from typing import List, Optional
from sqlalchemy.orm import Session
from sqlalchemy.exc import IntegrityError
from fastapi import HTTPException

from app.database.models import Product
from app.schemas.product import ProductCreate, ProductUpdate


class ProductService:
    @staticmethod
    def get_all_products(db: Session) -> List[Product]:
        """获取所有产品"""
        return db.query(Product).all()

    @staticmethod
    def get_product_by_id(db: Session, product_id: int) -> Optional[Product]:
        """根据ID获取产品"""
        return db.query(Product).filter(Product.id == product_id).first()

    @staticmethod
    def create_product(db: Session, product_data: ProductCreate) -> Product:
        """创建新产品"""
        try:
            db_product = Product(
                name=product_data.name,
                description=product_data.description,
                price=product_data.price,
                stock=product_data.stock
            )
            db.add(db_product)
            db.commit()
            db.refresh(db_product)
            return db_product
        except IntegrityError as e:
            db.rollback()
            error_msg = str(e.orig)
            if "name" in error_msg:
                raise HTTPException(status_code=409, detail="Product name already exists")
            else:
                raise HTTPException(status_code=409, detail="Data conflict")
        except Exception as e:
            db.rollback()
            raise HTTPException(status_code=500, detail="Internal server error")

    @staticmethod
    def update_product(db: Session, product_id: int, product_data: ProductUpdate) -> Optional[Product]:
        """更新产品信息"""
        try:
            db_product = db.query(Product).filter(Product.id == product_id).first()
            if not db_product:
                return None

            update_data = product_data.model_dump(exclude_unset=True)
            for field, value in update_data.items():
                setattr(db_product, field, value)

            db.commit()
            db.refresh(db_product)
            return db_product
        except IntegrityError as e:
            db.rollback()
            error_msg = str(e.orig)
            if "name" in error_msg:
                raise HTTPException(status_code=409, detail="Product name already exists")
            else:
                raise HTTPException(status_code=409, detail="Data conflict")
        except Exception as e:
            db.rollback()
            raise HTTPException(status_code=500, detail="Internal server error")

    @staticmethod
    def delete_product(db: Session, product_id: int) -> bool:
        """删除产品"""
        try:
            db_product = db.query(Product).filter(Product.id == product_id).first()
            if not db_product:
                return False

            db.delete(db_product)
            db.commit()
            return True
        except Exception as e:
            db.rollback()
            raise HTTPException(status_code=500, detail="Internal server error")


product_service = ProductService()