FIXED: Discount fixed amount whole cart applied mutiple time when customer use Check Out with Multiple Addresses

app/code/Magento/SalesRule/Model/Rule/Action/Discount/CartFixed.php

@@ -64,25 +64,13 @@ public function calculate($rule, $item, $qty)
         $ruleTotals = $this->validator->getRuleItemTotalsInfo($rule->getId());
 
         $quote = $item->getQuote();
-        $address = $item->getAddress();
 
         $itemPrice = $this->validator->getItemPrice($item);
         $baseItemPrice = $this->validator->getItemBasePrice($item);
         $itemOriginalPrice = $this->validator->getItemOriginalPrice($item);
         $baseItemOriginalPrice = $this->validator->getItemBaseOriginalPrice($item);
 
-        /**
-         * prevent applying whole cart discount for every shipping order, but only for first order
-         */
-        if ($quote->getIsMultiShipping()) {
-            $usedForAddressId = $this->getCartFixedRuleUsedForAddress($rule->getId());
-            if ($usedForAddressId && $usedForAddressId != $address->getId()) {
-                return $discountData;
-            } else {
-                $this->setCartFixedRuleUsedForAddress($rule->getId(), $address->getId());
-            }
-        }
-        $cartRules = $address->getCartFixedRules();
+        $cartRules = $quote->getCartFixedRules();
         if (!isset($cartRules[$rule->getId()])) {
             $cartRules[$rule->getId()] = $rule->getDiscountAmount();
         }
@@ -122,14 +110,15 @@ public function calculate($rule, $item, $qty)
             $discountData->setOriginalAmount(min($itemOriginalPrice * $qty, $quoteAmount));
             $discountData->setBaseOriginalAmount($this->priceCurrency->round($baseItemOriginalPrice));
         }
-        $address->setCartFixedRules($cartRules);
+        $quote->setCartFixedRules($cartRules);
 
         return $discountData;
     }
 
     /**
      * Set information about usage cart fixed rule by quote address
      *
+     * @deprecated should be removed as it is not longer used
      * @param int $ruleId
      * @param int $itemId
      * @return void
@@ -142,6 +131,7 @@ protected function setCartFixedRuleUsedForAddress($ruleId, $itemId)
     /**
      * Retrieve information about usage cart fixed rule by quote address
      *
+     * @deprecated should be removed as it is not longer used
      * @param int $ruleId
      * @return int|null
      */

app/code/Magento/SalesRule/Model/Rule/QuoteResetAppliedRules.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\SalesRule\Model\Rule;
+
+use Magento\SalesRule\Model\Spi\QuoteResetAppliedRulesInterface;
+
+/**
+ * Reset applied rules to quote
+ */
+class QuoteResetAppliedRules implements QuoteResetAppliedRulesInterface
+{
+    /**
+     * @inheritDoc
+     */
+    public function execute(\Magento\Quote\Api\Data\CartInterface $quote): void
+    {
+        $quote->setCartFixedRules([]);
+    }
+}

app/code/Magento/SalesRule/Model/Spi/QuoteResetAppliedRulesInterface.php

@@ -0,0 +1,22 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\SalesRule\Model\Spi;
+
+/**
+ * Reset applied rules to quote
+ */
+interface QuoteResetAppliedRulesInterface
+{
+    /**
+     * Reset applied rules to quote
+     *
+     * @param \Magento\Quote\Api\Data\CartInterface $quote
+     * @return void
+     */
+    public function execute(\Magento\Quote\Api\Data\CartInterface $quote): void;
+}

app/code/Magento/SalesRule/Observer/QuoteResetAppliedRulesObserver.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\SalesRule\Observer;
+
+use Magento\Framework\Event\Observer;
+use Magento\Framework\Event\ObserverInterface;
+use Magento\SalesRule\Model\Spi\QuoteResetAppliedRulesInterface;
+
+/**
+ * Reset applied rules to quote before collecting totals
+ */
+class QuoteResetAppliedRulesObserver implements ObserverInterface
+{
+    /**
+     * @var QuoteResetAppliedRulesInterface
+     */
+    private $resetAppliedRules;
+
+    /**
+     * @param QuoteResetAppliedRulesInterface $resetAppliedRules
+     */
+    public function __construct(QuoteResetAppliedRulesInterface $resetAppliedRules)
+    {
+        $this->resetAppliedRules = $resetAppliedRules;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function execute(Observer $observer)
+    {
+        $this->resetAppliedRules->execute($observer->getQuote());
+    }
+}

app/code/Magento/SalesRule/Test/Unit/Model/Rule/Action/Discount/CartFixedTest.php

@@ -65,10 +65,17 @@ protected function setUp()
         $this->item = $this->createMock(\Magento\Quote\Model\Quote\Item\AbstractItem::class);
         $this->data = $this->createPartialMock(\Magento\SalesRule\Model\Rule\Action\Discount\Data::class, []);
 
-        $this->quote = $this->createMock(\Magento\Quote\Model\Quote::class);
+        $this->quote = $this->createPartialMock(
+            \Magento\Quote\Model\Quote::class,
+            [
+                'getStore',
+                'getCartFixedRules',
+                'setCartFixedRules',
+            ]
+        );
         $this->address = $this->createPartialMock(
             \Magento\Quote\Model\Quote\Address::class,
-            ['getCartFixedRules', 'setCartFixedRules', '__wakeup']
+            ['__wakeup']
         );
         $this->item->expects($this->any())->method('getQuote')->will($this->returnValue($this->quote));
         $this->item->expects($this->any())->method('getAddress')->will($this->returnValue($this->address));
@@ -101,7 +108,7 @@ public function testCalculate()
     {
         $this->rule->setData(['id' => 1, 'discount_amount' => 10.0]);
 
-        $this->address->expects($this->any())->method('getCartFixedRules')->will($this->returnValue([]));
+        $this->quote->expects($this->any())->method('getCartFixedRules')->will($this->returnValue([]));
         $store = $this->createMock(\Magento\Store\Model\Store::class);
         $this->priceCurrency->expects($this->atLeastOnce())->method('convert')->will($this->returnArgument(0));
         $this->priceCurrency->expects($this->atLeastOnce())->method('round')->will($this->returnArgument(0));
@@ -145,7 +152,7 @@ public function testCalculate()
             $this->returnValue(100)
         );
 
-        $this->address->expects($this->once())->method('setCartFixedRules')->with([1 => 0.0]);
+        $this->quote->expects($this->once())->method('setCartFixedRules')->with([1 => 0.0]);
         $this->model->calculate($this->rule, $this->item, 1);
 
         $this->assertEquals($this->data->getAmount(), 10);

app/code/Magento/SalesRule/etc/di.xml

@@ -36,6 +36,8 @@
                 type="Magento\SalesRule\Model\Data\DiscountData" />
     <preference for="Magento\SalesRule\Model\Spi\RuleQuoteRecollectTotalsInterface"
                 type="\Magento\SalesRule\Model\Rule\RuleQuoteRecollectTotalsOnDemand" />
+    <preference for="Magento\SalesRule\Model\Spi\QuoteResetAppliedRulesInterface"
+                type="\Magento\SalesRule\Model\Rule\QuoteResetAppliedRules" />
     <type name="Magento\SalesRule\Helper\Coupon">
         <arguments>
             <argument name="couponParameters" xsi:type="array">

app/code/Magento/SalesRule/etc/events.xml

@@ -36,4 +36,7 @@
     <event name="salesrule_rule_delete_after">
         <observer name="salesrule_quote_recollect_totals_on_delete" instance="\Magento\SalesRule\Observer\RuleQuoteRecollectTotalsObserver" />
     </event>
+    <event name="sales_quote_collect_totals_before">
+        <observer name="salesrule_sales_quote_collect_totals_before" instance="\Magento\SalesRule\Observer\QuoteResetAppliedRulesObserver" />
+    </event>
 </config>