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

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

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl=f"{settings.API_V1_STR}/auth/login"
)


def authenticate_user(db: Session, username: str, password: str) -> User | None:
    """Authenticate a user by username and password
    """
    user = db.query(User).filter(User.username == username).first()
    if not user:
        return None
    if not verify_password(password, user.hashed_password):
        return None
    return user


def get_current_user(
    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
) -> User:
    """Get the current user from the token
    """
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Invalid authentication credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=["HS256"]
        )
        token_data = TokenPayload(**payload)

        if token_data.sub is None:
            raise credentials_exception
    except JWTError as e:
        raise credentials_exception from e

    user = db.query(User).filter(User.id == token_data.sub).first()
    if user is None:
        raise credentials_exception
    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Inactive user"
        )
    return user