Template markdown card (#3451)

* Render templates in markdown card

* Add manual entity_id option

* Linting

* Address review comments

* Address review comments

* Address review comments

* Address review comments

* Tweak disconnect function

* Remove cardSize instance variable

* Fix demo

src/data/ws-templates.ts

@@ -0,0 +1,20 @@
+import { Connection, UnsubscribeFunc } from "home-assistant-js-websocket";
+
+interface RenderTemplateResult {
+  result: string;
+}
+
+export const subscribeRenderTemplate = (
+  conn: Connection,
+  onChange: (result: string) => void,
+  params: {
+    template: string;
+    entity_ids?: string | string[];
+    variables?: object;
+  }
+): Promise<UnsubscribeFunc> => {
+  return conn.subscribeMessage(
+    (msg: RenderTemplateResult) => onChange(msg.result),
+    { type: "render_template", ...params }
+  );
+};

src/fake_data/provide_hass.ts

@@ -24,7 +24,10 @@ export interface MockHomeAssistant extends HomeAssistant {
   updateHass(obj: Partial<MockHomeAssistant>);
   updateStates(newStates: HassEntities);
   addEntities(entites: Entity | Entity[], replace?: boolean);
-  mockWS(type: string, callback: (msg: any) => any);
+  mockWS(
+    type: string,
+    callback: (msg: any, onChange?: (response: any) => void) => any
+  );
   mockAPI(path: string | RegExp, callback: MockRestCallback);
   mockEvent(event);
   mockTheme(theme: { [key: string]: string } | null);
@@ -108,7 +111,7 @@ export const provideHass = (
           console.error(`Unknown WS command: ${msg.type}`);
         }
       },
-      sendMessagePromise: (msg) => {
+      sendMessagePromise: async (msg) => {
         const callback = wsCommands[msg.type];
         return callback
           ? callback(msg)
@@ -119,6 +122,17 @@ export const provideHass = (
               } is not implemented in provide_hass.`,
             });
       },
+      subscribeMessage: async (onChange, msg) => {
+        const callback = wsCommands[msg.type];
+        return callback
+          ? callback(msg, onChange)
+          : Promise.reject({
+              code: "command_not_mocked",
+              message: `WS Command ${
+                msg.type
+              } is not implemented in provide_hass.`,
+            });
+      },
       subscribeEvents: async (
         // @ts-ignore
         callback,

src/panels/lovelace/cards/hui-markdown-card.ts

@@ -8,12 +8,15 @@ import {
   CSSResult,
 } from "lit-element";
 import { classMap } from "lit-html/directives/class-map";
+import { UnsubscribeFunc } from "home-assistant-js-websocket";
 
 import "../../../components/ha-card";
 import "../../../components/ha-markdown";
 
+import { HomeAssistant } from "../../../types";
 import { LovelaceCard, LovelaceCardEditor } from "../types";
 import { MarkdownCardConfig } from "./types";
+import { subscribeRenderTemplate } from "../../../data/ws-templates";
 
 @customElement("hui-markdown-card")
 export class HuiMarkdownCard extends LitElement implements LovelaceCard {
@@ -27,11 +30,16 @@ export class HuiMarkdownCard extends LitElement implements LovelaceCard {
   }
 
   @property() private _config?: MarkdownCardConfig;
+  @property() private _content?: string = "";
+  @property() private _unsubRenderTemplate?: Promise<UnsubscribeFunc>;
+  @property() private _hass?: HomeAssistant;
 
   public getCardSize(): number {
-    return (
+    return this._config === undefined
-      this._config!.content.split("\n").length + (this._config!.title ? 1 : 0)
+      ? 3
-    );
+      : this._config.card_size === undefined
+      ? this._config.content.split("\n").length + (this._config.title ? 1 : 0)
+      : this._config.card_size;
   }
 
   public setConfig(config: MarkdownCardConfig): void {
@@ -40,6 +48,20 @@ export class HuiMarkdownCard extends LitElement implements LovelaceCard {
     }
 
     this._config = config;
+
+    this._disconnect();
+    if (this._hass) {
+      this._connect();
+    }
+  }
+
+  public disconnectedCallback() {
+    this._disconnect();
+  }
+
+  public set hass(hass) {
+    this._hass = hass;
+    this._connect();
   }
 
   protected render(): TemplateResult | void {
@@ -53,12 +75,47 @@ export class HuiMarkdownCard extends LitElement implements LovelaceCard {
           class="markdown ${classMap({
             "no-header": !this._config.title,
           })}"
-          .content="${this._config.content}"
+          .content="${this._content}"
         ></ha-markdown>
       </ha-card>
     `;
   }
 
+  private async _connect() {
+    if (!this._unsubRenderTemplate && this._hass && this._config) {
+      this._unsubRenderTemplate = subscribeRenderTemplate(
+        this._hass.connection,
+        (result) => {
+          this._content = result;
+        },
+        {
+          template: this._config.content,
+          entity_ids: this._config.entity_id,
+        }
+      );
+      this._unsubRenderTemplate.catch(() => {
+        this._content = this._config!.content;
+        this._unsubRenderTemplate = undefined;
+      });
+    }
+  }
+
+  private async _disconnect() {
+    if (this._unsubRenderTemplate) {
+      try {
+        const unsub = await this._unsubRenderTemplate;
+        this._unsubRenderTemplate = undefined;
+        await unsub();
+      } catch (e) {
+        if (e.code === "not_found") {
+          // If we get here, the connection was probably already closed. Ignore.
+        } else {
+          throw e;
+        }
+      }
+    }
+  }
+
   static get styles(): CSSResult {
     return css`
       ha-markdown {

src/panels/lovelace/cards/types.ts

@@ -118,6 +118,8 @@ export interface MarkdownCardConfig extends LovelaceCardConfig {
   type: "markdown";
   content: string;
   title?: string;
+  card_size?: number;
+  entity_ids?: string | string[];
 }
 
 export interface MediaControlCardConfig extends LovelaceCardConfig {