private function setup_report( $filter ) {

		include_once( WC()->plugin_path() . '/includes/admin/reports/class-wc-admin-report.php' );
		include_once( WC()->plugin_path() . '/includes/admin/reports/class-wc-report-sales-by-date.php' );

		$this->report = new WC_Report_Sales_By_Date();

		if ( empty( $filter['period'] ) ) {

			// custom date range
			$filter['period'] = 'custom';

			if ( ! empty( $filter['date_min'] ) || ! empty( $filter['date_max'] ) ) {

				// overwrite _GET to make use of WC_Admin_Report::calculate_current_range() for custom date ranges
				$_GET['start_date'] = $this->server->parse_datetime( $filter['date_min'] );
				$_GET['end_date'] = isset( $filter['date_max'] ) ? $this->server->parse_datetime( $filter['date_max'] ) : null;

			} else {

				// default custom range to today
				$_GET['start_date'] = $_GET['end_date'] = date( 'Y-m-d', current_time( 'timestamp' ) );
			}
		} else {

			// ensure period is valid
			if ( ! in_array( $filter['period'], array( 'week', 'month', 'last_month', 'year' ) ) ) {
				$filter['period'] = 'week';
			}

			// TODO: change WC_Admin_Report class to use "week" instead, as it's more consistent with other periods
			// allow "week" for period instead of "7day"
			if ( 'week' === $filter['period'] ) {
				$filter['period'] = '7day';
			}
		}

		$this->report->calculate_current_range( $filter['period'] );
	}