refactor(multiple-subtitles): [PKG-MULTI-SUB-04] type runtime modules and vendor boundaries

packages/artplayer-plugin-multiple-subtitles/src/merge.ts

@@ -0,0 +1,33 @@
+import type { Cue, WrappedNode } from './parser'
+import type { Track, TrackOption } from './types'
+import { WebVTTParser, WebVTTSerializer } from './parser'
+
+export function parseTracks(vtts: readonly string[], subtitles: readonly TrackOption[]): Track[] {
+  const parser = new WebVTTParser()
+  return vtts.map((vtt, index) => {
+    const tree = parser.parse(vtt, 'metadata')
+    // Options and completed downloads share the same Promise.all index.
+    return { ...tree, url: subtitles[index]!.url, name: subtitles[index]!.name }
+  })
+}
+
+export function serializeTracks(trees: readonly (Track | undefined)[]): string {
+  const cues: Cue<WrappedNode>[] = []
+  for (const selected of trees) {
+    // Unknown names retain the historical TypeError at the property access below.
+    const tree = selected!
+    for (const cue of tree.cues) {
+      cues.push({
+        ...cue,
+        tree: {
+          ...cue.tree,
+          children: cue.tree.children.map(child => ({
+            ...child,
+            value: `<div class="art-subtitle-${tree.name}">${child.value}</div>`,
+          })),
+        },
+      })
+    }
+  }
+  return new WebVTTSerializer().serialize(cues)
+}