from typing import Generator

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

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


def get_db() -> Generator:
    """
    Dependency for getting a database session.
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def get_current_user(
    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
) -> User:
    """
    Validate the access token and return the current user.
    """
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
        )
        token_data = TokenPayload(**payload)
    except (JWTError, ValidationError):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Could not validate credentials",
        )
    
    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"
        )
    
    return user


def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    """
    Check if the current user is active.
    """
    if not current_user.is_active:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST, detail="Inactive user"
        )
    
    return current_user