10 files changed, 70 insertions, 3 deletions

diff --git a/lib/gitlab/email/attachment_uploader.rb b/lib/gitlab/email/attachment_uploader.rb
index 83440ae227d..a826519b2dd 100644
--- a/lib/gitlab/email/attachment_uploader.rb
+++ b/lib/gitlab/email/attachment_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     class AttachmentUploader
diff --git a/lib/gitlab/email/handler/create_merge_request_handler.rb b/lib/gitlab/email/handler/create_merge_request_handler.rb
index e68ae60ff98..5772727e855 100644
--- a/lib/gitlab/email/handler/create_merge_request_handler.rb
+++ b/lib/gitlab/email/handler/create_merge_request_handler.rb
@@ -44,10 +44,26 @@ module Gitlab
           @project ||= Project.find_by_full_path(project_path)
         end
 
+        def metrics_params
+          super.merge(includes_patches: patch_attachments.any?)
+        end
+
         private
 
+        def build_merge_request
+          MergeRequests::BuildService.new(project, author, merge_request_params).execute
+        end
+
         def create_merge_request
-          merge_request = MergeRequests::BuildService.new(project, author, merge_request_params).execute
+          merge_request = build_merge_request
+
+          if patch_attachments.any?
+            apply_patches_to_source_branch(start_branch: merge_request.target_branch)
+            remove_patch_attachments
+            # Rebuild the merge request as the source branch might just have
+            # been created, so we should re-validate.
+            merge_request = build_merge_request
+          end
 
           if merge_request.errors.any?
             merge_request
@@ -59,12 +75,42 @@ module Gitlab
         def merge_request_params
           params = {
             source_project_id: project.id,
-            source_branch: mail.subject,
+            source_branch: source_branch,
             target_project_id: project.id
           }
           params[:description] = message if message.present?
           params
         end
+
+        def apply_patches_to_source_branch(start_branch:)
+          patches = patch_attachments.map { |patch| patch.body.decoded }
+
+          result = Commits::CommitPatchService
+                     .new(project, author, branch_name: source_branch, patches: patches, start_branch: start_branch)
+                     .execute
+
+          if result[:status] != :success
+            message = "Could not apply patches to #{source_branch}:\n#{result[:message]}"
+            raise InvalidAttachment, message
+          end
+        end
+
+        def remove_patch_attachments
+          patch_attachments.each { |patch| mail.parts.delete(patch) }
+          # reset the message, so it needs to be reporocessed when the attachments
+          # have been modified
+          @message = nil
+        end
+
+        def patch_attachments
+          @patches ||= mail.attachments
+                         .select { |attachment| attachment.filename.ends_with?('.patch') }
+                         .sort_by(&:filename)
+        end
+
+        def source_branch
+          @source_branch ||= mail.subject
+        end
       end
     end
   end
diff --git a/lib/gitlab/email/hook/additional_headers_interceptor.rb b/lib/gitlab/email/hook/additional_headers_interceptor.rb
index 064cb5e659a..aa2ef76069b 100644
--- a/lib/gitlab/email/hook/additional_headers_interceptor.rb
+++ b/lib/gitlab/email/hook/additional_headers_interceptor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook
diff --git a/lib/gitlab/email/hook/delivery_metrics_observer.rb b/lib/gitlab/email/hook/delivery_metrics_observer.rb
index 1c2985f6045..c7af485fcc5 100644
--- a/lib/gitlab/email/hook/delivery_metrics_observer.rb
+++ b/lib/gitlab/email/hook/delivery_metrics_observer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook
diff --git a/lib/gitlab/email/hook/disable_email_interceptor.rb b/lib/gitlab/email/hook/disable_email_interceptor.rb
index 7bb8b53f0c8..6b6b1d85109 100644
--- a/lib/gitlab/email/hook/disable_email_interceptor.rb
+++ b/lib/gitlab/email/hook/disable_email_interceptor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook
diff --git a/lib/gitlab/email/hook/email_template_interceptor.rb b/lib/gitlab/email/hook/email_template_interceptor.rb
index be0c4dd862e..13f8db2051d 100644
--- a/lib/gitlab/email/hook/email_template_interceptor.rb
+++ b/lib/gitlab/email/hook/email_template_interceptor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook
diff --git a/lib/gitlab/email/html_parser.rb b/lib/gitlab/email/html_parser.rb
index 50559a48973..77f299bcade 100644
--- a/lib/gitlab/email/html_parser.rb
+++ b/lib/gitlab/email/html_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     class HTMLParser
diff --git a/lib/gitlab/email/message/repository_push.rb b/lib/gitlab/email/message/repository_push.rb
index cd9d3a6483f..ec412e7a8b1 100644
--- a/lib/gitlab/email/message/repository_push.rb
+++ b/lib/gitlab/email/message/repository_push.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Message
@@ -116,7 +118,7 @@ module Gitlab
         end
 
         def subject
-          subject_text = '[Git]'
+          subject_text = ['[Git]']
           subject_text << "[#{project.full_path}]"
           subject_text << "[#{ref_name}]" if @action == :push
           subject_text << ' '
@@ -134,6 +136,8 @@ module Gitlab
             subject_action[0] = subject_action[0].capitalize
             subject_text << "#{subject_action} #{ref_type} #{ref_name}"
           end
+
+          subject_text.join
         end
       end
     end
diff --git a/lib/gitlab/email/receiver.rb b/lib/gitlab/email/receiver.rb
index d8c594ad0e7..d28f6b301fa 100644
--- a/lib/gitlab/email/receiver.rb
+++ b/lib/gitlab/email/receiver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'gitlab/email/handler'
 
 # Inspired in great part by Discourse's Email::Receiver
@@ -18,6 +20,7 @@ module Gitlab
     InvalidIssueError = Class.new(InvalidRecordError)
     InvalidMergeRequestError = Class.new(InvalidRecordError)
     UnknownIncomingEmail = Class.new(ProcessingError)
+    InvalidAttachment = Class.new(ProcessingError)
 
     class Receiver
       def initialize(raw)
diff --git a/lib/gitlab/email/reply_parser.rb b/lib/gitlab/email/reply_parser.rb
index ae6b84607d6..2743f011ca6 100644
--- a/lib/gitlab/email/reply_parser.rb
+++ b/lib/gitlab/email/reply_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Inspired in great part by Discourse's Email::Receiver
 module Gitlab
   module Email