feat(baoyu-youtube-transcript): add yt-dlp fallback and modularize codebase

Retry with alternate InnerTube client identities when YouTube returns anti-bot responses, then fall back to yt-dlp when available. Split monolithic main.ts into typed modules (youtube, transcript, storage, shared, types) and add unit tests.
2026-07-23 18:49:48 +08:00 · 2026-03-24 20:59:04 -05:00
parent 7c995fcc24
commit 09ce80357f
8 changed files with 1320 additions and 700 deletions
@@ -0,0 +1,125 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { findTranscript, parseTranscriptJson3, parseWebVtt } from "./transcript.ts";
+import { buildTranscriptListFromYtDlp, resolveVideoSource, selectYtDlpTrack } from "./youtube.ts";
+
+test("selectYtDlpTrack prefers json3 over xml and vtt", () => {
+  const track = selectYtDlpTrack([
+    { ext: "vtt", url: "https://example.com/subs.vtt" },
+    { ext: "srv3", url: "https://example.com/subs.srv3" },
+    { ext: "json3", url: "https://example.com/subs.json3" },
+  ]);
+
+  assert.equal(track?.ext, "json3");
+});
+
+test("buildTranscriptListFromYtDlp keeps manual and generated tracks separate", () => {
+  const transcripts = buildTranscriptListFromYtDlp({
+    subtitles: {
+      en: [
+        { ext: "json3", url: "https://example.com/en.json3", name: "English" },
+      ],
+    },
+    automatic_captions: {
+      "zh-Hans": [
+        { ext: "json3", url: "https://example.com/zh.json3", name: "Chinese (Simplified)" },
+      ],
+    },
+  });
+
+  assert.equal(transcripts.length, 2);
+  assert.equal(transcripts[0].isGenerated, false);
+  assert.equal(transcripts[1].isGenerated, true);
+  assert.equal(transcripts[0].translationLanguages[0]?.languageCode, "zh-Hans");
+
+  const translated = findTranscript(transcripts, ["zh-Hans"], false, false);
+  assert.equal(translated.languageCode, "zh-Hans");
+  assert.equal(translated.isGenerated, true);
+});
+
+test("parseTranscriptJson3 reads youtube timedtext json3 payloads", () => {
+  const snippets = parseTranscriptJson3(JSON.stringify({
+    events: [
+      {
+        tStartMs: 80,
+        dDurationMs: 3120,
+        segs: [{ utf8: "hello\nworld" }],
+      },
+      {
+        tStartMs: 4000,
+        dDurationMs: 1800,
+        segs: [{ utf8: "again" }],
+      },
+    ],
+  }));
+
+  assert.deepEqual(snippets, [
+    { text: "hello world", start: 0.08, duration: 3.12 },
+    { text: "again", start: 4, duration: 1.8 },
+  ]);
+});
+
+test("parseWebVtt strips tags and cue settings", () => {
+  const snippets = parseWebVtt(`WEBVTT
+
+00:00:00.080 --> 00:00:03.200 align:start position:0%
+<c.colorE5E5E5>Hello</c> world
+
+00:00:04.000 --> 00:00:05.800
+Again
+`);
+
+  assert.equal(snippets.length, 2);
+  assert.equal(snippets[0].text, "Hello world");
+  assert.equal(snippets[0].start, 0.08);
+  assert.equal(snippets[0].duration, 3.12);
+  assert.equal(snippets[1].text, "Again");
+  assert.equal(snippets[1].start, 4);
+  assert.equal(Number(snippets[1].duration.toFixed(1)), 1.8);
+});
+
+test("resolveVideoSource prefers primary InnerTube result before fallback", async () => {
+  let fallbackCalled = false;
+  const source = await resolveVideoSource(
+    "video12345ab",
+    async () => ({ kind: "innertube", data: { videoDetails: { title: "Primary" } }, transcripts: [] }),
+    () => {
+      fallbackCalled = true;
+      return {
+        subtitles: {
+          en: [{ ext: "json3", url: "https://example.com/en.json3", name: "English" }],
+        },
+      };
+    },
+    () => {}
+  );
+
+  assert.equal(source.kind, "innertube");
+  assert.equal(fallbackCalled, false);
+});
+
+test("resolveVideoSource falls back to yt-dlp only after fallback-eligible errors", async () => {
+  let fallbackCalled = false;
+  const source = await resolveVideoSource(
+    "video12345ab",
+    async () => {
+      const error = new Error("Request blocked for video12345ab: bot detected");
+      (error as Error & { code?: string }).code = "BOT_DETECTED";
+      throw error;
+    },
+    () => {
+      fallbackCalled = true;
+      return {
+        automatic_captions: {
+          en: [{ ext: "json3", url: "https://example.com/en.json3", name: "English (auto-generated)" }],
+        },
+      };
+    },
+    () => {}
+  );
+
+  assert.equal(source.kind, "yt-dlp");
+  assert.equal(fallbackCalled, true);
+  assert.equal(source.transcripts[0].languageCode, "en");
+});