Adds the ability to push new posts onto discussions that aren't public. (#17)

It's very frustrating having pusher installed, but not seeing new posts pop up on non public
discussions. This PR simply re-uses the existing channels per user by reading
all similar private user channels (which require authentication) and then pushing
the websocket message over the line. This only happens in case the discussion is
not public and it only sends to connected users.

extensions/pusher/js/src/forum/index.js

@@ -9,7 +9,7 @@ import Button from 'flarum/components/Button';
 
 app.initializers.add('flarum-pusher', () => {
   const loadPusher = new Promise((resolve) => {
-    $.getScript('//cdn.jsdelivr.net/npm/pusher-js@3.0.0/dist/pusher.min.js', () => {
+    $.getScript('//cdn.jsdelivr.net/npm/pusher-js@7.0.3/dist/web/pusher.min.js', () => {
       const socket = new Pusher(app.forum.attribute('pusherKey'), {
         authEndpoint: app.forum.attribute('apiUrl') + '/pusher/auth',
         cluster: app.forum.attribute('pusherCluster'),
@@ -21,8 +21,11 @@ app.initializers.add('flarum-pusher', () => {
       });
 
       return resolve({
-        main: socket.subscribe('public'),
-        user: app.session.user ? socket.subscribe('private-user' + app.session.user.id()) : null
+        channels: {
+          main: socket.subscribe('public'),
+          user: app.session.user ? socket.subscribe('private-user' + app.session.user.id()) : null
+        },
+        pusher: socket
       });
     });
   });
@@ -31,8 +34,10 @@ app.initializers.add('flarum-pusher', () => {
   app.pushedUpdates = [];
 
   extend(DiscussionList.prototype, 'oncreate', function() {
-    app.pusher.then(channels => {
-      channels.main.bind('newPost', data => {
+    app.pusher.then(binding => {
+      const pusher = binding.pusher;
+
+      pusher.bind('newPost', data => {
         const params = app.discussions.getParams();
 
         if (!params.q && !params.sort && !params.filter) {
@@ -59,8 +64,8 @@ app.initializers.add('flarum-pusher', () => {
   });
 
   extend(DiscussionList.prototype, 'onremove', function () {
-    app.pusher.then(channels => {
-      channels.main.unbind('newPost');
+    app.pusher.then(binding => {
+      binding.pusher.unbind('newPost');
     });
   });
 
@@ -107,8 +112,10 @@ app.initializers.add('flarum-pusher', () => {
   });
 
   extend(DiscussionPage.prototype, 'oncreate', function() {
-    app.pusher.then(channels => {
-      channels.main.bind('newPost', data => {
+    app.pusher.then(binding => {
+      const pusher = binding.pusher;
+
+      pusher.bind('newPost', data => {
         const id = String(data.discussionId);
 
         if (this.discussion && this.discussion.id() === id && this.stream) {
@@ -129,8 +136,8 @@ app.initializers.add('flarum-pusher', () => {
   });
 
   extend(DiscussionPage.prototype, 'onremove', function () {
-    app.pusher.then(channels => {
-      channels.main.unbind('newPost')
+    app.pusher.then(binding => {
+      binding.pusher.unbind('newPost');
     });
   });
 
@@ -138,7 +145,9 @@ app.initializers.add('flarum-pusher', () => {
     items.remove('refresh');
   });
 
-  app.pusher.then(channels => {
+  app.pusher.then(binding => {
+    const channels = binding.channels;
+
     if (channels.user) {
       channels.user.bind('notification', () => {
         app.session.user.pushAttributes({

extensions/pusher/src/Listener/PushNewPost.php

@@ -11,6 +11,8 @@ namespace Flarum\Pusher\Listener;
 
 use Flarum\Post\Event\Posted;
 use Flarum\User\Guest;
+use Flarum\User\User;
+use Illuminate\Support\Str;
 use Pusher;
 
 class PushNewPost
@@ -27,10 +29,33 @@ class PushNewPost
 
     public function handle(Posted $event)
     {
+        $channels = [];
+
         if ($event->post->isVisibleTo(new Guest)) {
+            $channels[] = 'public';
+        } else {
+            // Retrieve private channels, used for each user.
+            $response = $this->pusher->get_channels([
+                'filter_by_prefix' => 'private-user'
+            ]);
+
+            if (! $response) {
+                return;
+            }
+
+            foreach ($response->channels as $name => $channel) {
+                $userId = Str::after($name, 'private-user');
+
+                if (($user = User::find($userId)) && $event->post->isVisibleTo($user)) {
+                    $channels[] = $name;
+                }
+            }
+        }
+
+        if (count($channels)) {
             $tags = $event->post->discussion->tags;
 
-            $this->pusher->trigger('public', 'newPost', [
+            $this->pusher->trigger($channels, 'newPost', [
                 'postId' => $event->post->id,
                 'discussionId' => $event->post->discussion->id,
                 'tagIds' => $tags ? $tags->pluck('id') : null