Refactor dashboard conditional listeners to use mixin (#27837)

* Update media query to new APIs

* Refactor conditional rendering

* Cleanup

* Restore original functionality

* Restore

* Reduce

* Reduce

* Reduce

* Restore legacy code while we still support them

* Clear conditional listeners before setting up again

src/mixins/conditional-listener-mixin.ts

@@ -0,0 +1,104 @@
+import type { ReactiveElement } from "lit";
+import { listenMediaQuery } from "../common/dom/media_query";
+import type { HomeAssistant } from "../types";
+import type { Condition } from "../panels/lovelace/common/validate-condition";
+import { checkConditionsMet } from "../panels/lovelace/common/validate-condition";
+
+type Constructor<T> = abstract new (...args: any[]) => T;
+
+/**
+ * Extract media queries from conditions recursively
+ */
+export function extractMediaQueries(conditions: Condition[]): string[] {
+  return conditions.reduce<string[]>((array, c) => {
+    if ("conditions" in c && c.conditions) {
+      array.push(...extractMediaQueries(c.conditions));
+    }
+    if (c.condition === "screen" && c.media_query) {
+      array.push(c.media_query);
+    }
+    return array;
+  }, []);
+}
+
+/**
+ * Helper to setup media query listeners for conditional visibility
+ */
+export function setupMediaQueryListeners(
+  conditions: Condition[],
+  hass: HomeAssistant,
+  addListener: (unsub: () => void) => void,
+  onUpdate: (conditionsMet: boolean) => void
+): void {
+  const mediaQueries = extractMediaQueries(conditions);
+
+  if (mediaQueries.length === 0) return;
+
+  // Optimization for single media query
+  const hasOnlyMediaQuery =
+    conditions.length === 1 &&
+    conditions[0].condition === "screen" &&
+    !!conditions[0].media_query;
+
+  mediaQueries.forEach((mediaQuery) => {
+    const unsub = listenMediaQuery(mediaQuery, (matches) => {
+      if (hasOnlyMediaQuery) {
+        onUpdate(matches);
+      } else {
+        const conditionsMet = checkConditionsMet(conditions, hass);
+        onUpdate(conditionsMet);
+      }
+    });
+    addListener(unsub);
+  });
+}
+
+/**
+ * Mixin to handle conditional listeners for visibility control
+ *
+ * Provides lifecycle management for listeners (media queries, time-based, state changes, etc.)
+ * that control conditional visibility of components.
+ *
+ * Usage:
+ * 1. Extend your component with ConditionalListenerMixin(ReactiveElement)
+ * 2. Override setupConditionalListeners() to setup your listeners
+ * 3. Use addConditionalListener() to register unsubscribe functions
+ * 4. Call clearConditionalListeners() and setupConditionalListeners() when config changes
+ *
+ * The mixin automatically:
+ * - Sets up listeners when component connects to DOM
+ * - Cleans up listeners when component disconnects from DOM
+ */
+export const ConditionalListenerMixin = <
+  T extends Constructor<ReactiveElement>,
+>(
+  superClass: T
+) => {
+  abstract class ConditionalListenerClass extends superClass {
+    private __listeners: (() => void)[] = [];
+
+    public connectedCallback() {
+      super.connectedCallback();
+      this.setupConditionalListeners();
+    }
+
+    public disconnectedCallback() {
+      super.disconnectedCallback();
+      this.clearConditionalListeners();
+    }
+
+    protected clearConditionalListeners(): void {
+      this.__listeners.forEach((unsub) => unsub());
+      this.__listeners = [];
+    }
+
+    protected addConditionalListener(unsubscribe: () => void): void {
+      this.__listeners.push(unsubscribe);
+    }
+
+    protected setupConditionalListeners(): void {
+      // Override in subclass
+    }
+  }
+  return ConditionalListenerClass;
+};