[AutomateWoo] Display text dynamically based on the number of items in an order. More info at https://automatewoo.com/docs/variables/custom-variables/

functions.php

<?php
/**
 * Add the custom variable to the list
 */
add_filter( 'automatewoo/variables', 'my_automatewoo_variables' );

/**
 * @param $variables array
 * @return array
 */
function my_automatewoo_variables( $variables ) {
	// variable's string form is set here, it will be order.pluralize
	$variables['order']['pluralize'] = dirname(__FILE__) . '/variable-order-pluralize.php';
	return $variables;
}

variable-order-pluralize.php

<?php

if ( ! defined( 'ABSPATH' ) ) exit;

/**
 * @class AW_Variable_Order_Pluralize
 */
class My_AutomateWoo_Variable_Order_Pluralize extends AutomateWoo\Variable {

	/** @var bool - whether to allow setting a fallback value for this variable  */
	public $use_fallback = false;

	
	public function load_admin_details() {
		$this->description = __( "Display text dynamically based on the number of items in an order.", 'automatewoo');
		
		// setting parameters fields is optional
		$this->add_parameter_text_field( 'single', __( 'Used when there is one item purchased.', 'your-text-domain' ) );
		$this->add_parameter_text_field( 'plural', __( 'Used when there are more than one item purchased.', 'your-text-domain' ) );
	}

	/**
	 * @param $order WC_Order
	 * @param $parameters array
	 * @return string
	 */
	public function get_value( $order, $parameters ) {
		$single = isset( $parameters['single'] ) ? $parameters['single'] : '';
		$plural = isset( $parameters['plural'] ) ? $parameters['plural'] : '';

		return $order->get_item_count() == 1 ? $single : $plural;
	}

}

return new My_AutomateWoo_Variable_Order_Pluralize();