1 files changed, 84 insertions, 0 deletions
diff --git a/app/services/design_management/move_designs_service.rb b/app/services/design_management/move_designs_service.rb
new file mode 100644
index 00000000000..de763caba2f
--- /dev/null
+++ b/app/services/design_management/move_designs_service.rb
@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+module DesignManagement
+  class MoveDesignsService < DesignService
+    # @param user [User] The current user
+    # @param [Hash] params
+    # @option params [DesignManagement::Design] :current_design
+    # @option params [DesignManagement::Design] :previous_design (nil)
+    # @option params [DesignManagement::Design] :next_design (nil)
+    def initialize(user, params)
+      super(nil, user, params.merge(issue: nil))
+    end
+
+    def execute
+      return error(:no_focus) unless current_design.present?
+      return error(:cannot_move) unless ::Feature.enabled?(:reorder_designs, project, default_enabled: true)
+      return error(:cannot_move) unless current_user.can?(:move_design, current_design)
+      return error(:no_neighbors) unless neighbors.present?
+      return error(:not_distinct) unless all_distinct?
+      return error(:not_adjacent) if any_in_gap?
+      return error(:not_same_issue) unless all_same_issue?
+
+      move_nulls_to_end
+      current_design.move_between(previous_design, next_design)
+      current_design.save!
+      success
+    end
+
+    def error(message)
+      ServiceResponse.error(message: message)
+    end
+
+    def success
+      ServiceResponse.success
+    end
+
+    private
+
+    delegate :issue, :project, to: :current_design
+
+    def move_nulls_to_end
+      moved_records = current_design.class.move_nulls_to_end(issue.designs.in_creation_order)
+      return if moved_records == 0
+
+      current_design.reset
+      next_design&.reset
+      previous_design&.reset
+    end
+
+    def neighbors
+      [previous_design, next_design].compact
+    end
+
+    def all_distinct?
+      ids.uniq.size == ids.size
+    end
+
+    def any_in_gap?
+      return false unless previous_design&.relative_position && next_design&.relative_position
+
+      !previous_design.immediately_before?(next_design)
+    end
+
+    def all_same_issue?
+      issue.designs.id_in(ids).count == ids.size
+    end
+
+    def ids
+      @ids ||= [current_design, *neighbors].map(&:id)
+    end
+
+    def current_design
+      params[:current_design]
+    end
+
+    def previous_design
+      params[:previous_design]
+    end
+
+    def next_design
+      params[:next_design]
+    end
+  end
+end