Merge branch 'issue_4271' into 'master'

Add button to toggle whitespace changes

Closes #4271 

**Merge Request**

<img src="/uploads/ea857269faed38a25b63b768d7f3a85b/Screen_Shot_2016-03-23_at_11.32.41_AM.png" width="1157" />


**Diff view**

<img src="/uploads/bc2ac3e4855584f9214c8f3ddf325b06/Screen_Shot_2016-03-23_at_11.32.53_AM.png" width="1211" />

See merge request !3367

3 files changed, 35 insertions, 2 deletions

diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index 97466d532f4..9f73edb4553 100644
--- a/app/helpers/diff_helper.rb
+++ b/app/helpers/diff_helper.rb
@@ -23,7 +23,7 @@ module DiffHelper
   end
 
   def diff_options
-    options = { ignore_whitespace_change: params[:w] == '1' }
+    options = { ignore_whitespace_change: hide_whitespace? }
     if diff_hard_limit_enabled?
       options.merge!(Commit.max_diff_options)
     end
@@ -128,4 +128,31 @@ module DiffHelper
       title
     end
   end
+
+  def commit_diff_whitespace_link(project, commit, options)
+    url = namespace_project_commit_path(project.namespace, project, commit.id, params_with_whitespace)
+    toggle_whitespace_link(url, options)
+  end
+
+  def diff_merge_request_whitespace_link(project, merge_request, options)
+    url = diffs_namespace_project_merge_request_path(project.namespace, project, merge_request, params_with_whitespace)
+    toggle_whitespace_link(url, options)
+  end
+
+  private
+
+  def hide_whitespace?
+    params[:w] == '1'
+  end
+
+  def params_with_whitespace
+    hide_whitespace? ? request.query_parameters.except(:w) : request.query_parameters.merge(w: 1)
+  end
+
+  def toggle_whitespace_link(url, options)
+    options[:class] ||= ''
+    options[:class] << ' btn btn-default'
+
+    link_to "#{hide_whitespace? ? 'Show' : 'Hide'} whitespace changes", url, class: options[:class]
+  end
 end
diff --git a/app/views/projects/diffs/_diffs.html.haml b/app/views/projects/diffs/_diffs.html.haml
index eaab99973a4..d9c4b410d32 100644
--- a/app/views/projects/diffs/_diffs.html.haml
+++ b/app/views/projects/diffs/_diffs.html.haml
@@ -1,3 +1,4 @@
+- show_whitespace_toggle = local_assigns.fetch(:show_whitespace_toggle, true)
 - if diff_view == 'parallel'
   - fluid_layout true
 
@@ -5,6 +6,11 @@
 
 .content-block.oneline-block.files-changed
   .inline-parallel-buttons
+    - if show_whitespace_toggle
+      - if current_controller?(:commit)
+        = commit_diff_whitespace_link(@project, @commit, class: 'hidden-xs')
+      - elsif current_controller?(:merge_requests)
+        = diff_merge_request_whitespace_link(@project, @merge_request, class: 'hidden-xs')
     .btn-group
       = inline_diff_btn
       = parallel_diff_btn
diff --git a/app/views/projects/merge_requests/_new_submit.html.haml b/app/views/projects/merge_requests/_new_submit.html.haml
index 2f14a91e64f..18b3f9e1549 100644
--- a/app/views/projects/merge_requests/_new_submit.html.haml
+++ b/app/views/projects/merge_requests/_new_submit.html.haml
@@ -42,7 +42,7 @@
           %h4 This comparison includes more than #{MergeRequestDiff::COMMITS_SAFE_SIZE} commits.
           %p To preserve performance the line changes are not shown.
       - else
-        = render "projects/diffs/diffs", diffs: @diffs, project: @project, diff_refs: @merge_request.diff_refs
+        = render "projects/diffs/diffs", diffs: @diffs, project: @project, diff_refs: @merge_request.diff_refs, show_whitespace_toggle: false
     - if @ci_commit
       #builds.builds.tab-pane
         = render "projects/merge_requests/show/builds"