from typing import Union, Annotated

from fastapi import Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer, HTTPBearer, HTTPAuthorizationCredentials
from jose import jwt, JWTError
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from starlette import status

import backend.config
from backend.session import get_session
from models import User
from services.base import BaseService
from schemas.auth import *

oauth2_schema = HTTPBearer()
algorithm = 'HS256'


async def get_current_user(session: Annotated[AsyncSession, Depends(get_session)],
                           token: Annotated[HTTPAuthorizationCredentials, Depends(oauth2_schema)]) -> User | None:
    if not token.credentials:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail='Invalid token')
    try:
        payload = jwt.decode(token.credentials, backend.config.SECRET_KEY, algorithms=[algorithm])
        user_id = payload.get('sub')
        if not user_id:
            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail='Invalid credentials')
        user_id = int(user_id)

        user = await session.get(User, user_id)
        if not user:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail='Invalid credentials')
        return user
    except JWTError as e:
        print(e)
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail='Invalid token')


class AuthService(BaseService):
    @staticmethod
    def _generate_jwt_token(user: User) -> str:
        payload = {
            'sub': str(user.id)
        }
        return jwt.encode(payload, backend.config.SECRET_KEY, algorithm=algorithm)

    async def authenticate(self, request: AuthLoginRequest):
        user: Union[User, None] = await self.session.scalar(select(User).where(User.telegram_id == request.id))
        if not user:
            user = User(telegram_id=request.id,
                        is_admin=False)
            self.session.add(user)
            await self.session.commit()
        access_token = self._generate_jwt_token(user)
        return AuthLoginResponse(access_token=access_token)