3 files changed, 59 insertions, 0 deletions
diff --git a/lib/api/api.rb b/lib/api/api.rb
index d43af3f24e9..aa34110c34b 100644
--- a/lib/api/api.rb
+++ b/lib/api/api.rb
@@ -73,5 +73,6 @@ module API
     mount ::API::Triggers
     mount ::API::Users
     mount ::API::Variables
+    mount ::API::MergeRequestDiffs
   end
 end
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index ae74d14a4bb..b305fce9fcf 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -230,6 +230,19 @@ module API
       end
     end
 
+    class MergeRequestDiff < Grape::Entity
+      expose :id, :head_commit_sha, :base_commit_sha, :start_commit_sha,
+        :created_at, :merge_request_id, :state, :real_size
+    end
+
+    class MergeRequestDiffFull < MergeRequestDiff
+      expose :commits, using: Entities::RepoCommit
+
+      expose :diffs, using: Entities::RepoDiff do |compare, _|
+        compare.diffs(all_diffs: true).to_a
+      end
+    end
+
     class SSHKey < Grape::Entity
       expose :id, :title, :key, :created_at
     end
diff --git a/lib/api/merge_request_diffs.rb b/lib/api/merge_request_diffs.rb
new file mode 100644
index 00000000000..07435d78468
--- /dev/null
+++ b/lib/api/merge_request_diffs.rb
@@ -0,0 +1,45 @@
+module API
+  # MergeRequestDiff API
+  class MergeRequestDiffs < Grape::API
+    before { authenticate! }
+
+    resource :projects do
+      desc 'Get a list of merge request diff versions' do
+        detail 'This feature was introduced in GitLab 8.12.'
+        success Entities::MergeRequestDiff
+      end
+
+      params do
+        requires :id, type: String, desc: 'The ID of a project'
+        requires :merge_request_id, type: Integer, desc: 'The ID of a merge request'
+      end
+
+      get ":id/merge_requests/:merge_request_id/versions" do
+        merge_request = user_project.merge_requests.
+          find(params[:merge_request_id])
+
+        authorize! :read_merge_request, merge_request
+        present merge_request.merge_request_diffs, with: Entities::MergeRequestDiff
+      end
+
+      desc 'Get a single merge request diff version' do
+        detail 'This feature was introduced in GitLab 8.12.'
+        success Entities::MergeRequestDiffFull
+      end
+
+      params do
+        requires :id, type: String, desc: 'The ID of a project'
+        requires :merge_request_id, type: Integer, desc: 'The ID of a merge request'
+        requires :version_id, type: Integer, desc: 'The ID of a merge request diff version'
+      end
+
+      get ":id/merge_requests/:merge_request_id/versions/:version_id" do
+        merge_request = user_project.merge_requests.
+          find(params[:merge_request_id])
+
+        authorize! :read_merge_request, merge_request
+        present merge_request.merge_request_diffs.find(params[:version_id]), with: Entities::MergeRequestDiffFull
+      end
+    end
+  end
+end