public function get_chart_legend() {

		if ( empty( $this->product_ids ) ) {
			return array();
		}

		$legend = array();

		$total_sales = $this->get_order_report_data(
			array(
				'data'         => array(
					'_line_total' => array(
						'type'            => 'order_item_meta',
						'order_item_type' => 'line_item',
						'function'        => 'SUM',
						'name'            => 'order_item_amount',
					),
				),
				'where_meta'   => array(
					'relation' => 'OR',
					array(
						'type'       => 'order_item_meta',
						'meta_key'   => array( '_product_id', '_variation_id' ), // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
						'meta_value' => $this->product_ids, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value
						'operator'   => 'IN',
					),
				),
				'query_type'   => 'get_var',
				'filter_range' => true,
				'order_status' => array( 'completed', 'processing', 'on-hold', 'refunded' ),
			)
		);

		$total_items = absint(
			$this->get_order_report_data(
				array(
					'data'         => array(
						'_qty' => array(
							'type'            => 'order_item_meta',
							'order_item_type' => 'line_item',
							'function'        => 'SUM',
							'name'            => 'order_item_count',
						),
					),
					'where_meta'   => array(
						'relation' => 'OR',
						array(
							'type'       => 'order_item_meta',
							'meta_key'   => array( '_product_id', '_variation_id' ), // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
							'meta_value' => $this->product_ids, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value
							'operator'   => 'IN',
						),
					),
					'query_type'   => 'get_var',
					'filter_range' => true,
					'order_status' => array( 'completed', 'processing', 'on-hold', 'refunded' ),
				)
			)
		);

		$legend[] = array(
			/* translators: %s: total items sold */
			'title'            => sprintf( __( '%s sales for the selected items', 'woocommerce' ), '<strong>' . wc_price( $total_sales ) . '</strong>' ),
			'color'            => $this->chart_colours['sales_amount'],
			'highlight_series' => 1,
		);

		$legend[] = array(
			/* translators: %s: total items purchased */
			'title'            => sprintf( __( '%s purchases for the selected items', 'woocommerce' ), '<strong>' . ( $total_items ) . '</strong>' ),
			'color'            => $this->chart_colours['item_count'],
			'highlight_series' => 0,
		);

		return $legend;
	}