From 2d2aeb002fa3a100ea861e4cb6fb8ce6f9865a9c Mon Sep 17 00:00:00 2001
From: Matt Allan <matt.allan@automattic.com>
Date: Mon, 15 Apr 2024 08:02:20 +1000
Subject: [PATCH] Fixes "Invalid recurring shipping method" errors when
 purchasing multiple subscriptions with Apple / Google Pay (#8618)

---
 ...8029-prb-invalid-recurring-shipping-method |  4 ++
 ...ayments-payment-request-button-handler.php | 40 ++++++++++++++++++-
 psalm-baseline.xml                            |  4 +-
 3 files changed, 44 insertions(+), 4 deletions(-)
 create mode 100644 changelog/fix-8029-prb-invalid-recurring-shipping-method

diff --git a/changelog/fix-8029-prb-invalid-recurring-shipping-method b/changelog/fix-8029-prb-invalid-recurring-shipping-method
new file mode 100644
index 00000000000..2dd0f954958
--- /dev/null
+++ b/changelog/fix-8029-prb-invalid-recurring-shipping-method
@@ -0,0 +1,4 @@
+Significance: minor
+Type: fix
+
+Resolves "Invalid recurring shipping method" errors when purchasing multiple subscriptions with Apple Pay and Google Pay.
diff --git a/includes/class-wc-payments-payment-request-button-handler.php b/includes/class-wc-payments-payment-request-button-handler.php
index 92ce89c7b94..d4f8c568a87 100644
--- a/includes/class-wc-payments-payment-request-button-handler.php
+++ b/includes/class-wc-payments-payment-request-button-handler.php
@@ -893,7 +893,7 @@ public function get_shipping_options( $shipping_address, $itemized_display_items
 			$data = [];
 
 			// Remember current shipping method before resetting.
-			$chosen_shipping_methods = WC()->session->get( 'chosen_shipping_methods' );
+			$chosen_shipping_methods = WC()->session->get( 'chosen_shipping_methods', [] );
 			$this->calculate_shipping( apply_filters( 'wcpay_payment_request_shipping_posted_values', $shipping_address ) );
 
 			$packages = WC()->shipping->get_packages();
@@ -943,6 +943,8 @@ public function get_shipping_options( $shipping_address, $itemized_display_items
 
 			WC()->cart->calculate_totals();
 
+			$this->maybe_restore_recurring_chosen_shipping_methods( $chosen_shipping_methods );
+
 			$data          += $this->express_checkout_helper->build_display_items( $itemized_display_items );
 			$data['result'] = 'success';
 		} catch ( Exception $e ) {
@@ -1507,4 +1509,40 @@ private function get_taxes_like_cart( $product, $price ) {
 		// Normally there should be a single tax, but `calc_tax` returns an array, let's use it.
 		return WC_Tax::calc_tax( $price, $rates, false );
 	}
+
+	/**
+	 * Restores the shipping methods previously chosen for each recurring cart after shipping was reset and recalculated
+	 * during the Payment Request get_shipping_options flow.
+	 *
+	 * When the cart contains multiple subscriptions with different billing periods, customers are able to select different shipping
+	 * methods for each subscription, however, this is not supported when purchasing with Apple Pay and Google Pay as it's
+	 * only concerned about handling the initial purchase.
+	 *
+	 * In order to avoid Woo Subscriptions's `WC_Subscriptions_Cart::validate_recurring_shipping_methods` throwing an error, we need to restore
+	 * the previously chosen shipping methods for each recurring cart.
+	 *
+	 * This function needs to be called after `WC()->cart->calculate_totals()` is run, otherwise `WC()->cart->recurring_carts` won't exist yet.
+	 *
+	 * @param array $previous_chosen_methods The previously chosen shipping methods.
+	 */
+	private function maybe_restore_recurring_chosen_shipping_methods( $previous_chosen_methods = [] ) {
+		if ( empty( WC()->cart->recurring_carts ) || ! method_exists( 'WC_Subscriptions_Cart', 'get_recurring_shipping_package_key' ) ) {
+			return;
+		}
+
+		$chosen_shipping_methods = WC()->session->get( 'chosen_shipping_methods', [] );
+
+		foreach ( WC()->cart->recurring_carts as $recurring_cart_key => $recurring_cart ) {
+			foreach ( $recurring_cart->get_shipping_packages() as $recurring_cart_package_index => $recurring_cart_package ) {
+				$package_key = WC_Subscriptions_Cart::get_recurring_shipping_package_key( $recurring_cart_key, $recurring_cart_package_index );
+
+				// If the recurring cart package key is found in the previous chosen methods, but not in the current chosen methods, restore it.
+				if ( isset( $previous_chosen_methods[ $package_key ] ) && ! isset( $chosen_shipping_methods[ $package_key ] ) ) {
+					$chosen_shipping_methods[ $package_key ] = $previous_chosen_methods[ $package_key ];
+				}
+			}
+		}
+
+		WC()->session->set( 'chosen_shipping_methods', $chosen_shipping_methods );
+	}
 }
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index ecb5ea1088e..17038230df6 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -25,11 +25,9 @@
     </UndefinedClass>
   </file>
   <file src="includes/class-wc-payments-payment-request-button-handler.php">
-    <UndefinedClass occurrences="4">
+    <UndefinedClass occurrences="5">
       <code>WC_Pre_Orders_Product</code>
       <code>WC_Subscriptions_Product</code>
-      <code>WC_Subscriptions_Product</code>
-      <code>WC_Subscriptions_Cart</code>
       <code>WC_Subscriptions_Cart</code>
     </UndefinedClass>
   </file>