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

from app.database.models import User
from app.schemas.user import UserCreate, UserUpdate


class UserService:
    @staticmethod
    def get_all_users(db: Session) -> List[User]:
        """获取所有用户"""
        return db.query(User).all()

    @staticmethod
    def get_user_by_id(db: Session, user_id: int) -> Optional[User]:
        """根据ID获取用户"""
        return db.query(User).filter(User.id == user_id).first()

    @staticmethod
    def create_user(db: Session, user_data: UserCreate) -> User:
        """创建新用户"""
        try:
            db_user = User(
                username=user_data.username,
                email=user_data.email,
                full_name=user_data.full_name
            )
            db.add(db_user)
            db.commit()
            db.refresh(db_user)
            return db_user
        except IntegrityError as e:
            db.rollback()
            error_msg = str(e.orig)
            if "username" in error_msg:
                raise HTTPException(status_code=409, detail="Username already exists")
            elif "email" in error_msg:
                raise HTTPException(status_code=409, detail="Email 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_user(db: Session, user_id: int, user_data: UserUpdate) -> Optional[User]:
        """更新用户信息"""
        try:
            db_user = db.query(User).filter(User.id == user_id).first()
            if not db_user:
                return None

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

            db.commit()
            db.refresh(db_user)
            return db_user
        except IntegrityError as e:
            db.rollback()
            error_msg = str(e.orig)
            if "username" in error_msg:
                raise HTTPException(status_code=409, detail="Username already exists")
            elif "email" in error_msg:
                raise HTTPException(status_code=409, detail="Email 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_user(db: Session, user_id: int) -> bool:
        """删除用户"""
        try:
            db_user = db.query(User).filter(User.id == user_id).first()
            if not db_user:
                return False

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


user_service = UserService()