public static function pay_action() {
		global $wp;

		if ( isset( $_POST['woocommerce_pay'], $_GET['key'] ) ) {
			wc_nocache_headers();

			$nonce_value = wc_get_var( $_REQUEST['woocommerce-pay-nonce'], wc_get_var( $_REQUEST['_wpnonce'], '' ) ); // @codingStandardsIgnoreLine.

			if ( ! wp_verify_nonce( $nonce_value, 'woocommerce-pay' ) ) {
				return;
			}

			ob_start();

			// Pay for existing order.
			$order_key = wp_unslash( $_GET['key'] ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
			$order_id  = absint( $wp->query_vars['order-pay'] );
			$order     = wc_get_order( $order_id );

			if ( $order_id === $order->get_id() && hash_equals( $order->get_order_key(), $order_key ) && $order->needs_payment() ) {

				do_action( 'woocommerce_before_pay_action', $order );

				WC()->customer->set_props(
					array(
						'billing_country'  => $order->get_billing_country() ? $order->get_billing_country() : null,
						'billing_state'    => $order->get_billing_state() ? $order->get_billing_state() : null,
						'billing_postcode' => $order->get_billing_postcode() ? $order->get_billing_postcode() : null,
						'billing_city'     => $order->get_billing_city() ? $order->get_billing_city() : null,
					)
				);
				WC()->customer->save();

				if ( ! empty( $_POST['terms-field'] ) && empty( $_POST['terms'] ) ) {
					wc_add_notice( __( 'Please read and accept the terms and conditions to proceed with your order.', 'woocommerce' ), 'error' );
					return;
				}

				// Update payment method.
				if ( $order->needs_payment() ) {
					try {
						$payment_method_id = isset( $_POST['payment_method'] ) ? wc_clean( wp_unslash( $_POST['payment_method'] ) ) : false;

						if ( ! $payment_method_id ) {
							throw new Exception( __( 'Invalid payment method.', 'woocommerce' ) );
						}

						$available_gateways = WC()->payment_gateways->get_available_payment_gateways();
						$payment_method     = isset( $available_gateways[ $payment_method_id ] ) ? $available_gateways[ $payment_method_id ] : false;

						if ( ! $payment_method ) {
							throw new Exception( __( 'Invalid payment method.', 'woocommerce' ) );
						}

						$order->set_payment_method( $payment_method );
						$order->save();

						$payment_method->validate_fields();

						if ( 0 === wc_notice_count( 'error' ) ) {

							$result = $payment_method->process_payment( $order_id );

							// Redirect to success/confirmation/payment page.
							if ( isset( $result['result'] ) && 'success' === $result['result'] ) {
								$result = apply_filters( 'woocommerce_payment_successful_result', $result, $order_id );

								wp_redirect( $result['redirect'] ); //phpcs:ignore WordPress.Security.SafeRedirect.wp_redirect_wp_redirect
								exit;
							}
						}
					} catch ( Exception $e ) {
						wc_add_notice( $e->getMessage(), 'error' );
					}
				} else {
					// No payment was required for order.
					$order->payment_complete();
					wp_safe_redirect( $order->get_checkout_order_received_url() );
					exit;
				}

				do_action( 'woocommerce_after_pay_action', $order );

			}
		}
	}