"""
Shipment API 序列化器
"""
from rest_framework import serializers

from shipment.models import Shipment


class ShipmentSerializer(serializers.ModelSerializer):
    """
    出货单序列化器（只读，用于返回数据）
    """
    customer_name = serializers.CharField(source='customer.name', read_only=True)
    created_by_id = serializers.IntegerField(source='created_by.id', read_only=True, allow_null=True)
    created_by_name = serializers.SerializerMethodField()
    items_count = serializers.SerializerMethodField()
    
    class Meta:
        model = Shipment
        fields = [
            'id', 'customer', 'customer_name', 'shipment_date', 'remark',
            'items_count', 'created_by_id', 'created_by_name',
            'created_at', 'updated_at'
        ]
        read_only_fields = ['id', 'created_at', 'updated_at']
    
    def get_created_by_name(self, obj):
        if obj.created_by:
            employee = getattr(obj.created_by, 'employee', None)
            if employee:
                return employee.name
            return obj.created_by.username
        return None
    
    def get_items_count(self, obj):
        return obj.items.count()


class ShipmentCreateSerializer(serializers.Serializer):
    """
    出货单创建序列化器
    """
    customer = serializers.IntegerField(help_text='客户ID')
    shipment_date = serializers.DateField(help_text='出货日期')
    remark = serializers.CharField(required=False, default='', allow_blank=True, help_text='备注')
    sales_items = serializers.ListField(
        child=serializers.IntegerField(),
        required=False,
        default=list,
        help_text='要关联的销售品ID列表'
    )
    
    def validate_sales_items(self, value):
        # 去重
        return list(set(value)) if value else []


class SalesItemSerializer(serializers.Serializer):
    """
    销售品序列化器（只读）
    
    用于返回销售品数据
    """
    id = serializers.IntegerField(read_only=True)
    name = serializers.CharField(read_only=True)
    quantity = serializers.DecimalField(max_digits=12, decimal_places=2, read_only=True)
    unit = serializers.IntegerField(read_only=True)
    unit_display = serializers.SerializerMethodField()
    position = serializers.CharField(read_only=True)
    remark = serializers.CharField(read_only=True)
    printing_job_id = serializers.IntegerField(read_only=True)
    customer_id = serializers.IntegerField(read_only=True)
    shipment_id = serializers.IntegerField(source='shipment.id', read_only=True, allow_null=True)
    shipment_date = serializers.DateField(source='shipment.shipment_date', read_only=True, allow_null=True)
    created_at = serializers.DateTimeField(read_only=True)
    created_by_id = serializers.IntegerField(source='created_by.id', read_only=True, allow_null=True)
    created_by_name = serializers.SerializerMethodField()
    
    def get_unit_display(self, obj):
        return obj.get_unit_display()
    
    def get_created_by_name(self, obj):
        if obj.created_by:
            employee = getattr(obj.created_by, 'employee', None)
            if employee:
                return employee.name
            return obj.created_by.username
        return None