refactor(iframe): [PKG-IFRAME-03] scope requests to active documents

packages/artplayer-tool-iframe/src/child-session.ts

@@ -0,0 +1,92 @@
+import type { Packet } from './requests'
+import { sessionMetadata, sessionType, withSession } from './protocol'
+
+interface ChildSession {
+  owner: Document
+  id: string
+  acknowledged: boolean
+  lifecycle: boolean
+  receivers: Set<(event: MessageEvent<Packet>) => void>
+}
+
+let session: ChildSession | undefined
+
+export function prepareChildSession(): void {
+  if (session?.owner === window.document && session)
+    return
+  const random = new Uint32Array(4)
+  if (window.crypto?.getRandomValues)
+    window.crypto.getRandomValues(random)
+  else
+    random.forEach((_, index) => random[index] = Math.floor(Math.random() * 0x100000000))
+  session = { owner: window.document, id: `${Date.now()}-${Array.from(random).join('-')}`, acknowledged: false, lifecycle: false, receivers: new Set() }
+}
+
+export function childEnvelope(packet: Packet): Packet {
+  if (session && (packet.type === 'inject' || session.acknowledged))
+    return withSession(packet, session.id, packet.type === 'inject' ? 'inject' : 'message')
+  return packet
+}
+
+export function consumeChildSession(packet: Packet): boolean {
+  const metadata = sessionMetadata(packet)
+  if (!metadata)
+    return false
+  if (packet.type === sessionType) {
+    if (session && metadata.document === session.id && metadata.phase === 'ack')
+      session.acknowledged = true
+    return true
+  }
+  return !session || metadata.document !== session.id
+}
+
+export function connectChildSession(receiver: (event: MessageEvent<Packet>) => void): void {
+  const current = session!
+  const added = !current.receivers.has(receiver)
+  const installing = !current.lifecycle
+  const notify = (phase: 'leave' | 'resume' | 'fragment', data?: unknown) => {
+    if (!current.acknowledged)
+      return
+    try {
+      window.parent.postMessage(withSession({ type: sessionType, data, id: 0 }, current.id, phase), '*')
+    }
+    catch {
+      // The parent may have disappeared; this private lifecycle notification is best effort.
+    }
+  }
+  const leave = () => notify('leave')
+  const fragment = () => notify('fragment', window.location.href)
+  const resume = (event: PageTransitionEvent) => {
+    if (event.persisted)
+      notify('resume')
+  }
+  try {
+    window.addEventListener('message', receiver)
+    current.receivers.add(receiver)
+    if (!installing)
+      return
+    window.addEventListener('pagehide', leave)
+    window.addEventListener('pageshow', resume)
+    window.addEventListener('hashchange', fragment)
+    current.lifecycle = true
+  }
+  catch (error) {
+    const cleanups: (() => void)[] = []
+    if (installing) {
+      cleanups.push(() => window.removeEventListener('pagehide', leave))
+      cleanups.push(() => window.removeEventListener('pageshow', resume))
+      cleanups.push(() => window.removeEventListener('hashchange', fragment))
+    }
+    if (added)
+      cleanups.push(() => window.removeEventListener('message', receiver))
+    for (const cleanup of cleanups) {
+      try {
+        cleanup()
+      }
+      catch { /* Preserve the acquisition error while releasing the other listeners. */ }
+    }
+    if (added)
+      current.receivers.delete(receiver)
+    throw error
+  }
+}