auth.py

from datetime import datetime, timedelta
from typing import Optional
import os # NEW: Import os

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

from . import models, schemas
from .database import get_db

# Configuration for password hashing
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# JWT Secret Key and Algorithm (IMPORTANT: Use a strong, random key in production)
# For development, you can generate one with: openssl rand -hex 32
SECRET_KEY = os.getenv("SECRET_KEY", "super-secret-default-key-please-change-me") # UPDATED: Load from environment variable
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# OAuth2PasswordBearer for token extraction from request headers
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

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

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

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

def get_user(db: Session, email: str):
    """Retrieves a user by email from the database."""
    return db.query(models.User).filter(models.User.email == email).first()

def get_user_by_id(db: Session, user_id: int):
    """Retrieves a user by ID from the database."""
    return db.query(models.User).filter(models.User.id == user_id).first()

async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
    """
    FastAPI dependency to get the current authenticated user from a JWT token.
    Raises HTTPException if the token is invalid or user not found.
    """
    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])
        email: str = payload.get("sub")
        if email is None:
            raise credentials_exception
        token_data = schemas.TokenData(email=email)
    except JWTError:
        raise credentials_exception
    user = get_user(db, email=token_data.email)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user: schemas.User = Depends(get_current_user)):
    """
    FastAPI dependency to get the current active authenticated user.
    Raises HTTPException if the user is inactive.
    """
    if not current_user.is_active:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Inactive user")
    return current_user