Merge branch 'mr-conflict-notification' into 'master'

MR unmergeable notification

See merge request gitlab-org/gitlab-ce!18042

10 files changed, 122 insertions, 24 deletions

diff --git a/app/mailers/emails/merge_requests.rb b/app/mailers/emails/merge_requests.rb
index b3f2aeb08ca..5ba3a4a322c 100644
--- a/app/mailers/emails/merge_requests.rb
+++ b/app/mailers/emails/merge_requests.rb
@@ -56,6 +56,14 @@ module Emails
       mail_answer_thread(@merge_request, merge_request_thread_options(updated_by_user_id, recipient_id, reason))
     end
 
+    def merge_request_unmergeable_email(recipient_id, merge_request_id, reason = nil)
+      setup_merge_request_mail(merge_request_id, recipient_id)
+
+      @reasons = MergeRequestPresenter.new(@merge_request, current_user: current_user).unmergeable_reasons
+
+      mail_answer_thread(@merge_request, merge_request_thread_options(@merge_request.author_id, recipient_id, reason))
+    end
+
     def resolved_all_discussions_email(recipient_id, merge_request_id, resolved_by_user_id, reason = nil)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 628c61d5d69..9c4384a6e42 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -104,24 +104,35 @@ class MergeRequest < ActiveRecord::Base
 
   state_machine :merge_status, initial: :unchecked do
     event :mark_as_unchecked do
-      transition [:can_be_merged, :cannot_be_merged] => :unchecked
+      transition [:can_be_merged, :unchecked] => :unchecked
+      transition [:cannot_be_merged, :cannot_be_merged_recheck] => :cannot_be_merged_recheck
     end
 
     event :mark_as_mergeable do
-      transition [:unchecked, :cannot_be_merged] => :can_be_merged
+      transition [:unchecked, :cannot_be_merged_recheck] => :can_be_merged
     end
 
     event :mark_as_unmergeable do
-      transition [:unchecked, :can_be_merged] => :cannot_be_merged
+      transition [:unchecked, :cannot_be_merged_recheck] => :cannot_be_merged
     end
 
     state :unchecked
+    state :cannot_be_merged_recheck
     state :can_be_merged
     state :cannot_be_merged
 
     around_transition do |merge_request, transition, block|
       Gitlab::Timeless.timeless(merge_request, &block)
     end
+
+    after_transition unchecked: :cannot_be_merged do |merge_request, transition|
+      NotificationService.new.merge_request_unmergeable(merge_request)
+      TodoService.new.merge_request_became_unmergeable(merge_request)
+    end
+
+    def check_state?(merge_status)
+      [:unchecked, :cannot_be_merged_recheck].include?(merge_status.to_sym)
+    end
   end
 
   validates :source_project, presence: true, unless: [:allow_broken, :importing?, :closed_without_fork?]
@@ -327,6 +338,16 @@ class MergeRequest < ActiveRecord::Base
     update_column(:merge_jid, jid)
   end
 
+  def merge_participants
+    participants = [author]
+
+    if merge_when_pipeline_succeeds? && !participants.include?(merge_user)
+      participants << merge_user
+    end
+
+    participants
+  end
+
   def first_commit
     merge_request_diff ? merge_request_diff.first_commit : compare_commits.first
   end
@@ -602,7 +623,7 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def check_if_can_be_merged
-    return unless unchecked? && Gitlab::Database.read_write?
+    return unless self.class.state_machines[:merge_status].check_state?(merge_status) && Gitlab::Database.read_write?
 
     can_be_merged =
       !broken? && project.repository.can_be_merged?(diff_head_sha, target_branch)
diff --git a/app/models/project_services/drone_ci_service.rb b/app/models/project_services/drone_ci_service.rb
index 71b10fc6bc1..a4bf427ac0b 100644
--- a/app/models/project_services/drone_ci_service.rb
+++ b/app/models/project_services/drone_ci_service.rb
@@ -115,6 +115,6 @@ class DroneCiService < CiService
 
   def merge_request_valid?(data)
     data[:object_attributes][:state] == 'opened' &&
-      data[:object_attributes][:merge_status] == 'unchecked'
+      MergeRequest.state_machines[:merge_status].check_state?(data[:object_attributes][:merge_status])
   end
 end
diff --git a/app/presenters/merge_request_presenter.rb b/app/presenters/merge_request_presenter.rb
index 4b4132af2d0..ad839d9840a 100644
--- a/app/presenters/merge_request_presenter.rb
+++ b/app/presenters/merge_request_presenter.rb
@@ -20,6 +20,17 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
     end
   end
 
+  def unmergeable_reasons
+    strong_memoize(:unmergeable_reasons) do
+      reasons = []
+      reasons << "no commits" if merge_request.has_no_commits?
+      reasons << "source branch is missing" unless merge_request.source_branch_exists?
+      reasons << "target branch is missing" unless merge_request.target_branch_exists?
+      reasons << "has merge conflicts" unless merge_request.project.repository.can_be_merged?(merge_request.diff_head_sha, merge_request.target_branch)
+      reasons
+    end
+  end
+
   def cancel_merge_when_pipeline_succeeds_path
     if can_cancel_merge_when_pipeline_succeeds?(current_user)
       cancel_merge_when_pipeline_succeeds_project_merge_request_path(project, merge_request)
diff --git a/app/services/merge_requests/merge_when_pipeline_succeeds_service.rb b/app/services/merge_requests/merge_when_pipeline_succeeds_service.rb
index 850deb0ac7a..9a4e6eb2e88 100644
--- a/app/services/merge_requests/merge_when_pipeline_succeeds_service.rb
+++ b/app/services/merge_requests/merge_when_pipeline_succeeds_service.rb
@@ -24,11 +24,7 @@ module MergeRequests
 
       pipeline_merge_requests(pipeline) do |merge_request|
         next unless merge_request.merge_when_pipeline_succeeds?
-
-        unless merge_request.mergeable?
-          todo_service.merge_request_became_unmergeable(merge_request)
-          next
-        end
+        next unless merge_request.mergeable?
 
         merge_request.merge_async(merge_request.merge_user_id, merge_request.merge_params)
       end
diff --git a/app/services/notification_recipient_service.rb b/app/services/notification_recipient_service.rb
index 5658699664d..4fa38665abc 100644
--- a/app/services/notification_recipient_service.rb
+++ b/app/services/notification_recipient_service.rb
@@ -18,6 +18,10 @@ module NotificationRecipientService
     Builder::NewNote.new(*a).notification_recipients
   end
 
+  def self.build_merge_request_unmergeable_recipients(*a)
+    Builder::MergeRequestUnmergeable.new(*a).notification_recipients
+  end
+
   module Builder
     class Base
       def initialize(*)
@@ -330,5 +334,26 @@ module NotificationRecipientService
         note.author
       end
     end
+
+    class MergeRequestUnmergeable < Base
+      attr_reader :target
+      def initialize(merge_request)
+        @target = merge_request
+      end
+
+      def build!
+        target.merge_participants.each do |user|
+          add_recipients(user, :participating, nil)
+        end
+      end
+
+      def custom_action
+        :unmergeable_merge_request
+      end
+
+      def acting_user
+        nil
+      end
+    end
   end
 end
diff --git a/app/services/notification_service.rb b/app/services/notification_service.rb
index 55a1735e54b..636cfbf5b45 100644
--- a/app/services/notification_service.rb
+++ b/app/services/notification_service.rb
@@ -129,6 +129,7 @@ class NotificationService
 
   # When create a merge request we should send an email to:
   #
+  #  * mr author
   #  * mr assignee if their notification level is not Disabled
   #  * project team members with notification level higher then Participating
   #  * watchers of the mr's labels
@@ -148,6 +149,15 @@ class NotificationService
     end
   end
 
+  # When a merge request is found to be unmergeable, we should send an email to:
+  #
+  #  * mr author
+  #  * mr merge user if set
+  #
+  def merge_request_unmergeable(merge_request)
+    merge_request_unmergeable_email(merge_request)
+  end
+
   # When merge request text is updated, we should send an email to:
   #
   #  * newly mentioned project team members with notification level higher than Participating
@@ -484,6 +494,14 @@ class NotificationService
     end
   end
 
+  def merge_request_unmergeable_email(merge_request)
+    recipients = NotificationRecipientService.build_merge_request_unmergeable_recipients(merge_request)
+
+    recipients.each do |recipient|
+      mailer.merge_request_unmergeable_email(recipient.user.id, merge_request.id).deliver_later
+    end
+  end
+
   def mailer
     Notify
   end
diff --git a/app/services/todo_service.rb b/app/services/todo_service.rb
index ffd48e842c2..f91cd03bf5c 100644
--- a/app/services/todo_service.rb
+++ b/app/services/todo_service.rb
@@ -98,12 +98,12 @@ class TodoService
 
   # When a build fails on the HEAD of a merge request we should:
   #
-  #  * create a todo for author of MR to fix it
-  #  * create a todo for merge_user to keep an eye on it
+  #  * create a todo for each merge participant
   #
   def merge_request_build_failed(merge_request)
-    create_build_failed_todo(merge_request, merge_request.author)
-    create_build_failed_todo(merge_request, merge_request.merge_user) if merge_request.merge_when_pipeline_succeeds?
+    merge_request.merge_participants.each do |user|
+      create_build_failed_todo(merge_request, user)
+    end
   end
 
   # When a new commit is pushed to a merge request we should:
@@ -116,20 +116,22 @@ class TodoService
 
   # When a build is retried to a merge request we should:
   #
-  #  * mark all pending todos related to the merge request for the author as done
-  #  * mark all pending todos related to the merge request for the merge_user as done
+  #  * mark all pending todos related to the merge request as done for each merge participant
   #
   def merge_request_build_retried(merge_request)
-    mark_pending_todos_as_done(merge_request, merge_request.author)
-    mark_pending_todos_as_done(merge_request, merge_request.merge_user) if merge_request.merge_when_pipeline_succeeds?
+    merge_request.merge_participants.each do |user|
+      mark_pending_todos_as_done(merge_request, user)
+    end
   end
 
-  # When a merge request could not be automatically merged due to its unmergeable state we should:
+  # When a merge request could not be merged due to its unmergeable state we should:
   #
-  #  * create a todo for a merge_user
+  #  * create a todo for each merge participant
   #
   def merge_request_became_unmergeable(merge_request)
-    create_unmergeable_todo(merge_request, merge_request.merge_user) if merge_request.merge_when_pipeline_succeeds?
+    merge_request.merge_participants.each do |user|
+      create_unmergeable_todo(merge_request, user)
+    end
   end
 
   # When create a note we should:
@@ -275,9 +277,9 @@ class TodoService
     create_todos(todo_author, attributes)
   end
 
-  def create_unmergeable_todo(merge_request, merge_user)
-    attributes = attributes_for_todo(merge_request.project, merge_request, merge_user, Todo::UNMERGEABLE)
-    create_todos(merge_user, attributes)
+  def create_unmergeable_todo(merge_request, todo_author)
+    attributes = attributes_for_todo(merge_request.project, merge_request, todo_author, Todo::UNMERGEABLE)
+    create_todos(todo_author, attributes)
   end
 
   def attributes_for_target(target)
diff --git a/app/views/notify/merge_request_unmergeable_email.html.haml b/app/views/notify/merge_request_unmergeable_email.html.haml
new file mode 100644
index 00000000000..e84905a5fad
--- /dev/null
+++ b/app/views/notify/merge_request_unmergeable_email.html.haml
@@ -0,0 +1,6 @@
+%p
+  Merge Request #{link_to @merge_request.to_reference, project_merge_request_url(@merge_request.target_project, @merge_request)} can no longer be merged due to the following #{pluralize(@reasons, 'reason')}:
+
+  %ul
+    - @reasons.each do |reason|
+      %li= reason
diff --git a/app/views/notify/merge_request_unmergeable_email.text.haml b/app/views/notify/merge_request_unmergeable_email.text.haml
new file mode 100644
index 00000000000..4f0901c761a
--- /dev/null
+++ b/app/views/notify/merge_request_unmergeable_email.text.haml
@@ -0,0 +1,11 @@
+Merge Request #{@merge_request.to_reference} can no longer be merged due to the following #{pluralize(@reasons, 'reason')}:
+
+- @reasons.each do |reason|
+  * #{reason}
+
+Merge Request url: #{project_merge_request_url(@merge_request.target_project, @merge_request)}
+
+= merge_path_description(@merge_request, 'to')
+
+Author: #{@merge_request.author_name}
+Assignee: #{@merge_request.assignee_name}