From d10987d8139b26ed682e222b8683c16503fc74c2 Mon Sep 17 00:00:00 2001
From: Manos Psychogyiopoulos <psyx@somewherewarm.gr>
Date: Thu, 25 Jan 2018 16:40:31 +0200
Subject: [PATCH] Match saved (canonical) rate IDs against chosen rates

Generates canonical rate IDs (`method_id:instance_id`) from package rates and order shipping line items.

Requires https://github.com/woocommerce/woocommerce/pull/18483
---
 .../gateways/cod/class-wc-gateway-cod.php     | 67 +++++++++++++++++--
 1 file changed, 61 insertions(+), 6 deletions(-)

diff --git a/includes/gateways/cod/class-wc-gateway-cod.php b/includes/gateways/cod/class-wc-gateway-cod.php
index b4cf078fd97..542a7e2220e 100644
--- a/includes/gateways/cod/class-wc-gateway-cod.php
+++ b/includes/gateways/cod/class-wc-gateway-cod.php
@@ -182,15 +182,16 @@ class WC_Gateway_COD extends WC_Payment_Gateway {
 
 		// Only apply if all packages are being shipped via chosen method, or order is virtual.
 		if ( ! empty( $this->enable_for_methods ) && $needs_shipping ) {
-			$chosen_shipping_methods = array();
 
-			if ( is_object( $order ) ) {
-				$chosen_shipping_methods = array_unique( array_map( 'wc_get_string_before_colon', $order->get_shipping_methods() ) );
-			} elseif ( $chosen_shipping_methods_session = WC()->session->get( 'chosen_shipping_methods' ) ) {
-				$chosen_shipping_methods = array_unique( array_map( 'wc_get_string_before_colon', $chosen_shipping_methods_session ) );
+			$canonical_rate_ids = array();
+
+			if ( is_object( $order ) && ( $order_shipping_items = $order->get_shipping_methods() ) ) {
+				$canonical_rate_ids = $this->get_canonical_order_shipping_item_rate_ids( $order_shipping_items );
+			} elseif ( $chosen_package_rate_ids = WC()->session->get( 'chosen_shipping_methods' ) ) {
+				$canonical_rate_ids = $this->get_canonical_package_rate_ids( $chosen_package_rate_ids );
 			}
 
-			if ( 0 < count( array_diff( $chosen_shipping_methods, $this->enable_for_methods ) ) ) {
+			if ( ! sizeof( $this->get_matching_rates( $canonical_rate_ids ) ) ) {
 				return false;
 			}
 		}
@@ -198,6 +199,60 @@ class WC_Gateway_COD extends WC_Payment_Gateway {
 		return parent::is_available();
 	}
 
+	/**
+	 * Converts the chosen rate IDs generated by Shipping Methods to a canonical 'method_id:instance_id' format.
+	 *
+	 * @since  3.4.0
+	 *
+	 * @param  array  $order_shipping_items  Array of WC_Order_Item_Shipping objects.
+	 * @return array  $canonical_rate_ids    Rate IDs in a canonical format.
+	 */
+	private function get_canonical_order_shipping_item_rate_ids( $order_shipping_items ) {
+
+		$canonical_rate_ids = array();
+
+		foreach ( $order_shipping_items as $order_shipping_item ) {
+			$canonical_rate_ids[] = $order_shipping_item->get_method_id() . ':' . $order_shipping_item->get_instance_id();
+		}
+
+		return $canonical_rate_ids;
+	}
+
+	/**
+	 * Converts the chosen rate IDs generated by Shipping Methods to a canonical 'method_id:instance_id' format.
+	 *
+	 * @since  3.4.0
+	 *
+	 * @param  array  $rate_ids            Rate IDs as generated by shipping methods. Can be anything if a shipping method doesn't honor WC conventions.
+	 * @return array  $canonical_rate_ids  Rate IDs in a canonical format.
+	 */
+	private function get_canonical_package_rate_ids( $chosen_package_rate_ids ) {
+
+		$shipping_packages  = WC()->shipping->get_packages();
+		$canonical_rate_ids = array();
+
+		foreach ( $chosen_package_rate_ids as $package_key => $chosen_package_rate_id ) {
+			if ( ! empty( $shipping_packages[ $package_key ][ 'rates' ][ $chosen_package_rate_id ] ) ) {
+				$chosen_rate          = $shipping_packages[ $package_key ][ 'rates' ][ $chosen_package_rate_id ];
+				$canonical_rate_ids[] = $chosen_rate->get_method_id() . ':' . $chosen_rate->get_instance_id();
+			}
+		}
+
+		return $canonical_rate_ids;
+	}
+
+	/**
+	 * Indicates whether a rate exists in an array of canonically-formatted rate IDs that activates this gateway.
+	 *
+	 * @since  3.4.0
+	 *
+	 * @param  array  $rate_ids
+	 * @return boolean
+	 */
+	private function get_matching_rates( $rate_ids ) {
+		// First, match entries in 'method_id:instance_id' format. Then, match entries in 'method_id' format by stripping off the instance ID from the candidates.
+		return array_unique( array_merge( array_intersect( $this->enable_for_methods, $rate_ids ), array_intersect( $this->enable_for_methods, array_unique( array_map( 'wc_get_string_before_colon', $rate_ids ) ) ) ) );
+	}
 
 	/**
 	 * Process the payment and return the result.