from pytz import timezone

from typing import Optional
from datetime import datetime, timedelta

from fastapi.security import OAuth2PasswordBearer

import jwt

from core.configs import settings
from core.security import validate_pass, create_password_hash
from schemas.user_schema import UserSchema

oauth2_schema = OAuth2PasswordBearer(
    tokenUrl=f"{settings.API_V0_STR}/login"
)


async def authenticate(username: str, password: str) -> Optional[UserSchema]:
    if username != 'user':
        return None

    test_hash = create_password_hash('user1234')

    if not validate_pass(password, test_hash):
        return None

    # The returned value at this point should be UserModel, but since we do not have any persistence
    # and this is for demo purposes only
    return UserSchema(id=0, username='user', hash_pass=test_hash)

def _create_token(token_type: str, lifetime: timedelta, sub: str) -> str:
    # https://dataracker.ietf.org/doc/html/rfc7519#section-4.1.3
    payload = {}

    pt = timezone('UTC')
    expires = datetime.now(tz=pt) + lifetime

    payload["type"] = token_type

    payload["exp"] = expires

    payload["iat"] = datetime.now(tz=pt) #Issued-At (iat)

    payload["sub"] = str(sub)

    return jwt.encode(payload, settings.JWT_SECRET, algorithm=settings.ALGORITHM)


def create_access_token(sub: str) -> str:
    """
    https://jwt.io
    """
    return _create_token(
        token_type='access_token',
        lifetime=timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES),
        sub=sub
    )