refactor(auto-thumbnail): [PKG-AUTO-THUMB-03] type internal extraction contracts

packages/artplayer-plugin-auto-thumbnail/src/index.ts

@@ -0,0 +1,46 @@
+import type { Cleanup, ThumbnailHost, ThumbnailOptions } from './types'
+import extract from './extraction'
+import { readOptions } from './options'
+import createSession, { cleanupAll } from './session'
+
+export default function artplayerPluginAutoThumbnail(option: ThumbnailOptions) {
+  return async (art: ThumbnailHost) => {
+    const report = (error: unknown) => console.warn('ArtPlayer auto-thumbnail failed:', error)
+    const session = createSession((config) => {
+      art.thumbnails = config
+    }, report)
+    const subscriptions: Cleanup[] = []
+    const onMetadata = () => {
+      const job = session.start()
+      if (job) {
+        job.guard(() => {
+          const config = readOptions(option, () => art.option.url)
+          if (job.active())
+            extract(job, config)
+        })()
+      }
+    }
+    const onDestroy = () => {
+      const actions = subscriptions.splice(0)
+      const result = cleanupAll([session.destroy, ...actions])
+      if (result.failed)
+        report(result.failure)
+    }
+    try {
+      const events: [string, Cleanup][] = [['destroy', onDestroy], ['restart', session.cancel], ['video:loadedmetadata', onMetadata]]
+      for (const [name, callback] of events) {
+        if (session.closed)
+          break
+        subscriptions.push(() => art.off(name, callback))
+        art.on(name, callback)
+        if (session.closed)
+          art.off(name, callback)
+      }
+    }
+    catch (error) {
+      onDestroy()
+      throw error
+    }
+    return { name: 'artplayerPluginAutoThumbnail' }
+  }
+}