from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from models.database import get_db
from models.models import User
from .jwt_utils import decode_access_token
from .roles import can_manage_users, can_write, is_admin

bearer_scheme = HTTPBearer(auto_error=False)


async def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(bearer_scheme),
    db: AsyncSession = Depends(get_db),
) -> User:
    if not credentials or not credentials.credentials:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="未登录或令牌缺失")
    payload = decode_access_token(credentials.credentials)
    if not payload or not payload.get("sub"):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="登录已过期，请重新登录")
    try:
        user_id = int(payload["sub"])
    except (TypeError, ValueError):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="无效令牌")

    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user or not user.is_active:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="用户不存在或已禁用")
    return user


async def require_admin(user: User = Depends(get_current_user)) -> User:
    if not is_admin(user.role):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="需要管理员权限")
    return user


async def require_write(user: User = Depends(get_current_user)) -> User:
    if not can_write(user.role):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="当前角色只读，无法执行此操作")
    return user


async def require_user_manager(user: User = Depends(get_current_user)) -> User:
    if not can_manage_users(user.role):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="需要管理员权限")
    return user