From f355f9e40ba17e133b20e3a6b90d9847b114363a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=9D=99?= <lym125@gmail.com>
Date: Fri, 17 Dec 2021 14:35:12 +0800
Subject: [PATCH] WIP

---
 app/Services/OrderService.php | 67 +++++++++++++++--------------------
 1 file changed, 28 insertions(+), 39 deletions(-)

diff --git a/app/Services/OrderService.php b/app/Services/OrderService.php
index 87d6f114..62200231 100644
--- a/app/Services/OrderService.php
+++ b/app/Services/OrderService.php
@@ -482,49 +482,38 @@ class OrderService
             throw new BizException('优惠券不满足使用条件');
         }
 
-        // 商品的券折扣金额
-        $discountAmounts = [];
-        // 优惠券折扣总额
-        $discountTotalAmount = 0;
-        // 未计算优惠金额的商品总数
-        $lastCount = count($amounts);
-
-        foreach ($amounts as $skuId => $amount) {
+        // 优惠券折扣金额
+        $couponAmount = value(function ($coupon, $totalAmount) {
+            // 如果优惠券是折扣券，则需算出优惠总额
             if ($coupon->isDiscountCoupon()) {
-                /*
-                |----------------------------------------
-                | 计算折扣券的折扣金额
-                |----------------------------------------
-                */
-
-                $discountAmounts[$skuId] = (int) bcmul($amount, bcdiv(100 - $coupon->coupon_amount, 100, 2));
-            } else {
-                /*
-                |----------------------------------------
-                | 计算抵扣券的抵扣金额
-                |----------------------------------------
-                */
-
-                $couponAmount = $coupon->coupon_amount;
-
-                // 如果券的抵用金额大于商品的实际金额，则以商品实际金额作为抵扣金额
-                if ($couponAmount > $totalAmount) {
-                    $couponAmount = $totalAmount;
-                }
-
-                $discountAmounts[$skuId] = (int) ($couponAmount * $amount / $totalAmount);
-                $discountTotalAmount += $discountAmounts[$skuId];
-
-                $lastCount--;
-
-                // 将券的剩余抵扣金额给最后一个商品
-                if ($lastCount === 0) {
-                    $discountAmounts[$skuId] += $couponAmount - $discountTotalAmount;
-                }
+                return (int) bcmul($totalAmount, bcdiv(100 - $coupon->coupon_amount, 100, 2));
             }
+
+            // 如果优惠券的折扣金额超过商品总额，则优惠金额为商品总额
+            if ($coupon->coupon_amount > $totalAmount) {
+                return $totalAmount;
+            }
+
+            return $coupon->coupon_amount;
+        }, $coupon, $totalAmount);
+
+        // 待计算优惠的商品总数
+        $i = count($amounts);
+
+        foreach ($amounts as &$amount) {
+            $i--;
+
+            if ($i > 0) {
+                $amount = (int) bcdiv(bcmul($couponAmount, $amount, 0), $totalAmount, 2);
+                $couponAmount -= $amount;
+            } else {
+                $amount = $couponAmount;
+            }
+
+            unset($amount);
         }
 
-        return $discountAmounts;
+        return $amounts;
     }
 
     /**