from typing import Optional

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from pydantic import ValidationError
from sqlalchemy.orm import Session

from app.db.session import get_db
from app.core.config import settings
from app.core.security import ALGORITHM
from app.models.user import User
from app.schemas.user import TokenPayload
from app import crud

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/auth/login", auto_error=False)


def get_current_user(
    db: Session = Depends(get_db), token: Optional[str] = Depends(oauth2_scheme)
) -> Optional[User]:
    """
    Get the current user from the provided JWT token.
    Returns None if no token is provided or the token is invalid.
    """
    if not token:
        return None

    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[ALGORITHM])
        token_data = TokenPayload(**payload)
    except (JWTError, ValidationError):
        return None

    user = crud.user.get(db, id=token_data.sub)
    if not user:
        return None

    return user


def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    """
    Get the current active user and raise an exception if the user is not
    authenticated or inactive.
    """
    if not current_user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )

    if not crud.user.is_active(current_user):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN, detail="Inactive user"
        )

    return current_user