add wiki diff

Gemfile

@@ -31,6 +31,7 @@ gem 'net-ssh'
 gem 'net-sftp'
 gem 'newrelic_rpm'
 gem 'term-ansicolor', :require => "term/ansicolor"
+gem 'diff-lcs', :require => "diff/lcs/array"
 
 group :development do
   gem 'ruby-prof'

Gemfile.lock

@@ -66,6 +66,7 @@ GEM
     delayed_job_active_record (0.4.1)
       activerecord (>= 2.1.0, < 4)
       delayed_job (~> 3.0)
+    diff-lcs (1.2.1)
     domain_name (0.5.7)
       unf (~> 0.0.3)
     erubis (2.7.0)
@@ -188,6 +189,7 @@ DEPENDENCIES
   daemons
   delayed_job
   delayed_job_active_record
+  diff-lcs
   factory_girl
   ffaker!
   mechanize!

app/assets/stylesheets/specific/wiki_pages.css.scss

@@ -7,4 +7,18 @@ div#c-wiki-pages {
     float: left;
     width: 30em;
   }
+  
+  del {
+    background: #FCC;
+    text-decoration: none;
+  }
+
+  ins {
+    background: #CFC;
+    text-decoration: none;
+  }
+  
+  table {
+    margin-bottom: 1em;
+  }
 }

app/controllers/wiki_page_versions_controller.rb

@@ -10,4 +10,9 @@ class WikiPageVersionsController < ApplicationController
     @wiki_page_version = WikiPageVersion.find(params[:id])
     respond_with(@wiki_page_version)
   end
+  
+  def diff
+    @thispage = WikiPageVersion.find(params[:thispage])
+    @otherpage = WikiPageVersion.find(params[:otherpage])
+  end
 end

app/helpers/wiki_page_versions_helper.rb

@@ -1,2 +1,51 @@
 module WikiPageVersionsHelper
+  def wiki_page_diff(thispage, otherpage)
+    pattern = Regexp.new('(?:<.+?>)|(?:\w+)|(?:[ \t]+)|(?:\r?\n)|(?:.+?)')
+
+    thisarr = thispage.body.scan(pattern)
+    otharr = otherpage.body.scan(pattern)
+
+    cbo = Diff::LCS::ContextDiffCallbacks.new
+    diffs = thisarr.diff(otharr, cbo)
+
+    escape_html = lambda {|str| str.gsub(/&/,'&amp;').gsub(/</,'&lt;').gsub(/>/,'&gt;')}
+
+    output = thisarr
+    output.each { |q| q.replace(escape_html[q]) }
+
+    diffs.reverse_each do |hunk|
+      newchange = hunk.max{|a,b| a.old_position <=> b.old_position}
+      newstart = newchange.old_position
+      oldstart = hunk.min{|a,b| a.old_position <=> b.old_position}.old_position
+
+      if newchange.action == '+'
+        output.insert(newstart, '</ins>')
+      end
+
+      hunk.reverse_each do |chg|
+        case chg.action
+        when '-'
+          oldstart = chg.old_position
+          output[chg.old_position] = '<br>' if chg.old_element.match(/^\r?\n$/)
+        when '+'
+          if chg.new_element.match(/^\r?\n$/)
+            output.insert(chg.old_position, '<br>')
+          else
+            output.insert(chg.old_position, "#{escape_html[chg.new_element]}")
+          end
+        end
+      end
+
+      if newchange.action == '+'
+        output.insert(newstart, '<ins>')
+      end
+
+      if hunk[0].action == '-'
+        output.insert((newstart == oldstart || newchange.action != '+') ? newstart+1 : newstart, '</del>')
+        output.insert(oldstart, '<del>')
+      end
+    end
+
+    output.join.gsub(/\r?\n/, '<br>').html_safe
+  end
 end

app/views/wiki_page_versions/diff.html.erb

@@ -0,0 +1,13 @@
+<div id="c-wiki-pages">
+  <div id="a-diff">
+    <h1>Wiki Page: <%= @thispage.title %></h1>
+
+    <p>Showing differences between <%= compact_time @thispage.created_at %> (<%= link_to @thispage.updater.name, user_path(@thispage.updater) %>) and <%= compact_time @otherpage.created_at %> (<%= link_to @otherpage.updater.name, user_path(@otherpage.updater) %>)</p>
+
+    <div>
+      <%= wiki_page_diff(@thispage, @otherpage) %>
+    </div>
+  </div>
+</div>
+
+<%= render "wiki_pages/secondary_links" %>

app/views/wiki_page_versions/index.html.erb

@@ -5,34 +5,42 @@
     <section id="content">
       <h1>Wiki Pages</h1>
       
-      <table width="100%" class="striped">
+      <%= form_tag(diff_wiki_page_versions_path, :method => :get) do %>
-        <thead>
+        <table width="100%" class="striped">
-          <tr>
+          <thead>
-            <th width="60%">Title</th>
-            <th width="10%">IP Address</th>
-            <th width="30%">Last edited</th>
-          </tr>       
-        </thead>
-        <tbody>
-          <% @wiki_page_versions.each do |wiki_page_version| %>
             <tr>
-              <td><%= wiki_page_version.title %></td>
+              <th width="2%"></th>
-              <td>
+              <th width="2%"></th>
-                <% if CurrentUser.is_admin? %>
+              <th width="60%">Title</th>
-                  <%= wiki_page_version.updater_ip_addr %>
+              <th width="10%">IP Address</th>
-                <% end %>
+              <th width="26%">Last edited</th>
-              </td>
-              <td>
-                <%= link_to wiki_page_version.updated_at.strftime("%Y-%m-%d %I:%M"), wiki_page_version_path(wiki_page_version) %>
-                <% if wiki_page_version.updater %>
-                  by
-                  <%= link_to wiki_page_version.updater_name, user_path(wiki_page_version.updater) %>
-                <% end %>
-              </td>
             </tr>       
-          <% end %>       
+          </thead>
-        </tbody>
+          <tbody>
-      </table>
+            <% @wiki_page_versions.each do |wiki_page_version| %>
+              <tr>
+                <td><%= radio_button_tag "thispage", wiki_page_version.id %></td>
+                <td><%= radio_button_tag "otherpage", wiki_page_version.id %></td>
+                <td><%= wiki_page_version.title %></td>
+                <td>
+                  <% if CurrentUser.is_admin? %>
+                    <%= wiki_page_version.updater_ip_addr %>
+                  <% end %>
+                </td>
+                <td>
+                  <%= link_to wiki_page_version.updated_at.strftime("%Y-%m-%d %I:%M"), wiki_page_version_path(wiki_page_version) %>
+                  <% if wiki_page_version.updater %>
+                    by
+                    <%= link_to wiki_page_version.updater_name, user_path(wiki_page_version.updater) %>
+                  <% end %>
+                </td>
+              </tr>
+            <% end %>       
+          </tbody>
+        </table>
+        
+        <%= submit_tag "Diff" %>
+      <% end %>
       
       <%= numbered_paginator(@wiki_page_versions) %>
     </section>

config/routes.rb

@@ -193,7 +193,11 @@ Danbooru::Application.routes.draw do
       get :show_or_new
     end
   end
-  resources :wiki_page_versions, :only => [:index, :show]
+  resources :wiki_page_versions, :only => [:index, :show, :diff] do
+    collection do
+      get :diff
+    end
+  end
   
   # aliases
   resources :wpages, :controller => "wiki_pages"