Delegate a single discussion to a new issue

Delegate a discussion in a merge request into a new issue.
The discussion wil be marked as resolved and a system note will be
added linking to the newly created issue.

3 files changed, 46 insertions, 17 deletions

diff --git a/app/services/issues/base_service.rb b/app/services/issues/base_service.rb
index 35af867a098..3aa842eb9a8 100644
--- a/app/services/issues/base_service.rb
+++ b/app/services/issues/base_service.rb
@@ -1,11 +1,12 @@
 module Issues
   class BaseService < ::IssuableBaseService
-    attr_reader :merge_request_for_resolving_discussions
+    attr_reader :merge_request_for_resolving_discussions, :discussion_to_resolve
 
     def initialize(*args)
       super
 
       @merge_request_for_resolving_discussions ||= params.delete(:merge_request_for_resolving_discussions)
+      @discussion_to_resolve ||= params.delete(:discussion_to_resolve)
     end
 
     def hook_data(issue, action)
@@ -15,6 +16,28 @@ module Issues
       issue_data
     end
 
+    def merge_request_for_resolving_discussions
+      @merge_request_for_resolving_discussions ||= discussion_to_resolve.try(:noteable)
+    end
+
+    def for_all_discussions_in_a_merge_request?
+      discussion_to_resolve.nil? && merge_request_for_resolving_discussions
+    end
+
+    def for_single_discussion?
+      discussion_to_resolve && discussion_to_resolve.noteable == merge_request_for_resolving_discussions
+    end
+
+    def discussions_to_resolve
+      @discussions_to_resolve ||= if for_all_discussions_in_a_merge_request?
+                                    merge_request_for_resolving_discussions.resolvable_discussions
+                                  elsif for_single_discussion?
+                                    Array(discussion_to_resolve)
+                                  else
+                                    []
+                                  end
+    end
+
     private
 
     def execute_hooks(issue, action = 'open')
diff --git a/app/services/issues/build_service.rb b/app/services/issues/build_service.rb
index 7cd927d8005..1bcc5abd3f2 100644
--- a/app/services/issues/build_service.rb
+++ b/app/services/issues/build_service.rb
@@ -4,32 +4,35 @@ module Issues
       @issue = project.issues.new(issue_params)
     end
 
-    def issue_params_with_info_from_merge_request
+    def issue_params_with_info_from_discussions
       return {} unless merge_request_for_resolving_discussions
 
-      { title: title_from_merge_request, description: description_from_merge_request }
+      { title: title_for_merge_request, description: description_for_discussions }
     end
 
-    def title_from_merge_request
+    def title_for_merge_request
       "Follow-up from \"#{merge_request_for_resolving_discussions.title}\""
     end
 
-    def description_from_merge_request
-      if merge_request_for_resolving_discussions.resolvable_discussions.empty?
+    def description_for_discussions
+      if discussions_to_resolve.empty?
         return "There are no unresolved discussions. "\
                "Review the conversation in #{merge_request_for_resolving_discussions.to_reference}"
       end
 
-      description = "The following discussions from #{merge_request_for_resolving_discussions.to_reference} should be addressed:"
+      description = "The following #{'discussion'.pluralize(discussions_to_resolve.size)} "\
+                    "from #{merge_request_for_resolving_discussions.to_reference} "\
+                    "should be addressed:"
+
       [description, *items_for_discussions].join("\n\n")
     end
 
     def items_for_discussions
-      merge_request_for_resolving_discussions.resolvable_discussions.map { |discussion| item_for_discussion(discussion) }
+      discussions_to_resolve.map { |discussion| item_for_discussion(discussion) }
     end
 
     def item_for_discussion(discussion)
-      first_note = discussion.first_note_to_resolve
+      first_note = discussion.first_note_to_resolve || discussion.first_note
       other_note_count = discussion.notes.size - 1
       creation_time = first_note.created_at.to_s(:medium)
       note_url = Gitlab::UrlBuilder.build(first_note)
@@ -44,7 +47,7 @@ module Issues
     end
 
     def issue_params
-      @issue_params ||= issue_params_with_info_from_merge_request.merge(whitelisted_issue_params)
+      @issue_params ||= issue_params_with_info_from_discussions.merge(whitelisted_issue_params)
     end
 
     def whitelisted_issue_params
diff --git a/app/services/issues/create_service.rb b/app/services/issues/create_service.rb
index 85b6eb3fe3d..d2cc70ed0dc 100644
--- a/app/services/issues/create_service.rb
+++ b/app/services/issues/create_service.rb
@@ -5,7 +5,11 @@ module Issues
     def execute
       filter_spam_check_params
 
-      issue_attributes = params.merge(merge_request_for_resolving_discussions: merge_request_for_resolving_discussions)
+      issue_attributes = params.merge(
+        merge_request_for_resolving_discussions: merge_request_for_resolving_discussions,
+        discussion_to_resolve: discussion_to_resolve
+      )
+
       @issue = BuildService.new(project, current_user, issue_attributes).execute
 
       create(@issue)
@@ -21,17 +25,16 @@ module Issues
       notification_service.new_issue(issuable, current_user)
       todo_service.new_issue(issuable, current_user)
       user_agent_detail_service.create
-
-      if merge_request_for_resolving_discussions.try(:discussions_can_be_resolved_by?, current_user)
-        resolve_discussions_in_merge_request(issuable)
-      end
+      resolve_discussions_with_issue(issuable)
     end
 
-    def resolve_discussions_in_merge_request(issue)
+    def resolve_discussions_with_issue(issue)
+      return if discussions_to_resolve.empty?
+
       Discussions::ResolveService.new(project, current_user,
                                       merge_request: merge_request_for_resolving_discussions,
                                       follow_up_issue: issue).
-          execute(merge_request_for_resolving_discussions.resolvable_discussions)
+          execute(discussions_to_resolve)
     end
 
     private