add diff link on wiki page versions (#1622)

app/models/wiki_page_version.rb

@@ -4,6 +4,8 @@ class WikiPageVersion < ApplicationRecord
   belongs_to :artist, optional: true
   delegate :visible?, :to => :wiki_page
 
+  extend Memoist
+
   module SearchMethods
     def for_user(user_id)
       where("updater_id = ?", user_id)
@@ -35,6 +37,11 @@ class WikiPageVersion < ApplicationRecord
     title.tr("_", " ")
   end
 
+  def previous
+    WikiPageVersion.where("wiki_page_id = ? and id < ?", wiki_page_id, id).order("id desc").first
+  end
+  memoize :previous
+
   def category_name
     Tag.category_for(title)
   end

app/views/wiki_pages/_secondary_links.html.erb

@@ -1,7 +1,9 @@
 <% content_for(:secondary_links) do %>
   <menu>
     <li><%= render "wiki_pages/quick_search" %></li>
+
     <%= subnav_link_to "Listing", wiki_pages_path %>
+
     <%= subnav_link_to "Search", search_wiki_pages_path %>
     
     <% if CurrentUser.is_member? %>
@@ -12,20 +14,33 @@
     
     <% if @wiki_page && @wiki_page.new_record? && @wiki_page.try(:tag).present? %>
       <li>|</li>
+
       <%= subnav_link_to "Posts (#{@wiki_page.tag.post_count})", posts_path(:tags => @wiki_page.title) %>
+
     <% elsif @wiki_page && !@wiki_page.new_record? %>
       <li>|</li>
+
       <%= subnav_link_to "Posts (#{@wiki_page.tag.try(:post_count) || 0})", posts_path(:tags => @wiki_page.title) %>
+
       <%= subnav_link_to "History", wiki_page_versions_path(:search => {:wiki_page_id => @wiki_page.id}) %>
+
       <% if CurrentUser.is_member? %>
         <%= subnav_link_to "Edit", edit_wiki_page_path(@wiki_page), "data-shortcut": "e" %>
       <% end %>
+
       <% if CurrentUser.is_builder? && !@wiki_page.is_deleted? %>
         <%= subnav_link_to "Delete", wiki_page_path(@wiki_page), :remote => true, :method => :delete, :"data-shortcut" => "shift+d", :"data-confirm" => "Are you sure you want to delete this wiki page?" %>
       <% end %>
+
     <% elsif @wiki_page_version %>
       <li>|</li>
+
       <%= subnav_link_to "Newest", wiki_page_path(@wiki_page_version.wiki_page_id) %>
+
+      <% if @wiki_page_version.previous %>
+        <%= subnav_link_to "Diff", diff_wiki_page_versions_path(:otherpage => @wiki_page_version.id, :thispage => @wiki_page_version.previous.id) %>
+      <% end %>
+
       <% if CurrentUser.is_member? %>
         <%= subnav_link_to "Revert to", revert_wiki_page_path(@wiki_page_version.wiki_page_id, :version_id => @wiki_page_version.id), :method => :put, :data => {:confirm => "Are you sure you want to revert to this version?"} %>
       <% end %>

public/robots.txt

@@ -51,4 +51,4 @@ Disallow: /users
 Disallow: /wiki_page_versions
 Disallow: /wiki_pages/new
 Disallow: /wiki_pages/revert
-Disallow: /wiki_pages/show_or_new
+Disallow: /wiki_pages/show_or_new