refactor(core): CORE-09 isolate source operations and settle cancelled switches

test/types/source.ts

@@ -0,0 +1,36 @@
+import type { CanvasMedia, NativeMedia } from '../../packages/artplayer/src/media/types'
+import type { SourceMedia, SwitchHost, UrlHost } from '../../packages/artplayer/src/source/types'
+import switchMix from '../../packages/artplayer/src/player/switchMix'
+import urlMix from '../../packages/artplayer/src/player/urlMix'
+
+declare const native: NativeMedia
+declare const canvas: CanvasMedia
+const sourceMedia: SourceMedia[] = [native, canvas]
+void sourceMedia
+
+declare const switching: SwitchHost
+switchMix(switching)
+const pending: Promise<void> = switching.switchQuality('movie.mp4')
+void pending
+switching.switch = 'movie.mp4'
+// @ts-expect-error Source URLs remain strings.
+switching.switchUrl(42)
+// @ts-expect-error Switching does not resolve with a media element or success boolean.
+const wrong: Promise<boolean> = switching.switchUrl('movie.mp4')
+void wrong
+
+interface CustomHost extends UrlHost<CanvasMedia, CustomHost> {
+  extension: number
+}
+declare const custom: CustomHost
+custom.option.customType.canvas = function (video, url, art) {
+  this satisfies CustomHost
+  const owner: CustomHost = art
+  const surface: HTMLCanvasElement = video
+  const source: string = url
+  void [owner, surface, source]
+  // @ts-expect-error A canvas proxy is not a native video element.
+  const wrongMedia: HTMLVideoElement = video
+  void wrongMedia
+}
+urlMix<CanvasMedia, CustomHost>(custom)