FEATURE: backend support for pushing notifications to clients

app/jobs/regular/push_notification.rb

@@ -0,0 +1,28 @@
+module Jobs
+  class PushNotification < Jobs::Base
+    def execute(args)
+      notification = args["payload"]
+      notification["url"] = UrlHelper.absolute(notification["post_url"])
+      notification.delete("post_url")
+
+      payload = {
+        secret_key: SiteSetting.push_api_secret_key,
+        url: Discourse.base_url,
+        title: SiteSetting.title,
+        description: SiteSetting.site_description,
+      }
+
+      clients = args["clients"]
+      clients.group_by{|r| r[1]}.each do |push_url, group|
+        notifications = group.map do |client_id, _|
+          notification.merge({
+            client_id: client_id
+          })
+        end
+
+        RestClient.send :post, push_url, payload.merge({notifications: notifications})
+      end
+
+    end
+  end
+end

app/services/post_alerter.rb

@@ -388,12 +388,26 @@ class PostAlerter
         }
 
         MessageBus.publish("/notification-alert/#{user.id}", payload, user_ids: [user.id])
+        push_notification(user, payload)
         DiscourseEvent.trigger(:post_notification_alert, user, payload)
      end
    end
 
   end
 
+  def push_notification(user, payload)
+    if SiteSetting.allow_push_user_api_keys && SiteSetting.allowed_user_api_push_urls.present?
+      clients = user.user_api_keys
+          .where('push AND push_url IS NOT NULL AND position(push_url in ?) > 0 AND revoked_at IS NULL',
+                  SiteSetting.allowed_user_api_push_urls)
+          .pluck(:client_id, :push_url)
+
+      if clients.length > 0
+        Jobs.enqueue(:push_notification, clients: clients, payload: payload, user_id: user.id)
+      end
+    end
+  end
+
   def expand_group_mentions(groups, post)
     return unless post.user && groups
 

config/initializers/005-site_settings.rb

@@ -7,6 +7,11 @@ reload_settings = lambda {
   RailsMultisite::ConnectionManagement.each_connection do
     begin
       SiteSetting.refresh!
+
+      unless String === SiteSetting.push_api_secret_key && SiteSetting.push_api_secret_key.length == 32
+        SiteSetting.push_api_secret_key = SecureRandom.hex
+      end
+
     rescue ActiveRecord::StatementInvalid
       # This will happen when migrating a new database
     rescue => e

config/site_settings.yml

@@ -1270,11 +1270,14 @@ user_api:
     default: true
   max_api_keys_per_user:
     default: 10
+  push_api_secret_key:
+    hidden: true
   min_trust_level_for_user_api_key:
     default: 1
   allowed_user_api_push_urls:
     default: ''
     type: list
+    shadowed_by_global: true
   allowed_user_api_auth_redirects:
     default: 'https://api.discourse.org/api/auth_redirect|discourse://auth_redirect'
     type: list

spec/services/post_alerter_spec.rb

@@ -326,6 +326,64 @@ describe PostAlerter do
     end
   end
 
+  describe "push_notification" do
+    let(:mention_post) { create_post_with_alerts(user: user, raw: 'Hello @eviltrout')}
+    let(:topic) { mention_post.topic }
+
+    it "correctly pushes notifications if configured correctly" do
+      SiteSetting.allowed_user_api_push_urls = "https://site.com/push|https://site2.com/push"
+
+      2.times do |i|
+        UserApiKey.create!(user_id: evil_trout.id,
+                           client_id: "xxx#{i}",
+                           key: "yyy#{i}",
+                           application_name: "iPhone#{i}",
+                           read: true,
+                           write: true,
+                           push: true,
+                           push_url: "https://site2.com/push")
+      end
+
+      # I want to test payload ... but we have chicked egg problem
+      # if I test it then it makes the req and the the expects is not correct ...
+      # need to track all reqs in rest client and check after the fact
+
+      # payload = {
+      #   secret_key: SiteSetting.push_api_secret_key,
+      #   url: Discourse.base_url,
+      #   title: SiteSetting.title,
+      #   description: SiteSetting.site_description,
+      #   notifications: [
+      #   {
+      #     'notification_type' => 1,
+      #     'post_number' => 1,
+      #     'topic_title' => topic.title,
+      #     'topic_id' => topic.id,
+      #     'excerpt' => 'Hello @eviltrout',
+      #     'username' => user.username,
+      #     'url' => UrlHelper.absolute(mention_post.url),
+      #     'client_id' => 'xxx0'
+      #   },
+      #   {
+      #     'notification_type' => 1,
+      #     'post_number' => 1,
+      #     'topic_title' => topic.title,
+      #     'topic_id' => topic.id,
+      #     'excerpt' => 'Hello @eviltrout',
+      #     'username' => user.username,
+      #     'url' => UrlHelper.absolute(mention_post.url),
+      #     'client_id' => 'xxx1'
+      #   }
+      #   ]
+      # }
+
+      # should only happen once even though we are using 2 keys
+      RestClient.expects(:post).returns("OK")
+
+      mention_post
+    end
+  end
+
   describe "watching_first_post" do
     let(:group) { Fabricate(:group) }
     let(:user) { Fabricate(:user) }