auth.py

from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
import os
from dotenv import load_dotenv

import models
import schemas
from database import get_db

load_dotenv()

# Password hashing
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# OAuth2 scheme
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="login")

# Environment variables
SECRET_KEY = os.getenv("SECRET_KEY")
ALGORITHM = os.getenv("ALGORITHM")
ACCESS_TOKEN_EXPIRE_MINUTES = int(os.getenv("ACCESS_TOKEN_EXPIRE_MINUTES"))


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a password against a hash"""
    return pwd_context.verify(plain_password, hashed_password)


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


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    """Create JWT access token"""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def authenticate_user(db: Session, username: str, password: str):
    """Authenticate user with username and password"""
    user = db.query(models.User).filter(models.User.username == username).first()
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
    """Get current authenticated 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])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = schemas.TokenData(username=username)
    except JWTError:
        raise credentials_exception
    
    user = db.query(models.User).filter(models.User.username == token_data.username).first()
    if user is None:
        raise credentials_exception
    
    return user


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