fixes #1289

app/controllers/forum_topics_controller.rb

@@ -1,6 +1,7 @@
 class ForumTopicsController < ApplicationController
   respond_to :html, :xml, :json
   before_filter :member_only, :except => [:index, :show]
+  before_filter :janitor_only, :only => [:new_merge, :create_merge]
   before_filter :normalize_search, :only => :index
 
   def new
@@ -68,6 +69,17 @@ class ForumTopicsController < ApplicationController
     redirect_to forum_topics_path, :notice => "All topics marked as read"
   end
 
+  def new_merge
+    @forum_topic = ForumTopic.find(params[:id])
+  end
+
+  def create_merge
+    @forum_topic = ForumTopic.find(params[:id])
+    @merged_topic = ForumTopic.find(params[:merged_id])
+    @forum_topic.merge(@merged_topic)
+    redirect_to forum_topic_path(@forum_topic)
+  end
+
 private
   def normalize_search
     if params[:title_matches]

app/models/forum_topic.rb

@@ -130,4 +130,9 @@ class ForumTopic < ActiveRecord::Base
     end
     result
   end
+
+  def merge(topic)
+    ForumPost.update_all({:topic_id => id}, :id => topic.posts.map(&:id))
+    update_attribute(:is_deleted, true)
+  end
 end

app/views/forum_topics/_secondary_links.html.erb

@@ -31,6 +31,7 @@
           <% else %>
             <li><%= link_to "Sticky", forum_topic_path(@forum_topic, :forum_topic => {:is_sticky => true}), :method => :put, :confirm => "Are you sure you want to sticky this forum topic?" %></li>
           <% end %>
+          <li><%= link_to "Merge", new_merge_forum_topic_path(@forum_topic) %></li>
         <% end %>
       <% end %>
     <% end %>

app/views/forum_topics/new_merge.html.erb

@@ -0,0 +1,23 @@
+<div id="c-forum-topics">
+  <div id="a-merge">
+    <h1>Merge Forum Topic</h1>
+
+    <p>Merge <strong><%= @forum_topic.title %></strong> into:</p>
+
+    <%= form_tag(create_merge_forum_topic_path(@forum_topic)) do %>
+      <div>
+        <label>
+          Forum Topic ID:
+          <%= text_field_tag :merged_id %>
+        </label>
+      </div>
+      <%= submit_tag "Merge" %>
+    <% end %>
+  </div>
+</div>
+
+<%= render "secondary_links" %>
+
+<% content_for(:page_title) do %>
+  Merge Forum Topic - <%= Danbooru.config.app_name %>
+<% end %>