7 files changed, 110 insertions, 3 deletions
diff --git a/app/services/discussions/base_service.rb b/app/services/discussions/base_service.rb
new file mode 100644
index 00000000000..e4dfe6e71bb
--- /dev/null
+++ b/app/services/discussions/base_service.rb
@@ -0,0 +1,4 @@
+module Discussions
+  class BaseService < ::BaseService
+  end
+end
diff --git a/app/services/discussions/resolve_service.rb b/app/services/discussions/resolve_service.rb
new file mode 100644
index 00000000000..0437195f588
--- /dev/null
+++ b/app/services/discussions/resolve_service.rb
@@ -0,0 +1,24 @@
+module Discussions
+  class ResolveService < Discussions::BaseService
+    def execute(one_or_more_discussions)
+      Array(one_or_more_discussions).each { |discussion| resolve_discussion(discussion) }
+    end
+
+    def resolve_discussion(discussion)
+      return unless discussion.can_resolve?(current_user)
+
+      discussion.resolve!(current_user)
+
+      MergeRequests::ResolvedDiscussionNotificationService.new(project, current_user).execute(merge_request)
+      SystemNoteService.discussion_continued_in_issue(discussion, project, current_user, follow_up_issue) if follow_up_issue
+    end
+
+    def merge_request
+      params[:merge_request]
+    end
+
+    def follow_up_issue
+      params[:follow_up_issue]
+    end
+  end
+end
diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index ce68e433ab8..b5f63cc5a1a 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -120,9 +120,10 @@ class IssuableBaseService < BaseService
   def merge_slash_commands_into_params!(issuable)
     description, command_params =
       SlashCommands::InterpretService.new(project, current_user).
-      execute(params[:description], issuable)
+        execute(params[:description], issuable)
 
-    params[:description] = description
+    # Avoid a description already set on an issuable to be overwritten by a nil
+    params[:description] = description if params.has_key?(:description)
 
     params.merge!(command_params)
   end
diff --git a/app/services/issues/base_service.rb b/app/services/issues/base_service.rb
index 9ea3ce084ba..742e834df97 100644
--- a/app/services/issues/base_service.rb
+++ b/app/services/issues/base_service.rb
@@ -1,5 +1,13 @@
 module Issues
   class BaseService < ::IssuableBaseService
+    attr_reader :merge_request_for_resolving_discussions
+
+    def initialize(*args)
+      super
+
+      @merge_request_for_resolving_discussions ||= params.delete(:merge_request_for_resolving_discussions)
+    end
+
     def hook_data(issue, action)
       issue_data = issue.to_hook_data(current_user)
       issue_url = Gitlab::UrlBuilder.build(issue)
diff --git a/app/services/issues/build_service.rb b/app/services/issues/build_service.rb
new file mode 100644
index 00000000000..a63982f60c8
--- /dev/null
+++ b/app/services/issues/build_service.rb
@@ -0,0 +1,50 @@
+module Issues
+  class BuildService < Issues::BaseService
+    def execute
+      @issue = project.issues.new(issue_params)
+    end
+
+    def issue_params_with_info_from_merge_request
+      return {} unless merge_request_for_resolving_discussions
+
+      { title: title_from_merge_request, description: description_from_merge_request }
+    end
+
+    def title_from_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?
+        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, *items_for_discussions].join("\n\n")
+    end
+
+    def items_for_discussions
+      merge_request_for_resolving_discussions.resolvable_discussions.map { |discussion| item_for_discussion(discussion) }
+    end
+
+    def item_for_discussion(discussion)
+      first_note = discussion.first_note_to_resolve
+      other_note_count = discussion.notes.size - 1
+      creation_time = first_note.created_at.to_s(:medium)
+      note_url = Gitlab::UrlBuilder.build(first_note)
+
+      discussion_info = "- [ ] #{first_note.author.to_reference} commented in a discussion on [#{creation_time}](#{note_url}): "
+      discussion_info << " (+#{other_note_count} #{'comment'.pluralize(other_note_count)})" if other_note_count > 0
+
+      note_without_block_quotes = Banzai::Filter::BlockquoteFenceFilter.new(first_note.note).call
+      quote = ">>>\n#{note_without_block_quotes}\n>>>"
+
+      [discussion_info, quote].join("\n\n")
+    end
+
+    def issue_params
+      @issue_params ||= issue_params_with_info_from_merge_request.merge(params.slice(:title, :description))
+    end
+  end
+end
diff --git a/app/services/issues/create_service.rb b/app/services/issues/create_service.rb
index ea1690f3e38..d2eb46ac41b 100644
--- a/app/services/issues/create_service.rb
+++ b/app/services/issues/create_service.rb
@@ -4,7 +4,8 @@ module Issues
       @request = params.delete(:request)
       @api = params.delete(:api)
 
-      @issue = project.issues.new
+      issue_attributes = params.merge(merge_request_for_resolving_discussions: merge_request_for_resolving_discussions)
+      @issue = BuildService.new(project, current_user, issue_attributes).execute
 
       create(@issue)
     end
@@ -18,6 +19,17 @@ 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
+    end
+
+    def resolve_discussions_in_merge_request(issue)
+      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)
     end
 
     private
diff --git a/app/services/system_note_service.rb b/app/services/system_note_service.rb
index 3cf6467804f..8b48d90f60b 100644
--- a/app/services/system_note_service.rb
+++ b/app/services/system_note_service.rb
@@ -163,6 +163,14 @@ module SystemNoteService
     create_note(noteable: merge_request, project: project, author: author, note: body)
   end
 
+  def discussion_continued_in_issue(discussion, project, author, issue)
+    body = "Added #{issue.to_reference} to continue this discussion"
+    note_attributes = discussion.reply_attributes.merge(project: project, author: author, note: body)
+    note_attributes[:type] = note_attributes.delete(:note_type)
+
+    create_note(note_attributes)
+  end
+
   # Called when the title of a Noteable is changed
   #
   # noteable  - Noteable object that responds to `title`