MAGETWO-51096: Wrong discount for order with Cart Price Rule and settings Apply to Shipping Amount = YES

Author: valdislav

app/code/Magento/SalesRule/view/adminhtml/ui_component/sales_rule_form.xml

@@ -437,6 +437,7 @@
         <field name="apply_to_shipping">
             <argument name="data" xsi:type="array">
                 <item name="config" xsi:type="array">
+                    <item name="component" xsi:type="string">Magento_Ui/js/form/element/single-checkbox-toggle-notice</item>
                     <item name="dataType" xsi:type="string">boolean</item>
                     <item name="formElement" xsi:type="string">checkbox</item>
                     <item name="source" xsi:type="string">sales_rule</item>
@@ -445,8 +446,9 @@
                         <item name="true" xsi:type="number">1</item>
                         <item name="false" xsi:type="number">0</item>
                     </item>
-                    <item name="notice" xsi:type="string" translate="true">
-                        If is checked discount amount will be applied to subtotal and shipping amount separately
+                    <item name="notices" xsi:type="array">
+                        <item name="0" xsi:type="string" translate="true">Discount amount is applied to subtotal only</item>
+                        <item name="1" xsi:type="string" translate="true">Discount amount is applied to subtotal and shipping amount separately</item>
                     </item>
                     <item name="default" xsi:type="number">0</item>
                     <item name="label" xsi:type="string" translate="true">Apply to Shipping Amount</item>

app/code/Magento/Ui/view/base/web/js/form/element/single-checkbox-toggle-notice.js

@@ -0,0 +1,51 @@
+/**
+ * Copyright © 2016 Magento. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+define([
+    'Magento_Ui/js/form/element/single-checkbox'
+], function (SingleCheckbox) {
+    'use strict';
+
+    return SingleCheckbox.extend({
+        defaults: {
+            notices: [],
+            tracks: {
+                notice: true
+            }
+        },
+
+        /**
+         * Choose notice on initialization
+         *
+         * @returns {*|void|Element}
+         */
+        initialize: function () {
+            this._super()
+                .chooseNotice();
+
+            return this;
+        },
+
+        /**
+         * Choose notice function
+         *
+         * @returns {void}
+         */
+        chooseNotice: function () {
+            var checkedNoticeNumber = Number(this.checked());
+            this.notice = this.notices[checkedNoticeNumber];
+        },
+
+        /**
+         * Choose notice on update
+         *
+         * @returns {void}
+         */
+        onUpdate: function () {
+            this._super();
+            this.chooseNotice();
+        }
+    });
+});