"""
认证依赖：从JWT令牌获取当前用户
"""
from typing import Optional

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession

from database import get_async_db
from database.models import User
from services.auth_service import verify_token

# OAuth2密码流配置
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_async_db)
) -> User:
    """
    从JWT令牌获取当前用户
    
    Args:
        token: JWT访问令牌
        db: 数据库会话
        
    Returns:
        当前用户对象
        
    Raises:
        HTTPException: 如果令牌无效或用户不存在
    """
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="无法验证凭据",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    # 验证令牌
    payload = verify_token(token)
    if payload is None:
        raise credentials_exception
    
    # 获取用户ID
    user_id: str = payload.get("sub")
    if user_id is None:
        raise credentials_exception
    
    # 检查令牌类型
    token_type = payload.get("type")
    if token_type != "access":
        raise credentials_exception
    
    # 从数据库获取用户
    user = await db.get(User, user_id)
    if user is None:
        raise credentials_exception
    
    return user


async def get_optional_user(
    token: Optional[str] = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_async_db)
) -> Optional[User]:
    """
    可选用户（用于某些公开端点）
    
    Args:
        token: JWT访问令牌（可选）
        db: 数据库会话
        
    Returns:
        用户对象（如果提供了有效令牌），否则返回None
    """
    if token is None:
        return None
    
    try:
        return await get_current_user(token, db)
    except HTTPException:
        return None