<?php

function deactivate_paypal_unless_subscription( $available_gateways ) {

	global $wp;

	if ( class_exists( 'WC_Subscriptions_Cart' ) ) {

		// version 1.5 and 2.0 compatibility
		$cart_contains_renewal = function_exists( 'wcs_cart_contains_renewal' ) ? wcs_cart_contains_renewal() : WC_Subscriptions_Cart::cart_contains_subscription_renewal();

		if ( is_checkout_pay_page() ) {
			$order_contains_renewal = function_exists( 'wcs_order_contains_subscription' ) ? wcs_order_contains_subscription( $wp->query_vars['order-pay'] ) : WC_Subscriptions_Order::order_contains_subscription( $wp->query_vars['order-pay'] );
		} else {
			$order_contains_renewal = false;
		}

		if ( ! WC_Subscriptions_Cart::cart_contains_subscription() || ! $cart_contains_renewal || ! $order_contains_renewal || ! WC_Subscriptions_Change_Payment_Gateway::$is_request_to_change_payment ) {
			if ( isset( $available_gateways['paypal'] ) ) {
				unset( $available_gateways['paypal'] );
			}
		}
	} else {
		if ( isset( $available_gateways['paypal'] ) ) {
			unset( $available_gateways['paypal'] );
		}
	}

	return $available_gateways;
}
add_filter( 'woocommerce_available_payment_gateways', 'deactivate_paypal_unless_subscription', 11 );