gateway/modules/security/auth.py

"""
Authentication module for backend API.
Handles JWT-based authentication, token generation, and user context.
"""

from datetime import datetime, timedelta, timezone
import uuid
from typing import Optional, Dict, Any, Tuple
from fastapi import Depends, HTTPException, status, Request
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
import logging
from slowapi import Limiter
from slowapi.util import get_remote_address

from modules.shared.configuration import APP_CONFIG
from modules.shared.timezoneUtils import get_utc_now, get_utc_timestamp
from modules.interfaces.interfaceAppObjects import getRootInterface
from modules.interfaces.interfaceAppModel import User, AuthAuthority, Token

# Get Config Data
SECRET_KEY = APP_CONFIG.get("APP_JWT_KEY_SECRET")
ALGORITHM = APP_CONFIG.get("Auth_ALGORITHM")
ACCESS_TOKEN_EXPIRE_MINUTES = int(APP_CONFIG.get("APP_TOKEN_EXPIRY"))
REFRESH_TOKEN_EXPIRE_DAYS = int(APP_CONFIG.get("APP_REFRESH_TOKEN_EXPIRY", "7"))

# OAuth2 Setup
oauth2Scheme = OAuth2PasswordBearer(tokenUrl="token")

# Rate Limiter
limiter = Limiter(key_func=get_remote_address)

# Logger
logger = logging.getLogger(__name__)

def createAccessToken(data: dict, expiresDelta: Optional[timedelta] = None) -> Tuple[str, datetime]:
    """
    Creates a JWT Access Token.
    
    Args:
        data: Data to encode (usually user ID or username)
        expiresDelta: Validity duration of the token (optional)
        
    Returns:
        Tuple of (JWT Token as string, expiration datetime)
    """
    toEncode = data.copy()
    # Ensure a token id (jti) exists for revocation tracking (only required for local, harmless otherwise)
    if "jti" not in toEncode or not toEncode.get("jti"):
        toEncode["jti"] = str(uuid.uuid4())
    
    if expiresDelta:
        expire = get_utc_now() + expiresDelta
    else:
        expire = get_utc_now() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
        
    toEncode.update({"exp": expire})
    encodedJwt = jwt.encode(toEncode, SECRET_KEY, algorithm=ALGORITHM)
    
    return encodedJwt, expire

def _getUserBase(token: str = Depends(oauth2Scheme)) -> User:
    """
    Extracts and validates the current user from the JWT token.
    
    Args:
        token: JWT Token from the Authorization header
        
    Returns:
        User model instance
        
    Raises:
        HTTPException: For invalid token or user
    """
    credentialsException = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Invalid authentication credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    try:
        # Decode token
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        
        # Extract username from token
        username: str = payload.get("sub")
        if username is None:
            raise credentialsException
            
        # Extract mandate ID and user ID from token
        mandateId: str = payload.get("mandateId")
        userId: str = payload.get("userId")
        authority: str = payload.get("authenticationAuthority")
        tokenId: Optional[str] = payload.get("jti")
        sessionId: Optional[str] = payload.get("sid") or payload.get("sessionId")
        
        if not mandateId or not userId:
            logger.error(f"Missing context in token: mandateId={mandateId}, userId={userId}")
            raise credentialsException
        
    except JWTError:
        logger.warning("Invalid JWT Token")
        raise credentialsException
    
    # Initialize Gateway Interface with context
    appInterface = getRootInterface()
    
    # Retrieve user from database
    user = appInterface.getUserByUsername(username)
    
    if user is None:
        logger.warning(f"User {username} not found")
        raise credentialsException
        
    # Check if user is enabled
    if not user.enabled:
        logger.warning(f"User {username} is disabled")
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="User is disabled")
    
    # Ensure the user has the correct context
    if str(user.mandateId) != str(mandateId) or str(user.id) != str(userId):
        logger.error(f"User context mismatch: token(mandateId={mandateId}, userId={userId}) vs user(mandateId={user.mandateId}, id={user.id})")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User context has changed. Please log in again.",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # For LOCAL gateway JWTs, enforce DB-backed token validity and revocation
    try:
        # Normalize authority to string for comparison
        normalized_authority = (str(authority).lower() if authority is not None else None)

        # If we have a token id, check if a corresponding DB token exists for local authority
        db_tokens = []
        if tokenId:
            try:
                db_tokens = appInterface.db.getRecordset(
                    Token, recordFilter={"id": tokenId}
                )
            except Exception:
                db_tokens = []

        if db_tokens:
            # There is a server record for this token; enforce status and context when local
            db_token = db_tokens[0]
            token_authority = str(db_token.get("authority", "")).lower()
            if token_authority == str(AuthAuthority.LOCAL.value):
                # Must be active and match user/session/mandate
                active_token = appInterface.findActiveTokenById(
                    tokenId=tokenId,
                    userId=user.id,
                    authority=AuthAuthority.LOCAL,
                    sessionId=sessionId,
                    mandateId=str(mandateId) if mandateId else None,
                )
                if not active_token:
                    logger.info(
                        f"Local JWT db record not active/valid: jti={tokenId}, userId={user.id}, mandateId={mandateId}, sessionId={sessionId}"
                    )
                    raise credentialsException
        else:
            # No DB record for this token. If the claim says local (or missing/unknown), require DB record.
            if normalized_authority in (None, "", str(AuthAuthority.LOCAL.value)):
                logger.info("Local JWT without server record or missing authority claim")
                raise credentialsException
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error during local token validation: {str(e)}")
        raise credentialsException
    
    return user

def getCurrentUser(currentUser: User = Depends(_getUserBase)) -> User:
    """Get current active user with additional validation."""
    # Check if current user is enabled
    if not currentUser.enabled:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="User is disabled"
        )
    return currentUser