View old versions of pages.

lib/gollum/frontend/app.rb

@@ -73,6 +73,19 @@ module Precious
       redirect "/#{page}"
     end
 
+    get %r{/(.+?)/([0-9a-f]{40})} do
+      name = params[:captures][0]
+      wiki = Gollum::Wiki.new($path)
+      if page = wiki.page(name, params[:captures][1])
+        @page = page
+        @name = name
+        @content = page.formatted_data
+        mustache :page
+      else
+        halt 404
+      end
+    end
+
     get '/*' do
       show_page_or_file(params[:splat].first)
     end

lib/gollum/frontend/templates/page.mustache

@@ -20,7 +20,7 @@
     <small>Versions:</small>
     <select id="versions_select" name="versions_select">
       {{#versions}}
-        <option value="{{id}}">Version {{num}} ({{id7}}) by {{author}}</option>
+        <option {{#selected}}selected="true" {{/selected}}value="/{{name}}/{{id}}">Version {{num}} ({{id7}}) by {{author}}</option>
       {{/versions}}
     </select>
   </div>

lib/gollum/frontend/views/page.rb

@@ -26,6 +26,7 @@ module Precious
           { :id => v.id,
             :id7 => v.id[0..6],
             :num => i,
+            :selected => @page.version.id == v.id,
             :author => v.author.name }
         end
       end