"""inventory 序列化器（async 兼容）。"""

from rest_framework import serializers
from apps.core.serializers import AsyncModelSerializer
from .models import Warehouse, Stock, StockBatch, StockMovement


class WarehouseSerializer(AsyncModelSerializer):
    class Meta:
        model = Warehouse
        fields = [
            "id", "code", "name", "location", "is_active", "is_default",
            "is_deleted", "created_at", "updated_at",
        ]
        read_only_fields = ["id", "created_at", "updated_at"]


class StockSerializer(AsyncModelSerializer):
    warehouse_code = serializers.CharField(source="warehouse.code", read_only=True)
    product_code = serializers.CharField(source="product.code", read_only=True)
    product_name = serializers.CharField(source="product.name", read_only=True)
    available = serializers.SerializerMethodField()

    class Meta:
        model = Stock
        fields = [
            "id", "warehouse_code", "product_code", "product_name",
            "on_hand", "locked", "available", "avg_cost",
            "is_deleted", "created_at", "updated_at",
        ]
        read_only_fields = ["id", "created_at", "updated_at", "available", "on_hand", "locked", "avg_cost"]

    def get_available(self, obj):
        return str(obj.on_hand - obj.locked)


class StockMovementSerializer(AsyncModelSerializer):
    warehouse_code = serializers.CharField(source="warehouse.code", read_only=True)
    product_code = serializers.CharField(source="product.code", read_only=True)

    class Meta:
        model = StockMovement
        fields = [
            "id", "warehouse_code", "product_code",
            "movement_type", "source_type", "source_ref",
            "quantity", "unit_cost",
            "created_at",
        ]
        read_only_fields = fields  # 流水只读


class StockBatchSerializer(AsyncModelSerializer):
    warehouse_code = serializers.CharField(source="warehouse.code", read_only=True)
    product_code = serializers.CharField(source="product.code", read_only=True)
    product_name = serializers.CharField(source="product.name", read_only=True)
    available = serializers.SerializerMethodField()

    class Meta:
        model = StockBatch
        fields = [
            "id", "warehouse_code", "product_code", "product_name",
            "batch_no", "production_date", "expiry_date",
            "on_hand", "locked", "available", "unit_cost",
            "is_deleted", "created_at", "updated_at",
        ]
        read_only_fields = ["id", "created_at", "updated_at", "available"]

    def get_available(self, obj):
        return str(obj.on_hand - obj.locked)