修复已优惠金额大于合计的问题

Components/BUserOrder/src/main/java/com/yidian/shenghuoquan/buserorder/viewmodel/ConfirmOrderViewModel.kt

@@ -115,11 +115,15 @@ class ConfirmOrderViewModel : BaseViewModel() {
 
   /**
    * 计算商品合计 = 原价 - 优惠
+   * 已优惠金额 = 优惠券金额（但不能大于合计）
    */
   private fun calculateTotalAmount() {
     var total = originalAmount - couponAmount
     if (total < 0) {
       total = 0.00
+      couponAmountValue.value = originalAmount
+    } else {
+      couponAmountValue.value = couponAmount
     }
     totalAmount.value = total
   }
@@ -166,8 +170,6 @@ class ConfirmOrderViewModel : BaseViewModel() {
       }
     }
     selectedCouponList.value = list
-    // 更新优惠券总金额
-    couponAmountValue.value = couponAmount
     // 更新选择优惠券名称
     couponNameValue.value = couponsAvailableList.value?.get(0)?.name
     // 重新计算相关金额