Render rebase button and ff merge button

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/models/merge_request.rb

@@ -498,4 +498,12 @@ class MergeRequest < ActiveRecord::Base
       unlock_mr if locked?
     end
   end
+
+  def source_sha_parent
+    source_project.repository.commit(source_sha).parents.first.sha
+  end
+
+  def ff_merge_possible?
+    target_sha == source_sha_parent
+  end
 end

app/views/projects/merge_requests/widget/_open.html.haml

@@ -17,6 +17,8 @@
       = render 'projects/merge_requests/widget/open/not_allowed'
     - elsif @merge_request.requires_approve? && !@merge_request.approved?
       = render 'projects/merge_requests/widget/open/approve'
+    - elsif @project.merge_requests_ff_only_enabled
+      = render 'projects/merge_requests/widget/open/ff_accept'
     - elsif @merge_request.can_be_merged?
       = render 'projects/merge_requests/widget/open/accept'
 

app/views/projects/merge_requests/widget/open/_accept.html.haml

@@ -9,11 +9,6 @@
         = label_tag :should_remove_source_branch, class: "remove_source_checkbox" do
           = check_box_tag :should_remove_source_branch
           Remove source branch
-    - if @merge_request.target_project.merge_requests_rebase_enabled && can_rebase?(@merge_request.target_project, @merge_request.target_branch)
-      .accept-control.remove_branch_holder.checkbox
-        = label_tag :should_rebase do
-          = check_box_tag :should_rebase, "1", @project.merge_requests_rebase_default
-          Rebase before merge
 
     .accept-control
       = link_to "#", class: "modify-merge-commit-link js-toggle-button" do

app/views/projects/merge_requests/widget/open/_ff_accept.html.haml

+- if @merge_request.ff_merge_possible?
+  = form_for [:ff_merge, @project.namespace.becomes(Namespace), @project, @merge_request], remote: true, method: :post, html: { class: 'accept-mr-form js-requires-input' } do |f|
+    = hidden_field_tag :authenticity_token, form_authenticity_token
+    .accept-merge-holder.clearfix.js-toggle-container
+      .accept-action
+        = f.button class: "btn btn-create accept-mr" do
+          Accept Merge Request
+
+      .accept-control
+        Fast-forward merge without creating merge commit
+- else
+  = form_for [:rebase, @project.namespace.becomes(Namespace), @project, @merge_request],
+    remote: true, method: :post, html: { class: 'accept-mr-form js-requires-input' } do |f|
+    = hidden_field_tag :authenticity_token, form_authenticity_token
+    .accept-merge-holder.clearfix.js-toggle-container
+      - if @merge_request.target_project.merge_requests_rebase_enabled && can_rebase?(@merge_request.target_project, @merge_request.target_branch)
+        .accept-action
+          = f.button class: "btn btn-reopen rebase-mr" do
+            Rebase from #{@merge_request.target_branch}
+        .accept-control
+          Fast-forward merge is not possible. Branch must be rebased first
+
+:coffeescript
+  $('.accept-mr-form').on 'ajax:before', ->
+    btn = $('.accept-mr')
+    btn.disable()
+    btn.html("<i class='fa fa-spinner fa-spin'></i> Merge in progress")
+
+  $('.rebase-mr-form').on 'ajax:before', ->
+    btn = $('.rebase-mr')
+    btn.disable()
+    btn.html("<i class='fa fa-spinner fa-spin'></i> Rebase in progress. It could take some time")

config/routes.rb

@@ -505,6 +505,8 @@ Gitlab::Application.routes.draw do
             get :ci_status
             post :toggle_subscription
             post :approve
+            post :rebase
+            post :ff_merge
           end
 
           collection do