"""
用户服务

处理用户相关的业务逻辑。
"""

from datetime import datetime, timezone

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.exceptions import (
    UserAlreadyExistsError,
    UserNotFoundError,
)
from app.core.security import hash_password
from app.models.user import User
from app.repositories.user import UserRepository
from app.schemas.user import UserCreate, UserUpdate


class UserService:
    """用户服务"""

    def __init__(self, session: AsyncSession):
        """
        初始化用户服务
        
        Args:
            session: 数据库会话
        """
        self.session = session
        self.user_repo = UserRepository(session)

    async def create_user(self, user_data: UserCreate) -> User:
        """
        创建新用户
        
        Args:
            user_data: 用户注册数据
            
        Returns:
            新创建的用户
            
        Raises:
            UserAlreadyExistsError: 用户名或邮箱已存在
        """
        # 检查用户名是否已存在
        if await self.user_repo.exists_by_username(user_data.username):
            raise UserAlreadyExistsError("用户名")

        # 检查邮箱是否已存在
        if user_data.email and await self.user_repo.exists_by_email(user_data.email):
            raise UserAlreadyExistsError("邮箱")

        # 创建用户
        user = await self.user_repo.create(
            username=user_data.username.lower(),
            email=user_data.email.lower() if user_data.email else None,
            nickname=user_data.nickname,
            hashed_password=hash_password(user_data.password),
        )

        await self.user_repo.commit()
        return user

    async def get_user_by_id(self, user_id: str) -> User:
        """
        通过 ID 获取用户
        
        Args:
            user_id: 用户 ID
            
        Returns:
            用户对象
            
        Raises:
            UserNotFoundError: 用户不存在
        """
        user = await self.user_repo.get_by_id(user_id)
        if not user:
            raise UserNotFoundError(user_id)
        return user

    async def get_user_by_username(self, username: str) -> User | None:
        """
        通过用户名获取用户
        
        Args:
            username: 用户名
            
        Returns:
            用户对象或 None
        """
        return await self.user_repo.get_by_username(username)

    async def update_user(
        self,
        user_id: str,
        update_data: UserUpdate,
    ) -> User:
        """
        更新用户信息
        
        Args:
            user_id: 用户 ID
            update_data: 更新数据
            
        Returns:
            更新后的用户
            
        Raises:
            UserNotFoundError: 用户不存在
            UserAlreadyExistsError: 邮箱已被使用
        """
        user = await self.get_user_by_id(user_id)

        # 检查邮箱是否被其他用户使用
        if update_data.email:
            existing_user = await self.user_repo.get_by_email(update_data.email)
            if existing_user and existing_user.id != user_id:
                raise UserAlreadyExistsError("邮箱")

        # 准备更新数据
        update_dict = update_data.model_dump(exclude_unset=True)
        if update_dict.get("email"):
            update_dict["email"] = update_dict["email"].lower()

        # 更新用户
        user = await self.user_repo.update(user, **update_dict)
        await self.user_repo.commit()
        return user

    async def update_last_login(self, user: User) -> None:
        """
        更新用户最后登录时间
        
        Args:
            user: 用户对象
        """
        await self.user_repo.update(
            user,
            last_login_at=datetime.now(timezone.utc),
        )
        await self.user_repo.commit()

    async def deactivate_user(self, user_id: str) -> User:
        """
        禁用用户账户
        
        Args:
            user_id: 用户 ID
            
        Returns:
            更新后的用户
        """
        user = await self.get_user_by_id(user_id)
        user = await self.user_repo.update(user, is_active=False)
        await self.user_repo.commit()
        return user

    async def activate_user(self, user_id: str) -> User:
        """
        激活用户账户
        
        Args:
            user_id: 用户 ID
            
        Returns:
            更新后的用户
        """
        user = await self.get_user_by_id(user_id)
        user = await self.user_repo.update(user, is_active=True)
        await self.user_repo.commit()
        return user