Fix assignment of post number to progress position

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

@@ -629,10 +629,9 @@ export default ObjectController.extend(Discourse.SelectedPostsCount, {
     if (!post) { return; }
 
     var postStream = this.get('postStream'),
-        lastLoadedPost = postStream.get('lastLoadedPost'),
-        index = postStream.get('stream').indexOf(post.get('id'))+1;
+        lastLoadedPost = postStream.get('lastLoadedPost');
 
-    this.set('controllers.topic-progress.progressPosition', index);
+    this.set('controllers.topic-progress.progressPosition', postStream.progressIndexOfPost(post));
 
     if (lastLoadedPost && lastLoadedPost === post) {
       postStream.appendMore();

app/assets/javascripts/discourse/lib/url.js

@@ -220,7 +220,9 @@ Discourse.URL = Em.Object.createWithMixins({
             highlightOnInsert: closest,
             enteredAt: new Date().getTime().toString()
           });
-          topicProgressController.set('progressPosition', closest);
+          var closestPost = postStream.closestPostForPostNumber(closest),
+              progress = postStream.progressIndexOfPost(closestPost);
+          topicProgressController.set('progressPosition', progress);
           Discourse.PostView.considerHighlighting(topicController, closest);
         }).then(function() {
           Discourse.URL.jumpToPost(closest);

app/assets/javascripts/discourse/models/post_stream.js

@@ -635,13 +635,61 @@ Discourse.PostStream = Em.Object.extend({
     });
   },
 
+  /**
+    Returns the closest post given a postNumber that may not exist in the stream.
+    For example, if the user asks for a post that's deleted or otherwise outside the range.
+    This allows us to set the progress bar with the correct number.
+
+    @method closestPostForPostNumber
+    @param {Number} postNumber the post number we're looking for
+    @return {Post} the closest post
+    @see PostStream.closestPostNumberFor
+  **/
+  closestPostForPostNumber: function(postNumber) {
+    if (!this.get('hasPosts')) { return; }
+
+    var closest = null;
+    this.get('posts').forEach(function (p) {
+      if (closest === postNumber) { return; }
+      if (!closest) { closest = p; }
+
+      if (Math.abs(postNumber - p.get('post_number')) < Math.abs(closest.get('post_number') - postNumber)) {
+        closest = p;
+      }
+    });
+
+    return closest;
+  },
+
+  /**
+    Get the index of a post in the stream. (Use this for the topic progress bar.)
+
+    @param post the post to get the index of
+    @returns {Number} 1-starting index of the post, or 0 if not found
+    @see PostStream.progressIndexOfPostId
+  **/
+  progressIndexOfPost: function(post) {
+    return this.progressIndexOfPostId(post.get('id'));
+  },
+
+  /**
+    Get the index in the stream of a post id. (Use this for the topic progress bar.)
+
+    @param post_id - post id to search for
+    @returns {Number} 1-starting index of the post, or 0 if not found
+  **/
+  progressIndexOfPostId: function(post_id) {
+    return this.get('stream').indexOf(post_id) + 1;
+  },
+
   /**
     Returns the closest post number given a postNumber that may not exist in the stream.
     For example, if the user asks for a post that's deleted or otherwise outside the range.
     This allows us to set the progress bar with the correct number.
 
     @method closestPostNumberFor
-    @param {Integer} postNumber the post number we're looking for
+    @param {Number} postNumber the post number we're looking for
+    @return {Number} a close post number
   **/
   closestPostNumberFor: function(postNumber) {
     if (!this.get('hasPosts')) { return; }

app/assets/javascripts/discourse/routes/topic_from_params_route.js

@@ -23,7 +23,9 @@ Discourse.TopicFromParamsRoute = Discourse.Route.extend({
 
     postStream.refresh(params).then(function () {
       // The post we requested might not exist. Let's find the closest post
-      var closest = postStream.closestPostNumberFor(params.nearPost) || 1;
+      var closestPost = postStream.closestPostForPostNumber(params.nearPost || 1),
+          closest = closestPost.get('post_number'),
+          progress = postStream.progressIndexOfPost(closestPost);
 
       topicController.setProperties({
         currentPost: closest,
@@ -32,7 +34,7 @@ Discourse.TopicFromParamsRoute = Discourse.Route.extend({
       });
 
       topicProgressController.setProperties({
-        progressPosition: closest,
+        progressPosition: progress,
         expanded: false
       });
       Discourse.URL.jumpToPost(closest);