public function get_sales_report( $fields = null, $filter = array() ) {

		// check user permissions
		$check = $this->validate_request();

		// check for WP_Error
		if ( is_wp_error( $check ) ) {
			return $check;
		}

		// set date filtering
		$this->setup_report( $filter );

		// new customers
		$users_query = new WP_User_Query(
			array(
				'fields' => array( 'user_registered' ),
				'role'   => 'customer',
			)
		);

		$customers = $users_query->get_results();

		foreach ( $customers as $key => $customer ) {
			if ( strtotime( $customer->user_registered ) < $this->report->start_date || strtotime( $customer->user_registered ) > $this->report->end_date ) {
				unset( $customers[ $key ] );
			}
		}

		$total_customers = count( $customers );
		$report_data     = $this->report->get_report_data();
		$period_totals   = array();

		// setup period totals by ensuring each period in the interval has data
		for ( $i = 0; $i <= $this->report->chart_interval; $i ++ ) {

			switch ( $this->report->chart_groupby ) {
				case 'day' :
					$time = date( 'Y-m-d', strtotime( "+{$i} DAY", $this->report->start_date ) );
					break;
				default :
					$time = date( 'Y-m', strtotime( "+{$i} MONTH", $this->report->start_date ) );
					break;
			}

			// set the customer signups for each period
			$customer_count = 0;
			foreach ( $customers as $customer ) {
				if ( date( ( 'day' == $this->report->chart_groupby ) ? 'Y-m-d' : 'Y-m', strtotime( $customer->user_registered ) ) == $time ) {
					$customer_count++;
				}
 			}

			$period_totals[ $time ] = array(
				'sales'     => wc_format_decimal( 0.00, 2 ),
				'orders'    => 0,
				'items'     => 0,
				'tax'       => wc_format_decimal( 0.00, 2 ),
				'shipping'  => wc_format_decimal( 0.00, 2 ),
				'discount'  => wc_format_decimal( 0.00, 2 ),
				'customers' => $customer_count,
			);
		}

		// add total sales, total order count, total tax and total shipping for each period
		foreach ( $report_data->orders as $order ) {
			$time = ( 'day' === $this->report->chart_groupby ) ? date( 'Y-m-d', strtotime( $order->post_date ) ) : date( 'Y-m', strtotime( $order->post_date ) );

			if ( ! isset( $period_totals[ $time ] ) ) {
				continue;
			}

			$period_totals[ $time ]['sales']    = wc_format_decimal( $order->total_sales, 2 );
			$period_totals[ $time ]['tax']      = wc_format_decimal( $order->total_tax + $order->total_shipping_tax, 2 );
			$period_totals[ $time ]['shipping'] = wc_format_decimal( $order->total_shipping, 2 );
		}

		foreach ( $report_data->order_counts as $order ) {
			$time = ( 'day' === $this->report->chart_groupby ) ? date( 'Y-m-d', strtotime( $order->post_date ) ) : date( 'Y-m', strtotime( $order->post_date ) );

			if ( ! isset( $period_totals[ $time ] ) ) {
				continue;
			}

			$period_totals[ $time ]['orders']   = (int) $order->count;
		}

		// add total order items for each period
		foreach ( $report_data->order_items as $order_item ) {
			$time = ( 'day' === $this->report->chart_groupby ) ? date( 'Y-m-d', strtotime( $order_item->post_date ) ) : date( 'Y-m', strtotime( $order_item->post_date ) );

			if ( ! isset( $period_totals[ $time ] ) ) {
				continue;
			}

			$period_totals[ $time ]['items'] = (int) $order_item->order_item_count;
		}

		// add total discount for each period
		foreach ( $report_data->coupons as $discount ) {
			$time = ( 'day' === $this->report->chart_groupby ) ? date( 'Y-m-d', strtotime( $discount->post_date ) ) : date( 'Y-m', strtotime( $discount->post_date ) );

			if ( ! isset( $period_totals[ $time ] ) ) {
				continue;
			}

			$period_totals[ $time ]['discount'] = wc_format_decimal( $discount->discount_amount, 2 );
		}

		$sales_data  = array(
			'total_sales'       => $report_data->total_sales,
			'net_sales'         => $report_data->net_sales,
			'average_sales'     => $report_data->average_sales,
			'total_orders'      => $report_data->total_orders,
			'total_items'       => $report_data->total_items,
			'total_tax'         => wc_format_decimal( $report_data->total_tax + $report_data->total_shipping_tax, 2 ),
			'total_shipping'    => $report_data->total_shipping,
			'total_refunds'     => $report_data->total_refunds,
			'total_discount'    => $report_data->total_coupons,
			'totals_grouped_by' => $this->report->chart_groupby,
			'totals'            => $period_totals,
			'total_customers'   => $total_customers,
		);

		return array( 'sales' => apply_filters( 'woocommerce_api_report_response', $sales_data, $this->report, $fields, $this->server ) );
	}