From 4ea396aab16326d7c8463c7d600e3b5b94c1fd56 Mon Sep 17 00:00:00 2001
From: Mike Jolley <mike.jolley@me.com>
Date: Thu, 25 Aug 2016 15:58:30 +0100
Subject: [PATCH] When deleting a tax rate class, remove its rates

Closes #11759
---
 includes/class-wc-tax.php | 23 +++++++++++++++++++++++
 readme.txt                |  1 +
 2 files changed, 24 insertions(+)

diff --git a/includes/class-wc-tax.php b/includes/class-wc-tax.php
index 318164655cc..606d10c5d1a 100644
--- a/includes/class-wc-tax.php
+++ b/includes/class-wc-tax.php
@@ -37,6 +37,29 @@ class WC_Tax {
 	public static function init() {
 		self::$precision         = wc_get_rounding_precision();
 		self::$round_at_subtotal = 'yes' === get_option( 'woocommerce_tax_round_at_subtotal' );
+		add_action( 'update_option_woocommerce_tax_classes', array( __CLASS__, 'maybe_remove_tax_class_rates' ), 10, 2 );
+	}
+
+	/**
+	 * When the woocommerce_tax_classes option is changed, remove any orphan rates.
+	 * @param  string $old_value
+	 * @param  string $value
+	 */
+	public static function maybe_remove_tax_class_rates( $old_value, $value ) {
+		$old     = array_filter( array_map( 'trim', explode( "\n", $old_value ) ) );
+		$new     = array_filter( array_map( 'trim', explode( "\n", $value ) ) );
+		$removed = array_filter( array_map( 'sanitize_title', array_diff( $old, $new ) ) );
+
+		if ( $removed ) {
+			global $wpdb;
+
+			foreach ( $removed as $removed_tax_class ) {
+				$wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}woocommerce_tax_rates WHERE tax_rate_class = %s;", $removed_tax_class ) );
+				$wpdb->query( "DELETE locations FROM {$wpdb->prefix}woocommerce_tax_rate_locations locations LEFT JOIN {$wpdb->prefix}woocommerce_tax_rates rates ON rates.tax_rate_id = locations.tax_rate_id WHERE rates.tax_rate_id IS NULL;" );
+			}
+
+			WC_Cache_Helper::incr_cache_prefix( 'taxes' );
+		}
 	}
 
 	/**
diff --git a/readme.txt b/readme.txt
index 1c92f21ee97..17b02c97f85 100644
--- a/readme.txt
+++ b/readme.txt
@@ -178,6 +178,7 @@ Yes you can! Join in on our [GitHub repository](http://github.com/woothemes/wooc
 * Allow oAuth1.0a authentication using headers.
 * Removed internal scroll from log viewer.
 * Add reply-to to admin emails.
+* When deleting a tax rate class, remove it's tax rates.
 
 [See changelog for all versions](https://raw.githubusercontent.com/woothemes/woocommerce/master/CHANGELOG.txt).