Rename things, add comments

web/src/app/WebPushWorker.js

@@ -1,84 +0,0 @@
-import { useState, useEffect } from "react";
-import { useLiveQuery } from "dexie-react-hooks";
-import notifier from "./Notifier";
-import subscriptionManager from "./SubscriptionManager";
-
-export const useWebPushUpdateWorker = () => {
-  const topics = useLiveQuery(() => subscriptionManager.webPushTopics());
-  const [lastTopics, setLastTopics] = useState();
-
-  useEffect(() => {
-    if (!notifier.pushPossible() || JSON.stringify(topics) === JSON.stringify(lastTopics)) {
-      return;
-    }
-
-    (async () => {
-      try {
-        console.log("[useWebPushUpdateWorker] Refreshing web push subscriptions");
-
-        await subscriptionManager.refreshWebPushSubscriptions(topics);
-
-        setLastTopics(topics);
-      } catch (e) {
-        console.error("[useWebPushUpdateWorker] Error refreshing web push subscriptions", e);
-      }
-    })();
-  }, [topics, lastTopics]);
-};
-
-const intervalMillis = 13 * 60 * 1_000; // 13 minutes
-const updateIntervalMillis = 60 * 60 * 1_000; // 1 hour
-
-class WebPushRefreshWorker {
-  constructor() {
-    this.timer = null;
-    this.lastUpdate = null;
-    this.messageHandler = this.onMessage.bind(this);
-    this.visibilityHandler = this.onVisibilityChange.bind(this);
-  }
-
-  startWorker() {
-    if (this.timer !== null) {
-      return;
-    }
-
-    this.timer = setInterval(() => this.updateSubscriptions(), intervalMillis);
-
-    this.broadcastChannel = new BroadcastChannel("web-push-broadcast");
-    this.broadcastChannel.addEventListener("message", this.messageHandler);
-
-    document.addEventListener("visibilitychange", this.visibilityHandler);
-  }
-
-  stopWorker() {
-    clearTimeout(this.timer);
-
-    this.broadcastChannel.removeEventListener("message", this.messageHandler);
-    this.broadcastChannel.close();
-
-    document.removeEventListener("visibilitychange", this.visibilityHandler);
-  }
-
-  onMessage() {
-    notifier.playSound();
-  }
-
-  onVisibilityChange() {
-    if (document.visibilityState === "visible") {
-      this.updateSubscriptions();
-    }
-  }
-
-  async updateSubscriptions() {
-    if (!notifier.pushPossible()) {
-      return;
-    }
-
-    if (!this.lastUpdate || Date.now() - this.lastUpdate > updateIntervalMillis) {
-      await subscriptionManager.refreshWebPushSubscriptions();
-      this.lastUpdate = Date.now();
-    }
-  }
-}
-
-export const webPushRefreshWorker = new WebPushRefreshWorker();