from datetime import datetime, timedelta
from typing import Any, Union

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from sqlalchemy.orm import Session

from app.core.config import settings
from app.db.session import get_db
from app.models.user import User
from app.schemas.token import TokenPayload

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = settings.SECRET_KEY
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = settings.ACCESS_TOKEN_EXPIRE_MINUTES

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"{settings.API_V1_STR}/auth/login")


def create_access_token(subject: Union[str, Any], expires_delta: timedelta = None) -> str:
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode = {"exp": expire, "sub": str(subject)}
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)


async def get_current_user(db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        token_data = TokenPayload(**payload)
        if token_data.sub is None:
            raise credentials_exception
    except JWTError as e:
        raise credentials_exception from e

    from app.crud import user as user_crud

    user = user_crud.get(db, id=token_data.sub)
    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user