#!/usr/bin/env python
# -*- coding: utf-8 -*-

import json
from typing import Generator, Union, Optional

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

from core import security
from core.config import settings
from crud.user import crud_admin, crud_teacher, crud_student
from db.asyncsession import LocalAsyncSession
from models.user import Teacher, Student, SysUser
from schemas.auth import TokenPayload

reusable_oauth2 = OAuth2PasswordBearer(tokenUrl=f"/{settings.API_V1_STR}/login")


async def get_async_db() -> Generator:
    async with LocalAsyncSession() as db:
        yield db


def check_access_token(token: str):
    try:
        payload = jwt.decode(token,
                             settings.SECRET_KEY,
                             algorithms=[security.ALGORITHM])
        payload["sub"] = json.loads(payload["sub"])
        token_payload = TokenPayload(**payload)
    except (jwt.PyJWTError, ValidationError):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN,
                            detail="Invalid Access Token!!")
    return token_payload


async def get_current_user(token: str = Depends(reusable_oauth2),
                           db: AsyncSession = Depends(get_async_db)
                          ) -> Optional[Union[SysUser, Teacher, Student]]:
    token_payload = check_access_token(token)
    if token_payload.sub["utype"] == 0:
        crud = crud_admin
    elif token_payload.sub["utype"] == 1:
        crud = crud_teacher
    else:
        crud = crud_student
    user = await crud.find_one(db, {"username": token_payload.sub["sub"]})
    return user