LabelingSystem/backend/services/jwt_service.py

"""
JWT Service for token generation and validation.
Handles creation and verification of access and refresh tokens.
"""
from datetime import datetime, timedelta
from typing import Dict, Optional
import jwt
from config import settings


class JWTService:
    """Service for JWT token operations."""
    
    @staticmethod
    def create_access_token(user_data: Dict) -> str:
        """
        Create access token with 15 minutes expiration.
        
        Args:
            user_data: Dict containing user_id, username, email, role
            
        Returns:
            Encoded JWT token string
        """
        expire = datetime.utcnow() + timedelta(
            minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
        )
        payload = {
            "sub": user_data["id"],
            "username": user_data["username"],
            "email": user_data["email"],
            "role": user_data["role"],
            "exp": expire,
            "iat": datetime.utcnow(),
            "type": "access"
        }
        return jwt.encode(
            payload,
            settings.JWT_SECRET_KEY,
            algorithm=settings.JWT_ALGORITHM
        )
    
    @staticmethod
    def create_refresh_token(user_data: Dict) -> str:
        """
        Create refresh token with 7 days expiration.
        
        Args:
            user_data: Dict containing user_id
            
        Returns:
            Encoded JWT token string
        """
        expire = datetime.utcnow() + timedelta(
            days=settings.REFRESH_TOKEN_EXPIRE_DAYS
        )
        payload = {
            "sub": user_data["id"],
            "exp": expire,
            "iat": datetime.utcnow(),
            "type": "refresh"
        }
        return jwt.encode(
            payload,
            settings.JWT_SECRET_KEY,
            algorithm=settings.JWT_ALGORITHM
        )
    
    @staticmethod
    def verify_token(token: str, token_type: str = "access") -> Optional[Dict]:
        """
        Verify and decode JWT token.
        
        Args:
            token: JWT token string
            token_type: Expected token type (access or refresh)
            
        Returns:
            Decoded payload dict or None if invalid
            
        Raises:
            jwt.ExpiredSignatureError: Token has expired
            jwt.InvalidTokenError: Token is invalid
        """
        try:
            payload = jwt.decode(
                token,
                settings.JWT_SECRET_KEY,
                algorithms=[settings.JWT_ALGORITHM]
            )
            
            # Verify token type
            if payload.get("type") != token_type:
                return None
                
            return payload
        except jwt.ExpiredSignatureError:
            raise
        except jwt.InvalidTokenError:
            raise