fix(coupon): 修复商户优惠券计算逻辑

- 修复折扣券计算逻辑，使用 BigDecimal 进行精确计算
- 优化满减券计算公式，确保计算结果更准确
- 添加金额处理，确保折后金额和优惠金额正确更新

src/main/java/com/xynet/marketing/service/factory/coupon/merc/impl/base/MercCouponFactoryBase.java

@@ -335,7 +335,8 @@ public class MercCouponFactoryBase extends ServiceImpl<MercCouponMapper, MercCou
             if (Objects.equals(mercCoupon.getType(), CouponTypeEnum.T_2.getCode())) {
                 JSONObject priceJson = JSONUtil.parseObj(mercCoupon.getPrice());
                 BigDecimal scalar = new BigDecimal(priceJson.getStr("scalar"));
-                goods.set("priceOnsale", goods.getInt("priceOnsale") * scalar.doubleValue());
+                goods.set("priceOnsale", scalar.multiply(goods.getBigDecimal("priceOnsale")).setScale(0, RoundingMode.CEILING).intValue());
+                goods.set("amount", scalar.multiply(goods.getBigDecimal("amount")).setScale(0, RoundingMode.CEILING).intValue());
                 goods.set("msg", goods.getString("msg") + priceJson.getStr("scalar").replace("0.", "") + "折券;");
             }
             //满减券
@@ -379,10 +380,9 @@ public class MercCouponFactoryBase extends ServiceImpl<MercCouponMapper, MercCou
                     BigDecimal zyh = new BigDecimal(priceOnsaleType1);
                     //计算公式：(单价*数量/总金额*总优惠)
                     Integer goodsYh = promotionPriceOnsale.multiply(num).divide(zje, 2, BigDecimal.ROUND_HALF_UP).multiply(zyh).setScale(0, RoundingMode.CEILING).intValue();
-
-                    Integer priceOnsale = promotionPriceOnsale.multiply(num).subtract(new BigDecimal(goodsYh)).intValue();
-
+                    Integer priceOnsale = promotionPriceOnsale.subtract(new BigDecimal(goodsYh).divide(num, 2, BigDecimal.ROUND_HALF_UP)).intValue();
                     goods.set("priceOnsale", priceOnsale);
+                    goods.set("amount", goods.getInt("amount") - goodsYh);
                     goods.set("msg", goods.getString("msg") + "满减券减：" + (goodsYh * 0.01) + "元;");
                 }
             }