1 files changed, 128 insertions, 0 deletions
diff --git a/app/services/boards/base_items_list_service.rb b/app/services/boards/base_items_list_service.rb
new file mode 100644
index 00000000000..851120ef597
--- /dev/null
+++ b/app/services/boards/base_items_list_service.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+module Boards
+  class BaseItemsListService < Boards::BaseService
+    include Gitlab::Utils::StrongMemoize
+    include ActiveRecord::ConnectionAdapters::Quoting
+
+    def execute
+      return items.order_closed_date_desc if list&.closed?
+
+      ordered_items
+    end
+
+    private
+
+    def ordered_items
+      raise NotImplementedError
+    end
+
+    def finder
+      raise NotImplementedError
+    end
+
+    def board
+      raise NotImplementedError
+    end
+
+    def item_model
+      raise NotImplementedError
+    end
+
+    # We memoize the query here since the finder methods we use are quite complex. This does not memoize the result of the query.
+    # rubocop: disable CodeReuse/ActiveRecord
+    def items
+      strong_memoize(:items) do
+        filter(finder.execute).reorder(nil)
+      end
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+
+    def filter(items)
+      # when grouping board issues by epics (used in board swimlanes)
+      # we need to get all issues in the board
+      # TODO: ignore hidden columns -
+      # https://gitlab.com/gitlab-org/gitlab/-/issues/233870
+      return items if params[:all_lists]
+
+      items = without_board_labels(items) unless list&.movable? || list&.closed?
+      items = with_list_label(items) if list&.label?
+      items
+    end
+
+    def list
+      return unless params.key?(:id)
+
+      strong_memoize(:list) do
+        id = params[:id]
+
+        if board.lists.loaded?
+          board.lists.find { |l| l.id == id }
+        else
+          board.lists.find(id)
+        end
+      end
+    end
+
+    def filter_params
+      set_parent
+      set_state
+      set_attempt_search_optimizations
+
+      params
+    end
+
+    def set_parent
+      if parent.is_a?(Group)
+        params[:group_id] = parent.id
+      else
+        params[:project_id] = parent.id
+      end
+    end
+
+    def set_state
+      return if params[:all_lists]
+
+      params[:state] = list && list.closed? ? 'closed' : 'opened'
+    end
+
+    def set_attempt_search_optimizations
+      return unless params[:search].present?
+
+      if board.group_board?
+        params[:attempt_group_search_optimizations] = true
+      else
+        params[:attempt_project_search_optimizations] = true
+      end
+    end
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def board_label_ids
+      @board_label_ids ||= board.lists.movable.pluck(:label_id)
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def without_board_labels(items)
+      return items unless board_label_ids.any?
+
+      items.where.not('EXISTS (?)', label_links(board_label_ids).limit(1))
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def label_links(label_ids)
+      LabelLink
+        .where('label_links.target_type = ?', item_model)
+        .where(item_model.arel_table[:id].eq(LabelLink.arel_table[:target_id]).to_sql)
+        .where(label_id: label_ids)
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def with_list_label(items)
+      items.where('EXISTS (?)', label_links(list.label_id).limit(1))
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+  end
+end