"""
购物车模型
"""
from datetime import datetime
from config.database import db
from app.models.product import Product, ProductInventory


class Cart(db.Model):
    """购物车模型"""
    __tablename__ = 'cart'

    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    product_id = db.Column(db.Integer, db.ForeignKey('products.id'), nullable=False)
    sku_code = db.Column(db.String(100))
    spec_combination = db.Column(db.String(255))
    quantity = db.Column(db.Integer, nullable=False, default=1)
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    # 关联关系
    user = db.relationship('User', backref='cart_items')
    product = db.relationship('Product', backref='cart_items')

    def get_sku_info(self):
        """获取SKU信息"""
        if self.sku_code:
            return ProductInventory.query.filter_by(sku_code=self.sku_code).first()
        else:
            # 如果没有SKU，返回默认库存信息
            return ProductInventory.query.filter_by(
                product_id=self.product_id,
                is_default=1
            ).first()

    def get_price(self):
        """获取商品价格"""
        sku_info = self.get_sku_info()
        if sku_info:
            return sku_info.get_final_price()
        return float(self.product.price) if self.product and self.product.price else 0

    def get_total_price(self):
        """获取小计金额"""
        return self.get_price() * self.quantity

    def get_stock(self):
        """获取库存数量"""
        sku_info = self.get_sku_info()
        return sku_info.stock if sku_info else 0

    def is_available(self):
        """检查商品是否可用"""
        # 检查商品是否上架
        if not self.product or self.product.status != 1:
            return False

        # 检查库存
        if self.get_stock() < self.quantity:
            return False

        return True

    def to_dict(self):
        """转换为字典"""
        sku_info = self.get_sku_info()
        return {
            'id': self.id,
            'user_id': self.user_id,
            'product_id': self.product_id,
            'product_name': self.product.name if self.product else '',
            'product_image': self.product.main_image if self.product else '',
            'brand': self.product.brand if self.product else '',
            'sku_code': self.sku_code,
            'spec_combination': self.spec_combination,
            'quantity': self.quantity,
            'price': self.get_price(),
            'total_price': self.get_total_price(),
            'stock': self.get_stock(),
            'is_available': self.is_available(),
            'created_at': self.created_at.isoformat() if self.created_at else None
        }

    @classmethod
    def add_to_cart(cls, user_id, product_id, sku_code=None, spec_combination=None, quantity=1):
        """添加商品到购物车"""
        # 检查是否已存在相同商品
        existing_item = cls.query.filter_by(
            user_id=user_id,
            product_id=product_id,
            sku_code=sku_code
        ).first()

        if existing_item:
            # 更新数量
            existing_item.quantity += quantity
            existing_item.updated_at = datetime.utcnow()
            db.session.commit()
            return existing_item
        else:
            # 创建新记录
            cart_item = cls(
                user_id=user_id,
                product_id=product_id,
                sku_code=sku_code,
                spec_combination=spec_combination,
                quantity=quantity
            )
            db.session.add(cart_item)
            db.session.commit()
            return cart_item

    @classmethod
    def get_user_cart(cls, user_id):
        """获取用户购物车"""
        return cls.query.filter_by(user_id=user_id)\
            .order_by(cls.created_at.desc()).all()

    @classmethod
    def get_cart_count(cls, user_id):
        """获取购物车商品数量"""
        return cls.query.filter_by(user_id=user_id).count()

    @classmethod
    def get_cart_total(cls, user_id):
        """获取购物车总金额"""
        cart_items = cls.get_user_cart(user_id)
        total = 0
        for item in cart_items:
            if item.is_available():
                total += item.get_total_price()
        return total

    def __repr__(self):
        return f'<Cart {self.user_id}-{self.product_id}>'