FEATURE: allow plugins to transform, the transformed post

This allows plugins to amend posts prior to rendering.

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

@@ -17,9 +17,10 @@ import { addDiscoveryQueryParam } from 'discourse/controllers/discovery-sortable
 import { addTagsHtmlCallback } from 'discourse/lib/render-tags';
 import { addUserMenuGlyph } from 'discourse/widgets/user-menu';
 import { addPostClassesCallback } from 'discourse/widgets/post';
+import { addPostTransformCallback } from 'discourse/widgets/post-stream';
 
 // If you add any methods to the API ensure you bump up this number
-const PLUGIN_API_VERSION = '0.8.4';
+const PLUGIN_API_VERSION = '0.8.5';
 
 class PluginApi {
   constructor(version, container) {
@@ -438,6 +439,24 @@ class PluginApi {
   addPostClassesCallback(callback) {
     addPostClassesCallback(callback);
   }
+
+  /**
+   *
+   * Adds a callback to be executed on the "transformed" post that is passed to the post
+   * widget.
+   *
+   * This allows you to apply transformations on the actual post that is about to be rendered.
+   *
+   * Example:
+   *
+   * addPostTransformCallback((t)=>{
+   *  // post number 7 is overrated, don't show it ever
+   *  if (t.post_number === 7) { t.cooked = ""; }
+   * })
+   */
+  addPostTransformCallback(callback) {
+    addPostTransformCallback(callback);
+  }
 }
 
 let _pluginv01;

app/assets/javascripts/discourse/widgets/post-stream.js.es6

@@ -3,6 +3,21 @@ import transformPost from 'discourse/lib/transform-post';
 import { Placeholder } from 'discourse/lib/posts-with-placeholders';
 import { addWidgetCleanCallback } from 'discourse/components/mount-widget';
 
+let transformCallbacks = null;
+function postTransformCallbacks(transformed) {
+  if (transformCallbacks === null) {
+    return;
+  }
+
+  for(let i=0; i < transformCallbacks.length; i++) {
+    transformCallbacks[i].call(this, transformed);
+  }
+}
+export function addPostTransformCallback(callback){
+  transformCallbacks = transformCallbacks || [];
+  transformCallbacks.push(callback);
+};
+
 const CLOAKING_ENABLED = !window.inTestEnv;
 const DAY = 1000 * 60 * 60 * 24;
 
@@ -96,6 +111,8 @@ export default createWidget('post-stream', {
       transformed.height = _heights[post.id];
       transformed.cloaked = _cloaked[post.id];
 
+      postTransformCallbacks(transformed);
+
       if (transformed.isSmallAction) {
         result.push(this.attach('post-small-action', transformed, { model: post }));
       } else {