baseline: 批次A-D 成果 + membership 半成品（测试红）

2026-09-11 23:11:35 +08:00
commit b3f3095d53
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+"""往来单位服务：开单取价 + 信用额度。
+
+取价优先级（quote_price）：
+1. 客户专属价 CustomerProductPrice
+2. 价格等级价 PriceLevel.discount_rate × 默认售价（rate>0 且 <1 时生效）
+3. 最近成交价（该客户+商品最近一张已过账销售单行单价）
+4. 默认售价 Product.sale_price
+"""
+
+from __future__ import annotations
+
+from decimal import Decimal
+
+from .models import Customer, CustomerProductPrice, PriceLevel
+
+
+def quote_price(*, tenant, customer: Customer, product) -> dict:
+    """返回 {price, source, last_price, min_price, max_price}。
+
+    price 为基本单位价；last/min/max 为该客户历史成交参考（基本单位口径）。
+    """
+    # 1. 客户专属价
+    cpp = CustomerProductPrice.objects.filter(
+        tenant=tenant, customer=customer, product=product
+    ).first()
+    if cpp is not None:
+        price, source = cpp.price, "customer"
+    else:
+        # 2. 价格等级价
+        level: PriceLevel | None = customer.price_level
+        rate = level.discount_rate if level else Decimal("0")
+        if rate and Decimal("0") < rate < Decimal("1"):
+            price, source = product.sale_price * rate, "level"
+        else:
+            # 3. 最近成交价
+            last = _history(tenant, customer, product).first()
+            if last is not None:
+                price, source = last.unit_price, "last"
+            else:
+                price, source = product.sale_price, "default"
+
+    hist = list(_history(tenant, customer, product).values_list(
+        "unit_price", flat=True
+    )[:50])
+    return {
+        "price": price,
+        "source": source,
+        "last_price": hist[0] if hist else None,
+        "min_price": min(hist) if hist else None,
+        "max_price": max(hist) if hist else None,
+    }
+
+
+def _history(tenant, customer: Customer, product):
+    """该客户+商品的已过账销售行（新→旧）。"""
+    from apps.sales.models import SalesBillLine
+
+    return (
+        SalesBillLine.objects.filter(
+            tenant=tenant,
+            bill__customer=customer,
+            bill__state="confirmed",
+            product=product,
+        )
+        .order_by("-bill_id", "-id")
+    )
+
+
+def credit_usage(*, tenant, customer: Customer) -> dict:
+    """客户信用额度占用：{limit, outstanding, available}。
+
+    limit=0 表示未启用管控；available = limit - outstanding（未启用时为 None）。
+    """
+    from django.db.models import Sum
+
+    from apps.finance.models import Receivable
+
+    agg = Receivable.objects.filter(
+        tenant=tenant,
+        customer=customer,
+        status__in=["open", "partial"],
+        is_deleted=False,
+    ).aggregate(total=Sum("total_amount"), paid=Sum("paid_amount"))
+    outstanding = ((agg["total"] or Decimal("0")) - (agg["paid"] or Decimal("0"))).quantize(
+        Decimal("0.0001")
+    )
+    limit = customer.credit_limit or Decimal("0")
+    return {
+        "limit": limit,
+        "outstanding": outstanding,
+        "available": (limit - outstanding) if limit > 0 else None,
+    }
+
+
+def check_credit(*, tenant, customer: Customer, extra_amount: Decimal) -> dict:
+    """下单/过账前检查额度。返回 usage；超限抛 CreditLimitExceeded。"""
+    from apps.sales.services import CreditLimitExceeded
+
+    usage = credit_usage(tenant=tenant, customer=customer)
+    if usage["limit"] <= 0:
+        return usage
+    if usage["outstanding"] + extra_amount > usage["limit"]:
+        raise CreditLimitExceeded(
+            customer.code, usage["outstanding"], usage["limit"], extra_amount
+        )
+    return usage