1 files changed, 20 insertions, 5 deletions

diff --git a/app/controllers/revisions_controller.rb b/app/controllers/revisions_controller.rb
index 42d667e..0aed243 100644
--- a/app/controllers/revisions_controller.rb
+++ b/app/controllers/revisions_controller.rb
@@ -13,16 +13,31 @@ class RevisionsController < ApplicationController
 
   def diff
     @node = Node.find(params[:node_id])
-    
+
     if @node.pages.length > 1
       params[:start_revision]  ||= @node.pages.all[-2].revision
       params[:end_revision]    ||= @node.pages.all[-1].revision
     else
-      params[:start], params[:end] = 1, 1
+      params[:start_revision], params[:end_revision] = 1, 1
+    end
+
+    @start = @node.resolve_page_reference(params[:start_revision])
+    @end   = @node.resolve_page_reference(params[:end_revision])
+
+    if @start.nil? || @end.nil?
+      flash[:error] = "That comparison is no longer available."
+      redirect_to(node_path(@node)) and return
     end
-    
-    @start  = @node.pages.find_by_revision( params[:start_revision] )
-    @end    = @node.pages.find_by_revision( params[:end_revision] )
+
+    @locale_summary  = @end.locale_diff_summary(@start)
+    requested_locale = params[:locale].presence&.to_sym
+    default_locale    = @locale_summary.find { |s| s[:changed] }&.dig(:locale) || I18n.default_locale
+    @locale = @locale_summary.any? { |s| s[:locale] == requested_locale } ? requested_locale : default_locale
+
+    @diff_view              = params[:view] == "side_by_side" ? :side_by_side : :inline
+    @diff                   = @end.diff_against(@start, view: @diff_view, locale: @locale)
+    @available_layer_pairs  = @node.available_layer_pairs
+    @locked_by_other        = @node.locked? && @node.lock_owner != current_user
   end
 
   def show