/**
 * Monthly Sales Custom Shortcode
 */
add_shortcode( 'display_monthly_sales', 'print_monthly_sales_frontend' );

function print_monthly_sales_frontend() {
    global $woocommerce, $wpdb, $product;
    include_once($woocommerce->plugin_path() . '/includes/admin/reports/class-wc-admin-report.php');

    // WooCommerce Admin Report
    $wc_report = new WC_Admin_Report();

    // Set date parameters for the current month
    $start_date = strtotime(date('Y-m', current_time('timestamp')) . '-01 midnight');
    $end_date = strtotime('+1month', $start_date) - 86400;
    $wc_report->start_date = $start_date;
    $wc_report->end_date = $end_date;

    // Avoid max join size error
    $wpdb->query('SET SQL_BIG_SELECTS=1');

  	$last_month = (array) $wc_report->get_order_report_data(
			array(
				'data'         => array(
					'_order_total'        => array(
						'type'     => 'meta',
						'function' => 'SUM',
						'name'     => 'total_sales',
					),
				),
				'group_by'     => $wc_report->group_by_query,
				'order_by'     => 'post_date ASC',
				'query_type'   => 'get_results',
				'filter_range' => 'month',
				'order_types'  => wc_get_order_types( 'sales-reports' ),
				'order_status' => array( 'completed', 'processing', 'on-hold', 'refunded' ),
			)
		);

        ?>
        <div class="total-sales">
		<h1><?php echo get_woocommerce_currency_symbol() . intval($last_month[0]->total_sales); ?></h1>
		<p>Last 30 days in sales</p>
        </div>
        <?php
}