DEV: add support for custom post message callbacks

Allows for cleaner subscription to changes by plugins, polls will move to
it.

app/assets/javascripts/discourse/controllers/topic.js.es6

@@ -14,6 +14,16 @@ import { popupAjaxError } from 'discourse/lib/ajax-error';
 import { spinnerHTML } from 'discourse/helpers/loading-spinner';
 import { userPath } from 'discourse/lib/url';
 
+const customPostMessageCallbacks = {};
+
+export function registerCustomPostMessageCallback(type, callback) {
+  if (customPostMessageCallbacks[type]) {
+    throw `Error ${type} is an already registered post message!`;
+  }
+
+  customPostMessageCallbacks[type] = callback;
+}
+
 export default Ember.Controller.extend(BufferedContent, {
   composer: Ember.inject.controller(),
   application: Ember.inject.controller(),
@@ -935,9 +945,14 @@ export default Ember.Controller.extend(BufferedContent, {
           break;
         }
         default: {
+          let callback = customPostMessageCallbacks[data.type];
+          if (callback) {
+            callback(this, data);
+          } else {
             Em.Logger.warn("unknown topic bus message type", data);
           }
         }
+      }
 
       if (topic.get('isPrivateMessage') &&
           this.currentUser &&

app/assets/javascripts/discourse/lib/plugin-api.js.es6

@@ -25,9 +25,10 @@ import { modifySelectKit } from "select-kit/mixins/plugin-api";
 import { addGTMPageChangedCallback } from 'discourse/lib/page-tracker';
 import { registerCustomAvatarHelper } from 'discourse/helpers/user-avatar';
 import { disableNameSuppression } from 'discourse/widgets/poster-name';
+import { registerCustomPostMessageCallback as registerCustomPostMessageCallback1 } from 'discourse/controllers/topic';
 
 // If you add any methods to the API ensure you bump up this number
-const PLUGIN_API_VERSION = '0.8.21';
+const PLUGIN_API_VERSION = '0.8.22';
 
 class PluginApi {
   constructor(version, container) {
@@ -426,6 +427,24 @@ class PluginApi {
     disableNameSuppression();
   }
 
+  /**
+   * Registers a callback that will be invoked when the server calls
+   * Post#publish_change_to_clients! please ensure your type does not
+   * match acted,revised,rebaked,recovered, created,move_to_inbox or archived
+   *
+   * callback will be called with topicController and Message
+   *
+   * Example:
+   *
+   * api.registerCustomPostMessageCallback("applied_color", (topicController, message) => {
+   *   let stream = topicController.get("model.postStream");
+   *   // etc
+   * });
+   */
+  registerCustomPostMessageCallback(type, callback) {
+    registerCustomPostMessageCallback1(type, callback);
+  }
+
   /**
    * Changes a setting associated with a widget. For example, if
    * you wanted small avatars in the post stream: