mybeacon-backend/backend/app/core/security.py

"""
Security utilities: JWT tokens, password hashing.
"""

from datetime import datetime, timedelta, timezone
from typing import Any

import bcrypt
from jose import JWTError, jwt

from app.config import settings


def create_access_token(data: dict[str, Any]) -> str:
    """
    Create JWT access token.

    Args:
        data: Payload to encode (typically {"sub": user_id})

    Returns:
        Encoded JWT token string
    """
    to_encode = data.copy()
    # Convert sub to string if it's an int (JWT standard requires string)
    if "sub" in to_encode and isinstance(to_encode["sub"], int):
        to_encode["sub"] = str(to_encode["sub"])
    expire = datetime.now(timezone.utc) + timedelta(
        minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
    )
    # Don't override type if already provided (e.g., "device" token)
    if "type" not in to_encode:
        to_encode["type"] = "access"
    to_encode["exp"] = expire
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def create_refresh_token(data: dict[str, Any]) -> str:
    """
    Create JWT refresh token.

    Args:
        data: Payload to encode (typically {"sub": user_id})

    Returns:
        Encoded JWT token string
    """
    to_encode = data.copy()
    # Convert sub to string if it's an int (JWT standard requires string)
    if "sub" in to_encode and isinstance(to_encode["sub"], int):
        to_encode["sub"] = str(to_encode["sub"])
    expire = datetime.now(timezone.utc) + timedelta(
        days=settings.REFRESH_TOKEN_EXPIRE_DAYS
    )
    to_encode.update({"exp": expire, "type": "refresh"})
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def verify_token(token: str, expected_type: str | None = "access") -> dict[str, Any] | None:
    """
    Verify and decode JWT token.

    Args:
        token: JWT token string
        expected_type: Expected token type ("access", "refresh", "device", etc.) or None to skip type check

    Returns:
        Decoded payload if valid, None otherwise
    """
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        # Only check type if expected_type is specified
        if expected_type is not None:
            token_type: str = payload.get("type")
            if token_type != expected_type:
                return None
        return payload
    except JWTError:
        return None


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """
    Verify a plain password against a hashed password.

    Args:
        plain_password: Plain text password
        hashed_password: Hashed password from database

    Returns:
        True if password matches, False otherwise
    """
    return bcrypt.checkpw(
        plain_password.encode("utf-8"), hashed_password.encode("utf-8")
    )


def hash_password(password: str) -> str:
    """
    Hash a password using bcrypt.

    Args:
        password: Plain text password

    Returns:
        Hashed password
    """
    salt = bcrypt.gensalt()
    hashed = bcrypt.hashpw(password.encode("utf-8"), salt)
    return hashed.decode("utf-8")