fix: Lazy unloading should not leave dangling connections (#2004)

- Closes #1992

src/components-lib/lazy-load-controller.ts

@@ -0,0 +1,102 @@
+import { ReactiveController, ReactiveControllerHost } from 'lit';
+import { LazyUnloadCondition } from '../config/schema/common/media-actions';
+
+type LazyLoadListener = (loaded: boolean) => void;
+
+export class LazyLoadController implements ReactiveController {
+  private _host: ReactiveControllerHost & HTMLElement;
+  private _documentVisible = true;
+  private _intersects = false;
+  private _loaded: boolean;
+  private _unloadConditions: LazyUnloadCondition[] | null = null;
+  private _intersectionObserver = new IntersectionObserver(
+    this._intersectionHandler.bind(this),
+  );
+  private _listeners: LazyLoadListener[] = [];
+
+  constructor(
+    host: ReactiveControllerHost & HTMLElement,
+    lazyLoad?: boolean,
+    lazyUnloadConditions?: LazyUnloadCondition[],
+  ) {
+    this._host = host;
+    this._host.addController(this);
+
+    this._loaded = !lazyLoad;
+    this._unloadConditions = lazyUnloadConditions ?? null;
+  }
+
+  public destroy(): void {
+    this._removeEventHandlers();
+    this._listeners = [];
+  }
+
+  public isLoaded(): boolean {
+    return this._loaded;
+  }
+
+  public addListener(listener: LazyLoadListener): void {
+    this._listeners.push(listener);
+  }
+
+  public removeListener(listener: LazyLoadListener): void {
+    this._listeners = this._listeners.filter((l) => l !== listener);
+  }
+
+  public removeController(): void {
+    this._host.removeController(this);
+  }
+
+  public hostConnected(): void {
+    this._addEventHandlers();
+  }
+
+  public hostDisconnected(): void {
+    this._removeEventHandlers();
+    this._setLoaded(false);
+  }
+
+  private _addEventHandlers(): void {
+    document.addEventListener('visibilitychange', this._visibilityHandler);
+    this._intersectionObserver.observe(this._host);
+  }
+
+  private _removeEventHandlers(): void {
+    document.removeEventListener('visibilitychange', this._visibilityHandler);
+    this._intersectionObserver.disconnect();
+  }
+
+  private _lazyLoadOrUnloadIfNecessary(): void {
+    const shouldBeLoaded = !this._loaded && this._documentVisible && this._intersects;
+    const shouldBeUnloaded =
+      this._loaded &&
+      ((this._unloadConditions?.includes('hidden') && !this._documentVisible) ||
+        (this._unloadConditions?.includes('unselected') && !this._intersects));
+
+    if (shouldBeLoaded) {
+      this._setLoaded(true);
+    } else if (shouldBeUnloaded) {
+      this._setLoaded(false);
+    }
+  }
+
+  private _setLoaded(loaded: boolean): void {
+    this._loaded = loaded;
+    this._notifyListeners();
+    this._host.requestUpdate();
+  }
+
+  private _notifyListeners(): void {
+    this._listeners.forEach((listener) => listener(this._loaded));
+  }
+
+  private _intersectionHandler(entries: IntersectionObserverEntry[]): void {
+    this._intersects = entries.some((entry) => entry.isIntersecting);
+    this._lazyLoadOrUnloadIfNecessary();
+  }
+
+  private _visibilityHandler = (): void => {
+    this._documentVisible = document.visibilityState === 'visible';
+    this._lazyLoadOrUnloadIfNecessary();
+  };
+}

src/components/carousel.ts

@@ -97,7 +97,18 @@ export class AdvancedCameraCardCarousel extends LitElement {
   }
 
   protected updated(changedProps: PropertyValues): void {
-    if (!this._carousel && this._refRoot.value && this._refParent.value) {
+    if (
+      !this._carousel &&
+      this._refRoot.value &&
+      this._refParent.value &&
+      // Never construct a carousel if the node is not connected. There can be a
+      // race condition between the Lit update lifecycle, and the
+      // disconnect/connect callbacks, causing a carousel to potentially be
+      // created after the node is disconnected. This could cause a dangling
+      // carousel and hold open connections that should have been closed.
+      // See: https://github.com/dermotduffy/advanced-camera-card/issues/1992
+      this.isConnected
+    ) {
       this._carousel = new CarouselController(
         this._refRoot.value,
         this._refParent.value,

src/components/live/carousel.ts

@@ -24,7 +24,6 @@ import { HomeAssistant } from '../../ha/types.js';
 import liveCarouselStyle from '../../scss/live-carousel.scss';
 import { stopEventFromActivatingCardWideActions } from '../../utils/action.js';
 import { CarouselSelected } from '../../utils/embla/carousel-controller.js';
-import { AutoLazyLoad } from '../../utils/embla/plugins/auto-lazy-load/auto-lazy-load.js';
 import AutoMediaLoadedInfo from '../../utils/embla/plugins/auto-media-loaded-info/auto-media-loaded-info.js';
 import AutoSize from '../../utils/embla/plugins/auto-size/auto-size.js';
 import { getStreamCameraID } from '../../utils/substream.js';
@@ -36,7 +35,6 @@ import '../next-prev-control.js';
 import '../ptz.js';
 import { AdvancedCameraCardPTZ } from '../ptz.js';
 import './provider.js';
-import { AdvancedCameraCardLiveProvider } from './provider.js';
 
 const ADVANCED_CAMERA_CARD_LIVE_PROVIDER = 'advanced-camera-card-live-provider';
 
@@ -140,19 +138,7 @@ export class AdvancedCameraCardLiveCarousel extends LitElement {
   }
 
   protected _getPlugins(): EmblaCarouselPlugins {
-    return [
-      AutoLazyLoad({
-        ...(this.liveConfig?.lazy_load && {
-          lazyLoadCallback: (index, slide) =>
-            this._lazyloadOrUnloadSlide('load', index, slide),
-        }),
-        lazyUnloadConditions: this.liveConfig?.lazy_unload,
-        lazyUnloadCallback: (index, slide) =>
-          this._lazyloadOrUnloadSlide('unload', index, slide),
-      }),
-      AutoMediaLoadedInfo(),
-      AutoSize(),
-    ];
+    return [AutoMediaLoadedInfo(), AutoSize()];
   }
 
   /**
@@ -217,23 +203,6 @@ export class AdvancedCameraCardLiveCarousel extends LitElement {
     }
   }
 
-  protected _lazyloadOrUnloadSlide(
-    action: 'load' | 'unload',
-    _index: number,
-    slide: Element,
-  ): void {
-    if (slide instanceof HTMLSlotElement) {
-      slide = slide.assignedElements({ flatten: true })[0];
-    }
-
-    const liveProvider = slide?.querySelector(
-      ADVANCED_CAMERA_CARD_LIVE_PROVIDER,
-    ) as AdvancedCameraCardLiveProvider | null;
-    if (liveProvider) {
-      liveProvider.load = action === 'load';
-    }
-  }
-
   protected _renderLive(
     cameraID: string,
     cameraConfig: CameraConfig,
@@ -248,7 +217,6 @@ export class AdvancedCameraCardLiveCarousel extends LitElement {
     return html`
       <div class="embla__slide">
         <advanced-camera-card-live-provider
-          ?load=${!this.liveConfig.lazy_load}
           .microphoneState=${view?.camera === cameraID
             ? this.microphoneState
             : undefined}

src/components/live/provider.ts

@@ -12,6 +12,7 @@ import { guard } from 'lit/directives/guard.js';
 import { createRef, Ref, ref } from 'lit/directives/ref.js';
 import { CameraEndpoints } from '../../camera-manager/types.js';
 import { MicrophoneState } from '../../card-controller/types.js';
+import { LazyLoadController } from '../../components-lib/lazy-load-controller.js';
 import { dispatchLiveErrorEvent } from '../../components-lib/live/utils/dispatch-live-error.js';
 import { PartialZoomSettings } from '../../components-lib/zoom/types.js';
 import { CameraConfig, LiveProvider } from '../../config/schema/cameras.js';
@@ -45,12 +46,6 @@ export class AdvancedCameraCardLiveProvider extends LitElement implements MediaP
   @property({ attribute: false })
   public liveConfig?: LiveConfig;
 
-  // Whether or not to load the video for this camera. If `false`, no contents
-  // are rendered until this attribute is set to `true` (this is useful for lazy
-  // loading).
-  @property({ attribute: true, type: Boolean })
-  public load = false;
-
   // Label that is used for ARIA support and as tooltip.
   @property({ attribute: false })
   public label = '';
@@ -74,6 +69,7 @@ export class AdvancedCameraCardLiveProvider extends LitElement implements MediaP
   protected _showStreamTroubleshooting = false;
 
   protected _refProvider: Ref<MediaPlayerElement> = createRef();
+  protected _lazyLoadController: LazyLoadController | null = null;
 
   // A note on dynamic imports:
   //
@@ -144,11 +140,23 @@ export class AdvancedCameraCardLiveProvider extends LitElement implements MediaP
   }
 
   protected willUpdate(changedProps: PropertyValues): void {
-    if (changedProps.has('load')) {
-      if (!this.load) {
-        this._isVideoMediaLoaded = false;
-        dispatchMediaUnloadedEvent(this);
-      }
+    if (
+      changedProps.has('liveConfig') ||
+      (!this._lazyLoadController && this.liveConfig)
+    ) {
+      this._lazyLoadController?.destroy();
+      this._lazyLoadController?.removeController();
+      this._lazyLoadController = new LazyLoadController(
+        this,
+        this.liveConfig?.lazy_load,
+        this.liveConfig?.lazy_unload,
+      );
+      this._lazyLoadController.addListener((loaded: boolean) => {
+        if (!loaded) {
+          this._isVideoMediaLoaded = false;
+          dispatchMediaUnloadedEvent(this);
+        }
+      });
     }
 
     if (changedProps.has('liveConfig')) {
@@ -216,7 +224,12 @@ export class AdvancedCameraCardLiveProvider extends LitElement implements MediaP
   }
 
   protected render(): TemplateResult | void {
-    if (!this.load || !this.hass || !this.liveConfig || !this.cameraConfig) {
+    if (
+      !this._lazyLoadController?.isLoaded() ||
+      !this.hass ||
+      !this.liveConfig ||
+      !this.cameraConfig
+    ) {
       return;
     }
 

src/components/viewer/carousel.ts

@@ -24,7 +24,6 @@ import { MediaLoadedInfo, MediaPlayerController } from '../../types.js';
 import { stopEventFromActivatingCardWideActions } from '../../utils/action.js';
 import { contentsChanged, setOrRemoveAttribute } from '../../utils/basic.js';
 import { CarouselSelected } from '../../utils/embla/carousel-controller.js';
-import { AutoLazyLoad } from '../../utils/embla/plugins/auto-lazy-load/auto-lazy-load.js';
 import AutoMediaLoadedInfo from '../../utils/embla/plugins/auto-media-loaded-info/auto-media-loaded-info.js';
 import AutoSize from '../../utils/embla/plugins/auto-size/auto-size.js';
 import { ResolvedMediaCache } from '../../utils/ha/resolved-media.js';
@@ -36,7 +35,6 @@ import { renderMessage } from '../message.js';
 import '../next-prev-control.js';
 import '../ptz.js';
 import './provider.js';
-import { AdvancedCameraCardViewerProvider } from './provider.js';
 
 interface MediaNeighbor {
   index: number;
@@ -137,15 +135,7 @@ export class AdvancedCameraCardViewerCarousel extends LitElement {
    * @returns A list of EmblaOptionsTypes.
    */
   protected _getPlugins(): EmblaCarouselPlugins {
-    return [
-      AutoLazyLoad({
-        ...(this.viewerConfig?.lazy_load && {
-          lazyLoadCallback: (_index, slide) => this._lazyloadSlide(slide),
-        }),
-      }),
-      AutoMediaLoadedInfo(),
-      AutoSize(),
-    ];
+    return [AutoMediaLoadedInfo(), AutoSize()];
   }
 
   /**
@@ -211,23 +201,6 @@ export class AdvancedCameraCardViewerCarousel extends LitElement {
     });
   }
 
-  /**
-   * Lazy load a slide.
-   * @param slide The slide to lazy load.
-   */
-  protected _lazyloadSlide(slide: Element): void {
-    if (slide instanceof HTMLSlotElement) {
-      slide = slide.assignedElements({ flatten: true })[0];
-    }
-
-    const viewerProvider = slide?.querySelector(
-      'advanced-camera-card-viewer-provider',
-    ) as AdvancedCameraCardViewerProvider | null;
-    if (viewerProvider) {
-      viewerProvider.load = true;
-    }
-  }
-
   /**
    * Get slides to include in the render.
    * @returns The slides to include in the render.
@@ -450,7 +423,6 @@ export class AdvancedCameraCardViewerCarousel extends LitElement {
         .viewerConfig=${this.viewerConfig}
         .resolvedMediaCache=${this.resolvedMediaCache}
         .cameraManager=${this.cameraManager}
-        .load=${!this.viewerConfig.lazy_load}
         .cardWideConfig=${this.cardWideConfig}
       ></advanced-camera-card-viewer-provider>
     </div>`;

src/components/viewer/provider.ts

@@ -11,6 +11,7 @@ import { guard } from 'lit/directives/guard.js';
 import { createRef, Ref, ref } from 'lit/directives/ref.js';
 import { CameraManager } from '../../camera-manager/manager.js';
 import { ViewManagerEpoch } from '../../card-controller/view/types.js';
+import { LazyLoadController } from '../../components-lib/lazy-load-controller.js';
 import { ZoomSettingsObserved } from '../../components-lib/zoom/types.js';
 import { handleZoomSettingsObservedEvent } from '../../components-lib/zoom/zoom-view-context.js';
 import { CardWideConfig } from '../../config/schema/types.js';
@@ -61,12 +62,6 @@ export class AdvancedCameraCardViewerProvider extends LitElement implements Medi
   @property({ attribute: false })
   public resolvedMediaCache?: ResolvedMediaCache;
 
-  // Whether or not to load the viewer media. If `false`, no contents are
-  // rendered until this attribute is set to `true` (this is useful for lazy
-  // loading).
-  @property({ attribute: false })
-  public load = false;
-
   @property({ attribute: false })
   public cameraManager?: CameraManager;
 
@@ -74,6 +69,7 @@ export class AdvancedCameraCardViewerProvider extends LitElement implements Medi
   public cardWideConfig?: CardWideConfig;
 
   protected _refProvider: Ref<MediaPlayerElement> = createRef();
+  protected _lazyLoadController: LazyLoadController | null = null;
 
   @state()
   protected _url: string | null = null;
@@ -127,7 +123,7 @@ export class AdvancedCameraCardViewerProvider extends LitElement implements Medi
       !this.media ||
       !mediaContentID ||
       !this.hass ||
-      (this.viewerConfig?.lazy_load && !this.load)
+      !this._lazyLoadController?.isLoaded()
     ) {
       return;
     }
@@ -185,15 +181,25 @@ export class AdvancedCameraCardViewerProvider extends LitElement implements Medi
 
   protected willUpdate(changedProps: PropertyValues): void {
     if (
-      changedProps.has('load') ||
+      changedProps.has('viewerConfig') ||
+      (!this._lazyLoadController && this.viewerConfig)
+    ) {
+      this._lazyLoadController?.destroy();
+      this._lazyLoadController?.removeController();
+      this._lazyLoadController = new LazyLoadController(
+        this,
+        this.viewerConfig?.lazy_load,
+      );
+      this._lazyLoadController.addListener((loaded) => loaded && this._setURL());
+    }
+
+    if (
       changedProps.has('media') ||
       changedProps.has('viewerConfig') ||
       changedProps.has('resolvedMediaCache') ||
       changedProps.has('hass')
     ) {
-      this._setURL().then(() => {
-        this.requestUpdate();
-      });
+      this._setURL();
     }
 
     if (changedProps.has('viewerConfig') && this.viewerConfig?.zoomable) {
@@ -246,7 +252,12 @@ export class AdvancedCameraCardViewerProvider extends LitElement implements Medi
   }
 
   protected render(): TemplateResult | void {
-    if (!this.load || !this.media || !this.hass || !this.viewerConfig) {
+    if (
+      !this._lazyLoadController?.isLoaded() ||
+      !this.media ||
+      !this.hass ||
+      !this.viewerConfig
+    ) {
       return;
     }
 

src/utils/embla/plugins/auto-lazy-load/auto-lazy-load.ts

@@ -1,137 +0,0 @@
-import { EmblaCarouselType, EmblaEventType } from 'embla-carousel';
-import { CreateOptionsType } from 'embla-carousel/components/Options';
-import { OptionsHandlerType } from 'embla-carousel/components/OptionsHandler';
-import { CreatePluginType, LoosePluginType } from 'embla-carousel/components/Plugins';
-import { LazyUnloadCondition } from '../../../../config/schema/common/media-actions';
-
-declare module 'embla-carousel/components/Plugins' {
-  interface EmblaPluginsType {
-    lazyload?: AutoLazyLoadType;
-  }
-}
-
-type OptionsType = CreateOptionsType<{
-  // Number of slides to lazyload left/right of selected (0 == only selected
-  // slide).
-  lazyLoadCount: number;
-  lazyUnloadConditions?: readonly LazyUnloadCondition[];
-
-  lazyLoadCallback?: (index: number, slide: HTMLElement) => void;
-  lazyUnloadCallback?: (index: number, slide: HTMLElement) => void;
-}>;
-type AutoLazyLoadOptionsType = Partial<OptionsType>;
-type AutoLazyLoadType = CreatePluginType<LoosePluginType, AutoLazyLoadOptionsType>;
-
-const defaultOptions: OptionsType = {
-  active: true,
-  breakpoints: {},
-  lazyLoadCount: 0,
-};
-
-export function AutoLazyLoad(
-  userOptions: AutoLazyLoadOptionsType = {},
-): AutoLazyLoadType {
-  let options: OptionsType;
-  let emblaApi: EmblaCarouselType;
-  let slides: HTMLElement[];
-  const lazyLoadedSlides: Set<number> = new Set();
-
-  const loadEvents: EmblaEventType[] = ['init', 'select'];
-  const unloadEvents: EmblaEventType[] = ['select'];
-
-  function init(
-    emblaApiInstance: EmblaCarouselType,
-    optionsHandler: OptionsHandlerType,
-  ): void {
-    const { mergeOptions, optionsAtMedia } = optionsHandler;
-    const allOptions = mergeOptions(defaultOptions, userOptions);
-    options = optionsAtMedia(allOptions);
-
-    emblaApi = emblaApiInstance;
-    slides = emblaApi.slideNodes();
-
-    if (options.lazyLoadCallback) {
-      loadEvents.forEach((evt) => emblaApi.on(evt, lazyLoadHandler));
-    }
-    if (
-      options.lazyUnloadCallback &&
-      options.lazyUnloadConditions?.includes('unselected')
-    ) {
-      unloadEvents.forEach((evt) => emblaApi.on(evt, lazyUnloadPreviousHandler));
-    }
-    document.addEventListener('visibilitychange', visibilityHandler);
-  }
-
-  function destroy(): void {
-    if (options.lazyLoadCallback) {
-      loadEvents.forEach((evt) => emblaApi.off(evt, lazyLoadHandler));
-    }
-    if (options.lazyUnloadCallback) {
-      unloadEvents.forEach((evt) => emblaApi.off(evt, lazyUnloadPreviousHandler));
-    }
-    document.removeEventListener('visibilitychange', visibilityHandler);
-  }
-
-  function visibilityHandler(): void {
-    if (
-      document.visibilityState === 'hidden' &&
-      options.lazyUnloadConditions?.includes('hidden')
-    ) {
-      lazyUnloadAllHandler();
-    } else if (document.visibilityState === 'visible' && options.lazyLoadCallback) {
-      lazyLoadHandler();
-    }
-  }
-
-  function hasLazyloaded(index: number): boolean {
-    return lazyLoadedSlides.has(index);
-  }
-
-  function lazyLoadHandler(): void {
-    const lazyLoadCount = options.lazyLoadCount;
-    const currentIndex = emblaApi.selectedScrollSnap();
-    const slidesToLoad = new Set<number>();
-
-    // Lazily load 'count' slides on either side of the slides in view.
-    for (let i = 1; i <= lazyLoadCount && currentIndex - i >= 0; i++) {
-      slidesToLoad.add(currentIndex - i);
-    }
-    slidesToLoad.add(currentIndex);
-    for (let i = 1; i <= lazyLoadCount && currentIndex + i < slides.length; i++) {
-      slidesToLoad.add(currentIndex + i);
-    }
-
-    slidesToLoad.forEach((index) => {
-      if (!hasLazyloaded(index) && options.lazyLoadCallback) {
-        lazyLoadedSlides.add(index);
-        options.lazyLoadCallback(index, slides[index]);
-      }
-    });
-  }
-
-  function lazyUnloadAllHandler(): void {
-    lazyLoadedSlides.forEach((index) => {
-      if (options.lazyUnloadCallback) {
-        options.lazyUnloadCallback(index, slides[index]);
-        lazyLoadedSlides.delete(index);
-      }
-    });
-  }
-
-  function lazyUnloadPreviousHandler(): void {
-    const index = emblaApi.previousScrollSnap();
-
-    if (hasLazyloaded(index) && options.lazyUnloadCallback) {
-      options.lazyUnloadCallback(index, slides[index]);
-      lazyLoadedSlides.delete(index);
-    }
-  }
-
-  const self: AutoLazyLoadType = {
-    name: 'autoLazyLoad',
-    options: userOptions,
-    init,
-    destroy,
-  };
-  return self;
-}