AutomateWoo - Custom Subscription Rule based on Billing Period

functions.php

<?php

// Do NOT include the opening php tag

add_filter( 'automatewoo/rules/includes', 'wpdesk_automatewoo_rules' );
/**
 * Custom Rules
 *
 */
function wpdesk_automatewoo_rules( $rules ) {

	$rules['subscription_billing_period'] = dirname(__FILE__) . '/subscription-billing-period.php';

	return $rules;
}

subscription-billing-period.php

<?php

// Do NOT include the opening php tag

class WPDesk_AW_Rule_Subscription_Billing_Period extends AutomateWoo\Rules\Abstract_Select {

	public $data_item = 'subscription';

	function init() {
		$this->title = __( 'Subscription - Billing Period', 'wpdesk' );
		$this->group = __( 'Subscription', 'wpdesk' );
	}

	/**
	 * @return array
	 */
	function load_select_choices() {
		return wcs_get_subscription_period_strings();
	}

	/**
	 * @param \WC_Subscription $subscription
	 * @param $compare
	 * @param $value
	 * @return bool
	 */
	function validate( $subscription, $compare, $value ) {
		return $this->validate_select( $subscription->get_billing_period(), $compare, $value );
	}

}

return new WPDesk_AW_Rule_Subscription_Billing_Period();