public function get_main_chart() {
		global $wp_locale;

		// Get orders and dates in range - we want the SUM of order totals, COUNT of order items, COUNT of orders, and the date.
		$order_coupon_counts_query = array(
			'data'         => array(
				'order_item_name' => array(
					'type'            => 'order_item',
					'order_item_type' => 'coupon',
					'function'        => 'COUNT',
					'name'            => 'order_coupon_count',
				),
				'post_date'       => array(
					'type'     => 'post_data',
					'function' => '',
					'name'     => 'post_date',
				),
			),
			'where'        => array(
				array(
					'key'      => 'order_item_type',
					'value'    => 'coupon',
					'operator' => '=',
				),
			),
			'group_by'     => $this->group_by_query,
			'order_by'     => 'post_date ASC',
			'query_type'   => 'get_results',
			'filter_range' => true,
			'order_types'  => wc_get_order_types( 'order-count' ),
		);

		$order_discount_amounts_query = array(
			'data'         => array(
				'discount_amount' => array(
					'type'            => 'order_item_meta',
					'order_item_type' => 'coupon',
					'function'        => 'SUM',
					'name'            => 'discount_amount',
				),
				'post_date'       => array(
					'type'     => 'post_data',
					'function' => '',
					'name'     => 'post_date',
				),
			),
			'where'        => array(
				array(
					'key'      => 'order_item_type',
					'value'    => 'coupon',
					'operator' => '=',
				),
			),
			'group_by'     => $this->group_by_query . ', order_item_name',
			'order_by'     => 'post_date ASC',
			'query_type'   => 'get_results',
			'filter_range' => true,
			'order_types'  => wc_get_order_types( 'order-count' ),
		);

		if ( ! empty( $this->coupon_codes ) ) {
			$coupon_code_query = array(
				'type'     => 'order_item',
				'key'      => 'order_item_name',
				'value'    => $this->coupon_codes,
				'operator' => 'IN',
			);

			$order_coupon_counts_query['where'][]    = $coupon_code_query;
			$order_discount_amounts_query['where'][] = $coupon_code_query;
		}

		$order_coupon_counts    = $this->get_order_report_data( $order_coupon_counts_query );
		$order_discount_amounts = $this->get_order_report_data( $order_discount_amounts_query );

		// Prepare data for report.
		$order_coupon_counts    = $this->prepare_chart_data( $order_coupon_counts, 'post_date', 'order_coupon_count', $this->chart_interval, $this->start_date, $this->chart_groupby );
		$order_discount_amounts = $this->prepare_chart_data( $order_discount_amounts, 'post_date', 'discount_amount', $this->chart_interval, $this->start_date, $this->chart_groupby );

		// Encode in json format.
		$chart_data = wp_json_encode(
			array(
				'order_coupon_counts'    => array_values( $order_coupon_counts ),
				'order_discount_amounts' => array_values( $order_discount_amounts ),
			)
		);
		?>
		<div class="chart-container">
			<div class="chart-placeholder main"></div>
		</div>
		<script type="text/javascript">
			var main_chart;

			jQuery(function(){
				var order_data = JSON.parse( decodeURIComponent( '<?php echo rawurlencode( $chart_data ); ?>' ) );

				var drawGraph = function( highlight ) {
					var series = [
						{
							label: "<?php echo esc_js( __( 'Number of coupons used', 'woocommerce' ) ); ?>",
							data: order_data.order_coupon_counts,
							color: '<?php echo esc_js( $this->chart_colours['coupon_count'] ); ?>',
							bars: { fillColor: '<?php echo esc_js( $this->chart_colours['coupon_count'] ); ?>', fill: true, show: true, lineWidth: 0, barWidth: <?php echo esc_js( $this->barwidth ); ?> * 0.5, align: 'center' },
							shadowSize: 0,
							hoverable: false
						},
						{
							label: "<?php echo esc_js( __( 'Discount amount', 'woocommerce' ) ); ?>",
							data: order_data.order_discount_amounts,
							yaxis: 2,
							color: '<?php echo esc_js( $this->chart_colours['discount_amount'] ); ?>',
							points: { show: true, radius: 5, lineWidth: 3, fillColor: '#fff', fill: true },
							lines: { show: true, lineWidth: 4, fill: false },
							shadowSize: 0,
							<?php echo $this->get_currency_tooltip(); ?><?php // @codingStandardsIgnoreLine ?>
						}
					];

					if ( highlight !== 'undefined' && series[ highlight ] ) {
						highlight_series = series[ highlight ];

						highlight_series.color = '#9c5d90';

						if ( highlight_series.bars )
							highlight_series.bars.fillColor = '#9c5d90';

						if ( highlight_series.lines ) {
							highlight_series.lines.lineWidth = 5;
						}
					}

					main_chart = jQuery.plot(
						jQuery('.chart-placeholder.main'),
						series,
						{
							legend: {
								show: false
							},
							grid: {
								color: '#aaa',
								borderColor: 'transparent',
								borderWidth: 0,
								hoverable: true
							},
							xaxes: [ {
								color: '#aaa',
								position: "bottom",
								tickColor: 'transparent',
								mode: "time",
								timeformat: "<?php echo ( 'day' === $this->chart_groupby ) ? '%d %b' : '%b'; ?>",
								monthNames: JSON.parse( decodeURIComponent( '<?php echo rawurlencode( wp_json_encode( array_values( $wp_locale->month_abbrev ) ) ); ?>' ) ),
								tickLength: 1,
								minTickSize: [1, "<?php echo esc_js( $this->chart_groupby ); ?>"],
								font: {
									color: "#aaa"
								}
							} ],
							yaxes: [
								{
									min: 0,
									minTickSize: 1,
									tickDecimals: 0,
									color: '#ecf0f1',
									font: { color: "#aaa" }
								},
								{
									position: "right",
									min: 0,
									tickDecimals: 2,
									alignTicksWithAxis: 1,
									color: 'transparent',
									font: { color: "#aaa" }
								}
							],
						}
					);

					jQuery('.chart-placeholder').resize();
				}

				drawGraph();

				jQuery('.highlight_series').hover(
					function() {
						drawGraph( jQuery(this).data('series') );
					},
					function() {
						drawGraph();
					}
				);
			});
		</script>
		<?php
	}