Add android fallback for background push notifications (#102)

src/app/util/push/adapters/web.ts

@@ -0,0 +1,73 @@
+import {pubkey} from "@welshman/app"
+import {maybe} from "@welshman/lib"
+import type {Unsubscriber} from "svelte/store"
+import {getPubkeyTagValues, matchFilter, type TrustedEvent} from "@welshman/util"
+import {DM_KINDS, notificationSettings} from "@app/core/state"
+import type {IPushAdapter} from "@app/util/push/adapters/common"
+import {onNotification} from "@app/util/push/adapters/common"
+import {goToEvent} from "@app/util/routes"
+
+export class WebNotifications implements IPushAdapter {
+  _unsubscriber = maybe<Unsubscriber>()
+
+  async request(prompt = true) {
+    if (prompt && Notification?.permission === "default") {
+      await Notification.requestPermission()
+    }
+
+    return Notification?.permission || "denied"
+  }
+
+  _notify(event: TrustedEvent, title: string, body: string) {
+    console.log("notify:", event)
+
+    const notification = new Notification(title, {
+      body,
+      tag: event.id,
+      icon: "/icon.png",
+      badge: "/icon.png",
+    })
+
+    notification.onclick = () => {
+      window.focus()
+      goToEvent(event)
+      notification.close()
+    }
+
+    const onVisibilityChange = () => {
+      if (document.visibilityState === "visible") {
+        notification.close()
+        document.removeEventListener("visibilitychange", onVisibilityChange)
+      }
+    }
+
+    document.addEventListener("visibilitychange", onVisibilityChange)
+  }
+
+  async enable() {
+    if (!this._unsubscriber) {
+      this._unsubscriber = onNotification(event => {
+        const {push, messages, mentions, spaces} = notificationSettings.get()
+
+        if (push && document.hidden && Notification?.permission === "granted") {
+          if (messages && matchFilter({kinds: DM_KINDS}, event)) {
+            this._notify(event, "New direct message", "Someone sent you a direct message.")
+          } else if (
+            mentions &&
+            event.pubkey !== pubkey.get() &&
+            getPubkeyTagValues(event.tags).includes(pubkey.get()!)
+          ) {
+            this._notify(event, "Someone mentioned you", "Someone tagged you in a message.")
+          } else if (spaces) {
+            this._notify(event, "New activity", "Someone posted a new message.")
+          }
+        }
+      })
+    }
+  }
+
+  async disable() {
+    this._unsubscriber?.()
+    this._unsubscriber = undefined
+  }
+}