"""P0 #5 信用额度落地集成测试。

覆盖：限额内通过、超限拒绝、force 放行+预警通知、接近 90% 预警、无限额不校验。
"""

import pytest
from datetime import date
from decimal import Decimal
from model_bakery import baker

from apps.catalog.models import Product
from apps.inventory.models import Warehouse
from apps.partner.models import Customer
from apps.finance.models import Receivable
from apps.notify.models import Notification
from apps.sales import services as sales_services
from apps.sales.services import CreditLimitExceeded


@pytest.fixture
def warehouse(db, tenant):
    return baker.make(Warehouse, tenant=tenant, code="WH01", name="主仓")


@pytest.fixture
def product(db, tenant):
    return baker.make(Product, tenant=tenant, code="P001", name="商品A",
                      sale_price=Decimal("100"))


@pytest.fixture
def customer(db, tenant):
    return baker.make(Customer, tenant=tenant, code="C001", name="受限客户",
                      credit_limit=Decimal("1000"))


def _stock_in(tenant, warehouse, product, qty):
    from apps.inventory import services as inv_services
    inv_services.inbound(
        tenant=tenant, warehouse=warehouse, product=product,
        quantity=Decimal(str(qty)), unit_cost=Decimal("50"),
    )


def _make_receivable(tenant, customer, amount, paid=0):
    return baker.make(
        Receivable, tenant=tenant, customer=customer, bill_no="RC-OLD",
        bill_date=date.today(), total_amount=Decimal(str(amount)),
        paid_amount=Decimal(str(paid)), status="partial" if paid else "open",
    )


def test_confirm_within_limit_passes(tenant, warehouse, customer, product):
    _make_receivable(tenant, customer, 400)
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=customer, warehouse=warehouse,
        lines=[{"product": product, "quantity": 5, "unit_price": 100}],  # 500
    )
    sales_services.confirm_sales_bill(bill)
    assert bill.state == "confirmed"


def test_confirm_over_limit_rejects_and_rolls_back(tenant, warehouse, customer, product):
    _make_receivable(tenant, customer, 700)
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=customer, warehouse=warehouse,
        lines=[{"product": product, "quantity": 5, "unit_price": 100}],  # 500 → 1200 > 1000
    )
    from apps.inventory.models import Stock
    with pytest.raises(CreditLimitExceeded):
        sales_services.confirm_sales_bill(bill)
    # 事务回滚：库存未扣、应收未生成、状态未变
    assert bill.state == "draft"
    assert Stock.objects.get(product=product).on_hand == Decimal("10")
    assert not Receivable.objects.filter(source_ref=bill.bill_no).exists()


def test_confirm_over_limit_force_passes_with_alert(tenant, warehouse, customer, product):
    _make_receivable(tenant, customer, 700)
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=customer, warehouse=warehouse,
        lines=[{"product": product, "quantity": 5, "unit_price": 100}],
    )
    sales_services.confirm_sales_bill(bill, force=True)
    assert bill.state == "confirmed"
    assert Notification.objects.filter(
        tenant=tenant, extra_data__forced=True
    ).count() == 1


def test_confirm_near_limit_warns(tenant, warehouse, customer, product):
    """占用达 90% 发预警但不阻断：400 旧账 + 500 新单 = 900 = 90%。"""
    _make_receivable(tenant, customer, 400)
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=customer, warehouse=warehouse,
        lines=[{"product": product, "quantity": 5, "unit_price": 100}],
    )
    sales_services.confirm_sales_bill(bill)
    assert bill.state == "confirmed"
    assert Notification.objects.filter(
        tenant=tenant, title__contains="信用额度即将用尽"
    ).count() == 1


def test_no_limit_no_check(tenant, warehouse, product):
    """credit_limit=0 表示不启用管控。"""
    c = baker.make(Customer, tenant=tenant, code="C002", name="不限客户",
                   credit_limit=Decimal("0"))
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=c, warehouse=warehouse,
        lines=[{"product": product, "quantity": 10, "unit_price": 100}],  # 1000 无额度
    )
    sales_services.confirm_sales_bill(bill)
    assert bill.state == "confirmed"


def test_rounded_bill_counts_net_amount(tenant, warehouse, customer, product):
    """抹零后按净额计入占用：旧账 44 + 行合计 1000.56 抹零后 1000 = 1044 ≤ 1000？不，
    这里验证"净额而非毛额"计入：旧账 600 + 1000.56→1000 = 1600 > 1000 必须拒绝；
    若按毛额计入 600+1000.56 更超。改用不超限场景：旧账 0 + 999 抹零… 直接验证
    旧账 44 + 1000.56 抹成 1000 = 1044 超限 → 用 force 之外，改为验证边界：
    旧账 0.56，本单 1000.56 抹到 1000，合计 1000.56 → 超 1000 拒绝；
    再把旧账清 0.44（收 0.12）后合计 1000.00 恰好通过。
    """
    from decimal import Decimal as D
    recv = _make_receivable(tenant, customer, 1)
    _stock_in(tenant, warehouse, product, 10)
    bill = sales_services.create_sales_bill(
        tenant=tenant, customer=customer, warehouse=warehouse,
        lines=[{"product": product, "quantity": 10, "unit_price": 100.05}],
        round_to="1",
    )
    # 10×100.05 = 1000.5 → 抹到 1000
    assert bill.total_amount == D("1000")
    assert bill.round_off == D("0.5")
    # outstanding = 1 + 1000 = 1001 > 1000 → 拒绝
    with pytest.raises(CreditLimitExceeded):
        sales_services.confirm_sales_bill(bill)
    # 客户还掉 1 元旧账 → outstanding 1000 = 限额，恰好通过
    recv.paid_amount = D("1")
    recv.status = "paid"
    recv.save()
    sales_services.confirm_sales_bill(bill)
    assert bill.state == "confirmed"