FIX: Moving posts was not updating reply_count and

`reply_to_post_number` so reply linkage was broken.

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

@@ -376,16 +376,16 @@ Discourse.Post = Discourse.Model.extend({
 
   // Whether to show replies directly below
   showRepliesBelow: function() {
-    var reply_count = this.get('reply_count');
+    var replyCount = this.get('reply_count');
 
     // We don't show replies if there aren't any
-    if (reply_count === 0) return false;
+    if (replyCount === 0) return false;
 
     // Always show replies if the setting `suppress_reply_directly_below` is false.
     if (!Discourse.SiteSettings.suppress_reply_directly_below) return true;
 
     // Always show replies if there's more than one
-    if (reply_count > 1) return true;
+    if (replyCount > 1) return true;
 
     // If we have *exactly* one reply, we have to consider if it's directly below us
     var topic = this.get('topic');

app/models/post_mover.rb

@@ -46,32 +46,50 @@ class PostMover
   end
 
   def move_each_post
-    with_max_post_number do |max_post_number|
-      posts.each_with_index do |post, offset|
-        post.is_first_post? ? copy(post) : move(post, offset + max_post_number)
+    max_post_number = destination_topic.max_post_number + 1
+
+    @move_map = {}
+    @reply_count = {}
+    posts.each_with_index do |post, offset|
+      unless post.is_first_post?
+        @move_map[post.post_number] = offset + max_post_number
+      else
+        @move_map[post.post_number] = 1
       end
+      if post.reply_to_post_number.present?
+        @reply_count[post.reply_to_post_number] = (@reply_count[post.reply_to_post_number] || 0) + 1
+      end
+    end
+
+    posts.each do |post|
+      post.is_first_post? ? create_first_post(post) : move(post)
     end
   end
 
-  def copy(post)
-    PostCreator.create(
+  def create_first_post(post)
+    p = PostCreator.create(
       post.user,
       raw: post.raw,
       topic_id: destination_topic.id,
       acting_user: user
     )
+    p.update_column(:reply_count, @reply_count[1] || 0)
   end
 
-  def move(post, post_number)
+  def move(post)
     @first_post_number_moved ||= post.post_number
 
     Post.where(id: post.id, topic_id: original_topic.id).update_all(
       [
         ['post_number = :post_number',
+         'reply_to_post_number = :reply_to_post_number',
          'topic_id    = :topic_id',
-         'sort_order  = :post_number'
+         'sort_order  = :post_number',
+         'reply_count = :reply_count',
         ].join(', '),
-        post_number: post_number,
+        reply_count: @reply_count[post.post_number] || 0,
+        post_number: @move_map[post.post_number],
+        reply_to_post_number: @move_map[post.reply_to_post_number],
         topic_id: destination_topic.id
       ]
     )
@@ -112,10 +130,6 @@ class PostMover
     )
   end
 
-  def with_max_post_number
-    yield destination_topic.max_post_number + 1
-  end
-
   def posts
     @posts ||= begin
       Post.where(id: post_ids).order(:created_at).tap do |posts|

spec/models/post_mover_spec.rb

@@ -8,9 +8,9 @@ describe PostMover do
     let(:category) { Fabricate(:category, user: user) }
     let!(:topic) { Fabricate(:topic, user: user) }
     let!(:p1) { Fabricate(:post, topic: topic, user: user) }
-    let!(:p2) { Fabricate(:post, topic: topic, user: another_user, raw: "Has a link to [evil trout](http://eviltrout.com) which is a cool site.")}
-    let!(:p3) { Fabricate(:post, topic: topic, user: user)}
-    let!(:p4) { Fabricate(:post, topic: topic, user: user)}
+    let!(:p2) { Fabricate(:post, topic: topic, user: another_user, raw: "Has a link to [evil trout](http://eviltrout.com) which is a cool site.", reply_to_post_number: p1.post_number)}
+    let!(:p3) { Fabricate(:post, topic: topic, reply_to_post_number: p1.post_number, user: user)}
+    let!(:p4) { Fabricate(:post, topic: topic, reply_to_post_number: p2.post_number, user: user)}
 
     before do
       # add a like to a post, enable observers so we get user actions
@@ -120,11 +120,15 @@ describe PostMover do
           p2.sort_order.should == 2
           p2.post_number.should == 2
           p2.topic_id.should == moved_to.id
+          p2.reply_count.should == 1
+          p2.reply_to_post_number.should be_nil
 
           p4.reload
           p4.post_number.should == 3
           p4.sort_order.should == 3
           p4.topic_id.should == moved_to.id
+          p4.reply_count.should == 0
+          p4.reply_to_post_number.should == 2
 
           # Check out the original topic
           topic.reload
@@ -159,12 +163,19 @@ describe PostMover do
           p1.sort_order.should == 1
           p1.post_number.should == 1
           p1.topic_id == topic.id
+          p1.reply_count.should == 0
+
+          # New first post
+          new_first = new_topic.posts.where(post_number: 1).first
+          new_first.reply_count.should == 1
 
           # Second post is in a new topic
           p2.reload
           p2.post_number.should == 2
           p2.sort_order.should == 2
           p2.topic_id == new_topic.id
+          p2.reply_to_post_number.should == 1
+          p2.reply_count.should == 0
 
           topic.reload
           topic.posts.by_post_number.should =~ [p1, p3, p4]
@@ -195,11 +206,14 @@ describe PostMover do
           p2.sort_order.should == 3
           p2.post_number.should == 3
           p2.topic_id.should == moved_to.id
+          p2.reply_count.should == 1
+          p2.reply_to_post_number.should be_nil
 
           p4.reload
           p4.post_number.should == 4
           p4.sort_order.should == 4
           p4.topic_id.should == moved_to.id
+          p4.reply_to_post_number.should == p2.post_number
         end
       end