1 files changed, 52 insertions, 0 deletions
diff --git a/app/services/work_items/task_list_reference_replacement_service.rb b/app/services/work_items/task_list_reference_replacement_service.rb
new file mode 100644
index 00000000000..1044a4feb88
--- /dev/null
+++ b/app/services/work_items/task_list_reference_replacement_service.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module WorkItems
+  class TaskListReferenceReplacementService
+    STALE_OBJECT_MESSAGE = 'Stale work item. Check lock version'
+
+    def initialize(work_item:, work_item_reference:, line_number_start:, line_number_end:, title:, lock_version:)
+      @work_item = work_item
+      @work_item_reference = work_item_reference
+      @line_number_start = line_number_start
+      @line_number_end = line_number_end
+      @title = title
+      @lock_version = lock_version
+    end
+
+    def execute
+      return ::ServiceResponse.error(message: STALE_OBJECT_MESSAGE) if @work_item.lock_version > @lock_version
+      return ::ServiceResponse.error(message: 'line_number_start must be greater than 0') if @line_number_start < 1
+      return ::ServiceResponse.error(message: 'line_number_end must be greater or equal to line_number_start') if @line_number_end < @line_number_start
+      return ::ServiceResponse.error(message: "Work item description can't be blank") if @work_item.description.blank?
+
+      source_lines = @work_item.description.split("\n")
+      markdown_task_first_line = source_lines[@line_number_start - 1]
+      task_line = Taskable::ITEM_PATTERN.match(markdown_task_first_line)
+
+      return ::ServiceResponse.error(message: "Unable to detect a task on line #{@line_number_start}") unless task_line
+
+      captures = task_line.captures
+
+      markdown_task_first_line.sub!(Taskable::ITEM_PATTERN, "#{captures[0]} #{captures[1]} #{@work_item_reference}+")
+
+      source_lines[@line_number_start - 1] = markdown_task_first_line
+      remove_additional_lines!(source_lines)
+
+      @work_item.update!(description: source_lines.join("\n"))
+
+      ::ServiceResponse.success
+    rescue ActiveRecord::StaleObjectError
+      ::ServiceResponse.error(message: STALE_OBJECT_MESSAGE)
+    end
+
+    private
+
+    def remove_additional_lines!(source_lines)
+      return if @line_number_end <= @line_number_start
+
+      source_lines.delete_if.each_with_index do |_line, index|
+        index >= @line_number_start && index < @line_number_end
+      end
+    end
+  end
+end