app/deps.py

"""Provide FastAPI dependencies for protected routes.

Session validity is checked against expiry and durable session version.
"""

import time
from typing import Any

from fastapi import HTTPException, Request, status

from app.models import StoredConfig


def api_http_error(status_code: int, code: str, message: str) -> HTTPException:
    """Create an HTTP exception understood by the envelope handler."""

    return HTTPException(
        status_code=status_code,
        detail={"code": code, "message": message},
    )


def require_login(request: Request) -> StoredConfig:
    """Require a current signed session and return durable config."""

    config: StoredConfig | None = request.app.state.config_store.load()
    if config is None:
        raise api_http_error(
            status.HTTP_503_SERVICE_UNAVAILABLE,
            "setup_required",
            "Application setup is required",
        )

    session: dict[str, Any] = request.session
    authenticated = session.get("auth") is True
    version_matches = session.get("sv") == config.session_version
    expiry = session.get("exp")
    unexpired = isinstance(expiry, (int, float)) and expiry >= time.time()
    if not (authenticated and version_matches and unexpired):
        request.session.clear()
        raise api_http_error(
            status.HTTP_401_UNAUTHORIZED,
            "unauthorized",
            "Login required",
        )
    return config