"""purchase 序列化器（async 兼容）。"""

from rest_framework import serializers
from apps.core.serializers import AsyncModelSerializer
from .models import PurchaseOrder, PurchaseOrderLine, PurchaseBill, PurchaseBillLine


class PurchaseOrderLineSerializer(AsyncModelSerializer):
    product_code = serializers.CharField(source="product.code", read_only=True)
    product_name = serializers.CharField(source="product.name", read_only=True)

    class Meta:
        model = PurchaseOrderLine
        fields = ["id", "product", "product_code", "product_name",
                  "quantity", "unit_price", "amount", "received_qty"]
        read_only_fields = ["id", "amount", "received_qty"]


class PurchaseOrderSerializer(AsyncModelSerializer):
    supplier_code = serializers.CharField(source="supplier.code", read_only=True)
    warehouse_code = serializers.CharField(source="warehouse.code", read_only=True)
    lines = PurchaseOrderLineSerializer(many=True, required=False)

    class Meta:
        model = PurchaseOrder
        fields = [
            "id", "bill_no", "supplier", "supplier_code",
            "warehouse", "warehouse_code",
            "bill_date", "expected_date", "total_amount", "state", "remark",
            "lines",
        ]
        read_only_fields = ["id", "bill_no", "total_amount", "state"]

    def create(self, validated_data):
        lines = validated_data.pop("lines", [])
        tenant = self.context["request"]._request.tenant if hasattr(self.context.get("request", None), "_request") else None
        # 多租户注入由 acreate 处理（参考 catalog）
        from django.db import transaction
        from datetime import date

        with transaction.atomic():
            order = PurchaseOrder.objects.create(**validated_data)
            total = Decimal = __import__("decimal").Decimal
            tot = total("0")
            for ln in lines:
                qty = total(str(ln["quantity"]))
                price = total(str(ln["unit_price"]))
                PurchaseOrderLine.objects.create(
                    tenant=order.tenant,
                    order=order,
                    product=ln["product"],
                    quantity=qty,
                    unit_price=price,
                    amount=qty * price,
                )
                tot += qty * price
            order.total_amount = tot
            order.save(update_fields=["total_amount"])
        return order


class PurchaseBillLineSerializer(AsyncModelSerializer):
    product_code = serializers.CharField(source="product.code", read_only=True)
    product_name = serializers.CharField(source="product.name", read_only=True)
    unit_name = serializers.SerializerMethodField()
    is_batch_managed = serializers.BooleanField(
        source="product.is_batch_managed", read_only=True
    )

    class Meta:
        model = PurchaseBillLine
        fields = ["id", "product", "product_code", "product_name",
                  "quantity", "source_unit", "source_quantity", "unit_name",
                  "unit_price", "amount", "tax_rate", "tax_amount",
                  "batch_no", "production_date", "expiry_date", "is_batch_managed"]
        read_only_fields = ["id", "amount"]

    def get_unit_name(self, obj):
        unit = obj.source_unit or getattr(obj.product, "base_unit", None)
        return unit.name if unit else ""


class PurchaseBillSerializer(AsyncModelSerializer):
    supplier_code = serializers.CharField(source="supplier.code", read_only=True)
    supplier_name = serializers.CharField(source="supplier.name", read_only=True)
    warehouse_code = serializers.CharField(source="warehouse.code", read_only=True)
    lines = PurchaseBillLineSerializer(many=True, required=False)

    class Meta:
        model = PurchaseBill
        fields = [
            "id", "bill_no", "supplier", "supplier_code", "supplier_name",
            "warehouse", "warehouse_code", "order",
            "bill_date", "total_amount", "state", "remark",
            "lines",
        ]
        read_only_fields = ["id", "bill_no", "total_amount", "state"]