Ensures billing fields are properly copied from shipping address when billing address is optional and "same as shipping" is selected.

gistfile1.txt

if ( ! class_exists( 'WFACP_Billing_Field_Copy_Handler' ) ) {
	class WFACP_Billing_Field_Copy_Handler {

		/**
		 * Fields that should be copied from shipping to billing
		 *
		 * @var array
		 */
		private $copy_fields = array(
			'first_name',
			'last_name',
			'company',
			'address_1',
			'address_2',
			'city',
			'state',
			'postcode',
			'country',
			'phone',
		);

		/**
		 * Constructor - Register hooks
		 */
		public function __construct() {
			// High priority to ensure it runs after WFACP's own processing
			add_filter( 'woocommerce_checkout_posted_data', array( $this, 'copy_shipping_to_billing' ), 999 );
			add_action( 'woocommerce_checkout_process', array( $this, 'validate_billing_fields' ), 5 );
		}

		/**
		 * Copy shipping address to billing when billing same as shipping is checked
		 *
		 * @param array $data Posted checkout data
		 * @return array Modified checkout data
		 */
		public function copy_shipping_to_billing( $data ) {
			// Only proceed if this is a WFACP checkout
			if ( ! isset( $_POST['_wfacp_post_id'] ) ) {
				return $data;
			}

			// Check if billing same as shipping is enabled
			$billing_same_as_shipping = isset( $_POST['billing_same_as_shipping'] ) ? absint( $_POST['billing_same_as_shipping'] ) : 0;

			// Check if user has NOT opted for different billing address
			$ship_to_different = isset( $_POST['ship_to_different_address'] ) ? absint( $_POST['ship_to_different_address'] ) : 0;

			// Only copy if billing same as shipping is checked OR ship to different is not checked
			if ( 1 !== $billing_same_as_shipping && 1 === $ship_to_different ) {
				return $data;
			}

			// Copy each shipping field to corresponding billing field
			foreach ( $this->copy_fields as $field ) {
				$shipping_key = 'shipping_' . $field;
				$billing_key  = 'billing_' . $field;

				// If shipping field exists and has value
				if ( isset( $data[ $shipping_key ] ) && ! empty( $data[ $shipping_key ] ) ) {
					// Copy to billing if billing is empty
					if ( ! isset( $data[ $billing_key ] ) || empty( $data[ $billing_key ] ) ) {
						$data[ $billing_key ] = $data[ $shipping_key ];
					}
				}
			}

			return $data;
		}

		/**
		 * Validate that required billing fields are not empty
		 * when billing address should be same as shipping
		 *
		 * @return void
		 */
		public function validate_billing_fields() {
			// Only proceed if this is a WFACP checkout
			if ( ! isset( $_POST['_wfacp_post_id'] ) ) {
				return;
			}

			// Check if billing same as shipping is enabled
			$billing_same_as_shipping = isset( $_POST['billing_same_as_shipping'] ) ? absint( $_POST['billing_same_as_shipping'] ) : 0;

			// Only validate if billing same as shipping is checked
			if ( 1 !== $billing_same_as_shipping ) {
				return;
			}

			// Required fields that must be copied
			$required_fields = array(
				'first_name' => __( 'First name', 'woocommerce' ),
				'last_name'  => __( 'Last name', 'woocommerce' ),
				'address_1'  => __( 'Street address', 'woocommerce' ),
				'city'       => __( 'Town / City', 'woocommerce' ),
				'postcode'   => __( 'Postcode / ZIP', 'woocommerce' ),
				'country'    => __( 'Country / Region', 'woocommerce' ),
			);

			// Check each required field
			foreach ( $required_fields as $field => $label ) {
				$shipping_key = 'shipping_' . $field;
				$billing_key  = 'billing_' . $field;

				// If shipping field has value, copy it to billing
				if ( isset( $_POST[ $shipping_key ] ) && ! empty( $_POST[ $shipping_key ] ) ) {
					if ( ! isset( $_POST[ $billing_key ] ) || empty( $_POST[ $billing_key ] ) ) {
						$_POST[ $billing_key ] = sanitize_text_field( wp_unslash( $_POST[ $shipping_key ] ) );
					}
				}
			}
		}
	}

	// Initialize the handler
	new WFACP_Billing_Field_Copy_Handler();
}