);
  try {
    const userData = await getUserData(fp);
    return c.json({ ok: true, ...userData, version: APP_VERSION });
  } catch (err) {
    return c.json({ ok: false, error: err.message }, 500);
  }
});

// ============================================================================
// GET /sw.js — serve the service worker with BUILD_TAG injected
//
// The raw sw.js file contains the placeholder `__BUILD_TAG__` which is
// replaced here with the actual BUILD_TAG string so the SW's cache name
// tracks the deployment automatically — no manual version bump needed.
// Served with no-store cache headers so browsers always re-fetch it and
// pick up the substituted value rather than a browser-cached stale copy.
// ============================================================================
let _swSource = null;
app.get('/sw.js', (c) => {
  if (!_swSource) {
    try {
      _swSource = readFileSync('./public/sw.js', 'utf8');
    } catch {
      return c.text('Service worker not found', 404);
    }
  }
  // Inject the build tag: replace the whole fallback expression with the
  // real value. Matched by REGEX, not an exact string — an exact match broke
  // the moment the fallback literal in sw.js was bumped ('v1.0.3' → 'v1.0.4'),
  // after which the replacement silently did nothing, the SW version froze,
  // and clients never saw another update no matter how many times we deployed.
  const src = _swSource.replace(
    /typeof __BUILD_TAG__ !== 'undefined' \? __BUILD_TAG__ : '[^']*'/,
    JSON.stringify(BUILD_TAG)
  );
  if (src === _swSource) {
    console.error('[sw] BUILD_TAG injection failed — placeholder not found in sw.js');
  }
  return c.text(src, 200, {
    'Content-Type': 'application/javascript; charset=utf-8',
    'Cache-Control': 'no-store, no-cache, must-revalidate',
  });
});

// ============================================================================
// Static files — serve the frontend/public directory
// Must come AFTER all /api routes so API takes priority
// ============================================================================
app.use('/*', serveStatic({ root: './public' }));
// SPA fallback — return index.html for any unmatched path
app.get('/*', serveStatic({ path: './public/index.html' }));

// ============================================================================
// Boot
// ============================================================================
async function main() {
  await initDb();
  console.log(`[ytplayer] DB ready`);
  console.log(`[ytplayer] Starting on port ${PORT}`);

  // Bun.serve is the native Bun HTTP server
  Bun.serve({
    port: PORT,
    fetch: app.fetch,
    // Default is 10s, which killed /api/download proxy streams whenever the
    // connection went idle mid-transfer. 240s then killed every save whose
    // server-side yt-dlp phase (no bytes sent yet) ran longer than 4 min —
    // long videos at the rate cap — and the client retried in a loop.
    // 0 disables the idle timeout entirely (verified with a 300s request);
    // runaway downloads are bounded by MAX_SAVE_SECONDS + kill-on-disconnect.
    idleTimeout: 0,
  });

  console.log(`[ytplayer] Listening → http://localhost:${PORT}`);
}

main().catch((err) => {
  console.error('[ytplayer] fatal:', err);
  process.exit(1);
});