From 785e903e1e8679eef6a1c1e5ec0c42d606fec912 Mon Sep 17 00:00:00 2001
From: Jonathan Sykes <telemagnadon@gmail.com>
Date: Sun, 11 Oct 2026 03:57:02 +0800
Subject: [PATCH] Load the whole song into the browser for the lyrics editor so
 audio no longer stops

---
 frontend/admin.html        | 71 +++++++++++++++++++++++++++++++++++---
 tests/admin-lyrics.spec.js | 15 ++++++++
 2 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/frontend/admin.html b/frontend/admin.html
index 1195045..8d14b0b 100644
--- a/frontend/admin.html
+++ b/frontend/admin.html
@@ -572,6 +572,7 @@
   <nav class="nav" id="tabsBottom" role="tablist"></nav>
 </div>
 
+<script src="opfs.js"></script>
 <script src="download-actions.js"></script>
 <script src="lyrics-core.js"></script>
 <script>
@@ -1165,20 +1166,82 @@
     }
   }
 
-  function initAudio(id, streams) {
-    const url = (streams.data && streams.data.audioUrl) || ((streams.data && streams.data.qualities || []).find((q) => q.hasAudio) || {}).url || '';
+  /* The editor plays a COMPLETE local copy, never a live stream (a stream can
+     stall or expire mid-song). Order: the same saved video the player uses
+     (OPFS) → an audio-only copy kept for admin use (Cache Storage) → fetch the
+     audio-only file from the server once and keep it. */
+  const ADMIN_AUDIO_CACHE = 'ytp-admin-audio';
+  async function adminAudioBlobUrl(id, streams, onProgress) {
+    try {
+      if (window.OPFS && OPFS.isSupported() && await OPFS.hasVideo(id)) {
+        const u = await OPFS.getFileUrl(id);
+        if (u) return u;
+      }
+    } catch { /* fall through */ }
+    const key = `/admin-audio/${encodeURIComponent(id)}`;
+    let cache = null;
+    try { cache = await caches.open(ADMIN_AUDIO_CACHE); } catch { /* no Cache Storage */ }
+    if (cache) {
+      const hit = await cache.match(key).catch(() => null);
+      if (hit) return URL.createObjectURL(await hit.blob());
+    }
+    const d = (streams && streams.data) || {};
+    const sources = [`/api/media/${encodeURIComponent(id)}?a=1`,
+      d.audioUrl || ((d.qualities || []).find((q) => q.hasAudio) || {}).url || ''].filter(Boolean);
+    for (const src of sources) {
+      for (let attempt = 0; attempt < 2; attempt++) {
+        try {
+          const r = await fetch(src, { credentials: 'same-origin' });
+          if (!r.ok) break;
+          const total = Number(r.headers.get('content-length')) || 0;
+          const reader = r.body.getReader(); const parts = []; let got = 0;
+          for (;;) {
+            const { done, value } = await reader.read();
+            if (done) break;
+            parts.push(value); got += value.length;
+            if (onProgress) onProgress(got, total);
+          }
+          if (total && got < total) throw new Error('short read');
+          const blob = new Blob(parts, { type: r.headers.get('content-type') || 'audio/mp4' });
+          if (blob.size < 1024) break;
+          if (cache) await cache.put(key, new Response(blob, { headers: { 'content-type': blob.type } })).catch(() => {});
+          return URL.createObjectURL(blob);
+        } catch { await new Promise((ok) => setTimeout(ok, 800)); }
+      }
+    }
+    return '';
+  }
+
+  // Audio status shares the #msg line with other messages: only write when it
+  // is empty or still showing our own text, and never clobber someone else's.
+  function audioSay(text, cls) {
+    const el = $('msg'), cur = el.textContent;
+    if (cur && cur !== LE.audioMsg) return;
+    LE.audioMsg = text; say(text, cls);
+  }
+
+  async function initAudio(id, streams) {
     if (LE.audio) { LE.audio.pause(); LE.audio.src = ''; }
+    if (LE.audioUrl) { try { URL.revokeObjectURL(LE.audioUrl); } catch {} LE.audioUrl = ''; }
     LE.audio = null;
+    const token = (LE.audioToken = (LE.audioToken || 0) + 1);
+    audioSay('Loading the full audio into the browser…');
+    const url = await adminAudioBlobUrl(id, streams, (got, total) => {
+      if (token === LE.audioToken) audioSay(total ? `Loading audio… ${Math.round(got / total * 100)}%` : `Loading audio… ${(got / 1048576).toFixed(1)} MB`);
+    });
+    if (token !== LE.audioToken || LE.id !== id) { if (url) try { URL.revokeObjectURL(url); } catch {} return; }
+    audioSay('');
     if (url) {
+      LE.audioUrl = url;
       const a = new Audio(url); a.preload = 'auto';
       a.addEventListener('timeupdate', tick); a.addEventListener('seeked', tick);
       a.addEventListener('loadedmetadata', () => { if (a.duration) { LE.dur = a.duration; $('dur').textContent = fmtT(a.duration).slice(0, -3); } draw(); });
       a.addEventListener('play', () => { TransportIcons.set($('bPlay'),'pause'); });
       a.addEventListener('pause', () => { TransportIcons.set($('bPlay'),'play'); });
-      a.addEventListener('error', () => say('No playable audio for this song on the server — you can still edit the text.', 'err'));
+      a.addEventListener('error', () => audioSay('The saved audio could not be played — reload the song to fetch it again.', 'err'));
       a.playbackRate = Number($('rate').value);
       LE.audio = a;
-    } else say('This song is not cached on the server, so there is no audio to time against.', 'err');
+    } else audioSay('No audio could be saved for this song, so there is nothing to time against.', 'err');
     $('dur').textContent = fmtT(LE.dur).slice(0, -3);
     LE.peaks = null;
     fetch(`/api/media/${id}/peaks`, { credentials: 'same-origin' }).then((r) => r.json())
diff --git a/tests/admin-lyrics.spec.js b/tests/admin-lyrics.spec.js
index 88c1ad9..5e648a8 100644
--- a/tests/admin-lyrics.spec.js
+++ b/tests/admin-lyrics.spec.js
@@ -150,3 +150,18 @@ test('player lyric editor groups Shift+Enter words and stamps their shared cue',
   const document = await text.inputValue(); expect(document).toContain('[0:00.00] Because You are God\n| You can do anything');
   expect(document).not.toContain('[0:00.00] |');
 });
+test('editor loads the whole audio into the browser once and reuses it', async ({ page }) => {
+  const wav = Buffer.alloc(44 + 16000); // 1 s of silence, 8 kHz 16-bit mono
+  wav.write('RIFF', 0); wav.writeUInt32LE(36 + 16000, 4); wav.write('WAVEfmt ', 8); wav.writeUInt32LE(16, 16);
+  wav.writeUInt16LE(1, 20); wav.writeUInt16LE(1, 22); wav.writeUInt32LE(8000, 24); wav.writeUInt32LE(16000, 28);
+  wav.writeUInt16LE(2, 32); wav.writeUInt16LE(16, 34); wav.write('data', 36); wav.writeUInt32LE(16000, 40);
+  let hits = 0;
+  await fixture(page);
+  await page.route('**/api/media/' + id + '?a=1', route => { hits++; route.fulfill({ contentType: 'audio/wav', body: wav }); });
+  await page.locator('[data-open="' + id + '"]').first().click();
+  await expect(page.locator('#dur')).toHaveText('0:01');
+  expect(hits).toBe(1);
+  await page.reload(); await page.locator('[data-open="' + id + '"]').first().click();
+  await expect(page.locator('#dur')).toHaveText('0:01');
+  expect(hits).toBe(1);
+});