"""采购需求推导集成测试

覆盖 P4-4 新功能：POST /api/purchase-demands/calculate
- 正常推导（有 BOM、有库存、有供应商）
- 库存不足时的缺口计算
- 无效销售订单 → 404
- 成品无 BOM → 空结果
- 空 sales_order_ids → 422
"""
import pytest


async def _get_inventory_id(client, sku: str) -> int:
    """从分页 API 获取库存记录 ID"""
    resp = await client.get("/api/inventory")
    items = resp.json()["items"]
    return next(r["id"] for r in items if r["product_sku"] == sku)


@pytest.mark.anyio
async def test_purchase_demand_basic_no_shortage(client):
    """库存充足时：需求量正确计算，缺口为 0"""
    # 创建销售订单：1 套标准模具（自动发料 3 单位，库存从 1000 → 997）
    so_resp = await client.post("/api/sales-orders", json={
        "customer_id": 1,
        "items": [{"product_id": 2, "quantity": 1, "unit_price": 1000.0}],
    })
    assert so_resp.status_code == 201, so_resp.text
    so_id = so_resp.json()["id"]

    # 重置库存为 1000（覆盖发料消耗）
    inv_id = await _get_inventory_id(client, "MAT-001")
    await client.put(f"/api/inventory/{inv_id}", json={
        "quantity": 1000, "locked_quantity": 0,
    })

    # 调用采购需求推导
    resp = await client.post("/api/purchase-demands/calculate", json={
        "sales_order_ids": [so_id],
    })
    assert resp.status_code == 200
    data = resp.json()

    assert data["source_order_ids"] == [so_id]
    assert len(data["source_order_nos"]) == 1
    assert len(data["items"]) == 1

    item = data["items"][0]
    assert item["material_sku"] == "MAT-001"
    # BOM: qty=2, loss_rate=0.05 → ceil(1*2*1.05) = ceil(2.1) = 3
    # Decimal 在 JSON 中可能序列化为字符串，用 int() 转换
    assert int(item["required_quantity"]) == 3
    # 库存 1000 > 需求 3，无缺口
    assert int(item["shortage_quantity"]) == 0
    assert float(item["estimated_cost"]) == 0
    # 推荐供应商（seeded_db 中 MaterialSupplier is_primary=True, lead_time=7）
    assert item["suggested_supplier_name"] == "供应商A"
    assert item["supplier_lead_time"] == 7


@pytest.mark.anyio
async def test_purchase_demand_with_shortage(client):
    """库存不足时：缺口 = 需求 - 库存，预计金额 = 缺口 × 单价"""
    # 创建销售订单：1 套标准模具（自动发料 3 单位，库存从 1000 → 997）
    so_resp = await client.post("/api/sales-orders", json={
        "customer_id": 1,
        "items": [{"product_id": 2, "quantity": 1, "unit_price": 1000.0}],
    })
    assert so_resp.status_code == 201, so_resp.text
    so_id = so_resp.json()["id"]

    # 将库存设为 0（完全缺货）
    inv_id = await _get_inventory_id(client, "MAT-001")
    await client.put(f"/api/inventory/{inv_id}", json={
        "quantity": 0, "locked_quantity": 0,
    })

    # 调用采购需求推导
    resp = await client.post("/api/purchase-demands/calculate", json={
        "sales_order_ids": [so_id],
    })
    assert resp.status_code == 200
    data = resp.json()

    item = data["items"][0]
    # BOM: qty=2, loss_rate=0.05 → ceil(1*2*1.05) = ceil(2.1) = 3
    assert int(item["required_quantity"]) == 3
    # 库存 0
    assert int(item["available_quantity"]) == 0
    # 缺口 = 3 - 0 = 3
    assert int(item["shortage_quantity"]) == 3
    # 预计金额 = 3 × 10.0 = 30.0
    assert float(item["estimated_cost"]) == 30.0
    assert float(data["total_estimated_cost"]) == 30.0
    assert data["shortage_count"] == 1


@pytest.mark.anyio
async def test_purchase_demand_invalid_order_ids(client):
    """不存在的销售订单 ID → 404"""
    resp = await client.post("/api/purchase-demands/calculate", json={
        "sales_order_ids": [99999],
    })
    assert resp.status_code == 404


@pytest.mark.anyio
async def test_purchase_demand_no_bom_returns_empty(client):
    """成品无 BOM 关联时，推导结果为空"""
    # product_id=3 是无 BOM 的成品（MOLD-NB）
    so_resp = await client.post("/api/sales-orders", json={
        "customer_id": 1,
        "items": [{"product_id": 3, "quantity": 1, "unit_price": 500.0}],
    })
    assert so_resp.status_code == 201, so_resp.text
    so_id = so_resp.json()["id"]

    resp = await client.post("/api/purchase-demands/calculate", json={
        "sales_order_ids": [so_id],
    })
    assert resp.status_code == 200
    data = resp.json()
    assert data["items"] == []
    assert float(data["total_estimated_cost"]) == 0
    assert data["shortage_count"] == 0


@pytest.mark.anyio
async def test_purchase_demand_empty_request_validation(client):
    """空 sales_order_ids 列表 → 422 schema 校验失败"""
    resp = await client.post("/api/purchase-demands/calculate", json={
        "sales_order_ids": [],
    })
    assert resp.status_code == 422