Add android fallback for background push notifications (#102)

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

@@ -0,0 +1,208 @@
+import {goto} from "$app/navigation"
+import type {Subscriber, Unsubscriber} from "svelte/store"
+import {
+  PushNotifications,
+  type ActionPerformed,
+  type RegistrationError,
+  type Token,
+} from "@capacitor/push-notifications"
+import type {PluginListenerHandle} from "@capacitor/core"
+import {pubkey, repository, tracker, userMessagingRelayList} from "@welshman/app"
+import {merged} from "@welshman/store"
+import {assoc, call, now, on, poll, spec, throttle} from "@welshman/lib"
+import {load, LOCAL_RELAY_URL} from "@welshman/net"
+import type {RepositoryUpdate} from "@welshman/net"
+import {
+  getIdFilters,
+  getRelaysFromList,
+  getTagValue,
+  matchFilters,
+  type Filter,
+  type TrustedEvent,
+} from "@welshman/util"
+import {
+  DM_KINDS,
+  CONTENT_KINDS,
+  MESSAGE_KINDS,
+  notificationSettings,
+  pushState,
+  shouldNotify,
+  userSpaceUrls,
+  userSettingsValues,
+  makeCommentFilter,
+} from "@app/core/state"
+import {makeSpacePath, getEventPath} from "@app/util/routes"
+
+export interface IPushAdapter {
+  request: (prompt?: boolean) => Promise<string>
+  disable: () => Promise<void>
+  enable: () => Promise<void>
+}
+
+export type PushPermissionResult = {
+  token?: string
+  error?: string
+}
+
+export const onNotification = call(() => {
+  const allFilters = [{kinds: [...MESSAGE_KINDS, ...DM_KINDS]}, makeCommentFilter(MESSAGE_KINDS)]
+  const filters = allFilters.map(assoc("since", now()))
+  const subscribers: Subscriber<TrustedEvent>[] = []
+
+  let unsubscribe: Unsubscriber | undefined
+
+  return (f: (event: TrustedEvent) => void) => {
+    subscribers.push(f)
+
+    if (!unsubscribe) {
+      unsubscribe = on(repository, "update", ({added}: RepositoryUpdate) => {
+        const $pubkey = pubkey.get()
+
+        for (const event of added) {
+          if (event.pubkey == $pubkey) {
+            continue
+          }
+
+          const h = getTagValue("h", event.tags)
+
+          if (Array.from(tracker.getRelays(event.id)).every(url => !shouldNotify(url, h))) {
+            continue
+          }
+
+          if (matchFilters(filters, event)) {
+            for (const f of subscribers) {
+              f(event)
+            }
+          }
+        }
+      })
+    }
+
+    return () => {
+      subscribers.splice(subscribers.indexOf(f), 1)
+
+      if (subscribers.length === 0) {
+        unsubscribe?.()
+        unsubscribe = undefined
+      }
+    }
+  }
+})
+
+export const onPushNotificationAction = async (action: ActionPerformed) => {
+  const {relay, id} = action.notification.data
+
+  const [event] = await load({
+    relays: [relay, LOCAL_RELAY_URL],
+    filters: getIdFilters([id]),
+  })
+
+  if (event) {
+    goto(await getEventPath(event, [relay]))
+  } else {
+    goto(makeSpacePath(relay))
+  }
+}
+
+export const requestPermissions = async (): Promise<string> => {
+  let status = await PushNotifications.checkPermissions()
+
+  if (["prompt", "prompt-with-rationale"].includes(status.receive)) {
+    status = await PushNotifications.requestPermissions()
+  }
+
+  return status.receive
+}
+
+export const requestToken = async (): Promise<PushPermissionResult> => {
+  let {token} = pushState.get()
+  let error = "failed to retrieve token"
+
+  if (!token) {
+    const listeners = [
+      PushNotifications.addListener("registration", ({value}: Token) => {
+        token = value
+      }),
+      PushNotifications.addListener("registrationError", (err: RegistrationError) => {
+        error = err.error
+      }),
+    ]
+
+    await Promise.all([
+      PushNotifications.register(),
+      poll({
+        condition: () => Boolean(token),
+        signal: AbortSignal.timeout(5000),
+      }),
+    ])
+
+    listeners.forEach(p => p.then((listener: PluginListenerHandle) => listener.remove()))
+  }
+
+  return token ? {token} : {error}
+}
+
+export const syncRelaySubscriptions = (
+  signal: AbortSignal,
+  sync: (url: string, key: string, filters: Filter[], ignore: Filter[]) => void,
+) => {
+  const $pubkey = pubkey.get()
+
+  if (!$pubkey) {
+    throw new Error("Attempted to sync push subscriptions without an active pubkey")
+  }
+
+  const unsubscribeSpaces = merged([
+    userSpaceUrls,
+    notificationSettings,
+    userSettingsValues,
+  ]).subscribe(
+    throttle(3000, ([$userSpaceUrls, {spaces, mentions}, {alerts}]) => {
+      const baseFilters = [{kinds: MESSAGE_KINDS}, makeCommentFilter(CONTENT_KINDS)]
+
+      for (const url of $userSpaceUrls) {
+        const {notify = true, exceptions = []} = alerts.find(spec({url})) || {}
+        const filters: Filter[] = []
+        const ignore: Filter[] = []
+
+        if (spaces) {
+          if (notify) {
+            if (exceptions.length > 0) {
+              ignore.push({"#h": exceptions})
+            }
+            filters.push(...baseFilters)
+          } else {
+            if (exceptions.length > 0) {
+              filters.push(...baseFilters.map(f => ({...f, "#h": exceptions})))
+            }
+          }
+        }
+
+        if (mentions) {
+          filters.push(...baseFilters.map(f => ({...f, "#p": [$pubkey]})))
+        }
+
+        sync(url, "spaces", filters, ignore)
+      }
+    }),
+  )
+
+  const unsubscribeMessages = merged([userMessagingRelayList, notificationSettings]).subscribe(
+    throttle(3000, ([$userMessagingRelayList, {messages}]) => {
+      for (const url of getRelaysFromList($userMessagingRelayList)) {
+        const filters: Filter[] = []
+
+        if (messages) {
+          filters.push({kinds: DM_KINDS, "#p": [$pubkey]})
+        }
+
+        sync(url, "messages", filters, [])
+      }
+    }),
+  )
+
+  signal.addEventListener("abort", () => {
+    unsubscribeSpaces()
+    unsubscribeMessages()
+  })
+}