from typing import Optional

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from pydantic import ValidationError
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 token URL
oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl=f"{settings.API_V1_STR}/auth/login"
)


def get_current_user(
    db: Session = Depends(get_db),
    token: str = Depends(oauth2_scheme)
) -> User:
    """
    Get current user from token
    """
    try:
        # Decode the token
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
        )
        token_data = TokenPayload(**payload)
    except (JWTError, ValidationError):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Get user from database
    user = db.query(User).filter(User.id == token_data.sub).first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Inactive user"
        )

    return user


def get_current_active_superuser(
    current_user: User = Depends(get_current_user),
) -> User:
    """
    Get current superuser
    """
    if not current_user.is_superuser:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="The user doesn't have enough privileges"
        )

    return current_user


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

    return user