From bbc32278d8c6ee6744c36e00934a3a6fd351f7a9 Mon Sep 17 00:00:00 2001
From: Paulus Schoutsen <paulus@home-assistant.io>
Date: Tue, 12 Mar 2019 19:43:04 -0700
Subject: [PATCH] Cache thumbnails (#2924)

---
 src/cards/ha-media_player-card.js             | 12 +++--
 .../util/time-cache-function-promise.ts       | 47 +++++++++++++++++++
 src/data/camera.ts                            |  6 +++
 src/data/media-player.ts                      | 31 ++++++++++++
 src/panels/lovelace/components/hui-image.ts   | 10 ++--
 5 files changed, 97 insertions(+), 9 deletions(-)
 create mode 100644 src/common/util/time-cache-function-promise.ts

diff --git a/src/cards/ha-media_player-card.js b/src/cards/ha-media_player-card.js
index 6bbda8eab6..cb068c3afe 100644
--- a/src/cards/ha-media_player-card.js
+++ b/src/cards/ha-media_player-card.js
@@ -6,6 +6,7 @@ import { html } from "@polymer/polymer/lib/utils/html-tag";
 import { PolymerElement } from "@polymer/polymer/polymer-element";
 
 import HassMediaPlayerEntity from "../util/hass-media-player-model";
+import { fetchMediaPlayerThumbnailWithCache } from "../data/media-player";
 
 import computeStateName from "../common/entity/compute_state_name";
 import EventsMixin from "../mixins/events-mixin";
@@ -271,10 +272,13 @@ class HaMediaPlayerCard extends LocalizeMixin(EventsMixin(PolymerElement)) {
 
     // We have a new picture url
     try {
-      const { content_type: contentType, content } = await this.hass.callWS({
-        type: "media_player_thumbnail",
-        entity_id: playerObj.stateObj.entity_id,
-      });
+      const {
+        content_type: contentType,
+        content,
+      } = await fetchMediaPlayerThumbnailWithCache(
+        this.hass,
+        playerObj.stateObj.entity_id
+      );
       this._coverShowing = true;
       this._coverLoadError = false;
       this.$.cover.style.backgroundImage = `url(data:${contentType};base64,${content})`;
diff --git a/src/common/util/time-cache-function-promise.ts b/src/common/util/time-cache-function-promise.ts
new file mode 100644
index 0000000000..8dc8abcd3f
--- /dev/null
+++ b/src/common/util/time-cache-function-promise.ts
@@ -0,0 +1,47 @@
+import { HomeAssistant } from "../../types";
+
+interface ResultCache<T> {
+  [entityId: string]: Promise<T> | undefined;
+}
+
+export const timeCachePromiseFunc = async <T>(
+  cacheKey: string,
+  cacheTime: number,
+  func: (
+    hass: HomeAssistant,
+    entityId: string,
+    ...args: Array<unknown>
+  ) => Promise<T>,
+  hass: HomeAssistant,
+  entityId: string,
+  ...args: Array<unknown>
+): Promise<T> => {
+  let cache: ResultCache<T> | undefined = (hass as any)[cacheKey];
+
+  if (!cache) {
+    cache = hass[cacheKey] = {};
+  }
+
+  const lastResult = cache[entityId];
+
+  if (lastResult) {
+    return lastResult;
+  }
+
+  const result = func(hass, entityId, ...args);
+  cache[entityId] = result;
+
+  result.then(
+    // When successful, set timer to clear cache
+    () =>
+      setTimeout(() => {
+        cache![entityId] = undefined;
+      }, cacheTime),
+    // On failure, clear cache right away
+    () => {
+      cache![entityId] = undefined;
+    }
+  );
+
+  return result;
+};
diff --git a/src/data/camera.ts b/src/data/camera.ts
index 64eec22d15..62f94096e4 100644
--- a/src/data/camera.ts
+++ b/src/data/camera.ts
@@ -1,4 +1,5 @@
 import { HomeAssistant, CameraEntity } from "../types";
+import { timeCachePromiseFunc } from "../common/util/time-cache-function-promise";
 
 export interface CameraThumbnail {
   content_type: string;
@@ -14,6 +15,11 @@ export const computeMJPEGStreamUrl = (entity: CameraEntity) =>
     entity.attributes.access_token
   }`;
 
+export const fetchThumbnailWithCache = (
+  hass: HomeAssistant,
+  entityId: string
+) => timeCachePromiseFunc("_cameraTmb", 9000, fetchThumbnail, hass, entityId);
+
 export const fetchThumbnail = (hass: HomeAssistant, entityId: string) =>
   hass.callWS<CameraThumbnail>({
     type: "camera_thumbnail",
diff --git a/src/data/media-player.ts b/src/data/media-player.ts
index 7d89d4d544..3aaf16e093 100644
--- a/src/data/media-player.ts
+++ b/src/data/media-player.ts
@@ -1,4 +1,35 @@
+import { HomeAssistant } from "../types";
+
+import { timeCachePromiseFunc } from "../common/util/time-cache-function-promise";
+
 export const SUPPORT_PAUSE = 1;
 export const SUPPORT_NEXT_TRACK = 32;
 export const SUPPORTS_PLAY = 16384;
 export const OFF_STATES = ["off", "idle"];
+
+export interface MediaPlayerThumbnail {
+  content_type: string;
+  content: string;
+}
+
+export const fetchMediaPlayerThumbnailWithCache = (
+  hass: HomeAssistant,
+  entityId: string
+) =>
+  timeCachePromiseFunc(
+    "_media_playerTmb",
+    9000,
+    fetchMediaPlayerThumbnail,
+    hass,
+    entityId
+  );
+
+export const fetchMediaPlayerThumbnail = (
+  hass: HomeAssistant,
+  entityId: string
+) => {
+  return hass.callWS<MediaPlayerThumbnail>({
+    type: "media_player_thumbnail",
+    entity_id: entityId,
+  });
+};
diff --git a/src/panels/lovelace/components/hui-image.ts b/src/panels/lovelace/components/hui-image.ts
index 213220772d..7f9bd87e95 100644
--- a/src/panels/lovelace/components/hui-image.ts
+++ b/src/panels/lovelace/components/hui-image.ts
@@ -18,7 +18,7 @@ import { HomeAssistant } from "../../../types";
 import { styleMap } from "lit-html/directives/style-map";
 import { classMap } from "lit-html/directives/class-map";
 import { b64toBlob } from "../../../common/file/b64-to-blob";
-import { fetchThumbnail } from "../../../data/camera";
+import { fetchThumbnailWithCache } from "../../../data/camera";
 
 const UPDATE_INTERVAL = 10000;
 const DEFAULT_FILTER = "grayscale(100%)";
@@ -179,10 +179,10 @@ class HuiImage extends LitElement {
       return;
     }
     try {
-      const { content_type: contentType, content } = await fetchThumbnail(
-        this.hass,
-        this.cameraImage
-      );
+      const {
+        content_type: contentType,
+        content,
+      } = await fetchThumbnailWithCache(this.hass, this.cameraImage);
       if (this._cameraImageSrc) {
         URL.revokeObjectURL(this._cameraImageSrc);
       }