leocrm/app/core/ws_helpers.py

"""Shared WebSocket helpers: auth, origin check, tenant check, cleanup, heartbeat, error handling, message dispatch."""

from __future__ import annotations

import asyncio
import json
import logging
import uuid
from typing import Any, Callable

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from starlette.websockets import WebSocket

from app.core.auth import get_redis, get_session_data, verify_ws_origin
from app.config import get_settings

logger = logging.getLogger(__name__)


async def authenticate_ws(websocket: WebSocket, db: AsyncSession) -> dict[str, Any] | None:
    """Authenticate a WebSocket connection via session cookie.

    Extracts the session cookie, validates the session in Redis,
    and returns user/tenant info.  On failure, closes the WebSocket
    with code 4401 and returns ``None``.
    """
    settings = get_settings()
    session_id = websocket.cookies.get(settings.session_cookie_name)
    if not session_id:
        await websocket.close(code=4401, reason="Unauthorized")
        return None

    redis = get_redis()
    session_data = await get_session_data(redis, session_id)
    if session_data is None:
        await websocket.close(code=4401, reason="Unauthorized")
        return None

    if not session_data.get("is_active", False):
        await websocket.close(code=4401, reason="Unauthorized")
        return None

    return {
        "user_id": session_data["user_id"],
        "tenant_id": session_data["tenant_id"],
        "session_id": session_id,
        "role": session_data.get("role"),
        "email": session_data.get("email"),
        "name": session_data.get("name"),
        "is_system_admin": session_data.get("is_system_admin", False),
    }


async def check_ws_origin(websocket: WebSocket) -> bool:
    """Verify the WebSocket origin and CSRF token.

    Delegates to :func:`verify_ws_origin`.  On failure, closes the
    WebSocket with code 4403 and returns ``False``.
    """
    result = await verify_ws_origin(websocket)
    if not result:
        await websocket.close(code=4403, reason="Forbidden origin")
        return False
    return True


async def check_ws_tenant(
    websocket: WebSocket,
    tenant_id: uuid.UUID,
    user_id: uuid.UUID,
    db: AsyncSession,
) -> bool:
    """Verify that *user_id* belongs to *tenant_id*.

    On failure, closes the WebSocket with code 4403 and returns ``False``.
    """
    from app.models.user import UserTenant

    result = await db.execute(
        select(UserTenant).where(
            UserTenant.user_id == user_id,
            UserTenant.tenant_id == tenant_id,
        )
    )
    if result.scalar_one_or_none() is None:
        await websocket.close(code=4403, reason="Forbidden tenant")
        return False
    return True


async def cleanup_ws_connection(
    websocket: WebSocket,
    user_id: str,
    connection_registry: dict[str, list[WebSocket]],
) -> None:
    """Remove a WebSocket from the connection registry and close it cleanly."""
    conns = connection_registry.get(user_id, [])
    if websocket in conns:
        conns.remove(websocket)
    if not conns:
        connection_registry.pop(user_id, None)
    try:
        await websocket.close()
    except Exception:
        logger.debug("WebSocket already closed during cleanup for user %s", user_id)


async def start_heartbeat(websocket: WebSocket, interval: int = 30) -> asyncio.Task:
    """Start a background heartbeat task that sends periodic pings.

    Returns the :class:`asyncio.Task` so the caller can cancel it on disconnect.
    """

    async def _heartbeat() -> None:
        while True:
            try:
                await asyncio.sleep(interval)
                await websocket.send_text(json.dumps({"type": "ping"}))
            except asyncio.CancelledError:
                break
            except Exception:
                logger.debug("Heartbeat stopped — WebSocket likely closed")
                break

    return asyncio.create_task(_heartbeat())


async def send_ws_error(
    websocket: WebSocket,
    code: str,
    detail: str,
    trace_id: str | None = None,
) -> None:
    """Send a structured error message to the WebSocket client."""
    payload: dict[str, Any] = {
        "type": "error",
        "code": code,
        "detail": detail,
    }
    if trace_id is not None:
        payload["trace_id"] = trace_id
    try:
        await websocket.send_text(json.dumps(payload, default=str))
    except Exception:
        logger.debug("Failed to send WS error to client")


async def handle_ws_message(
    websocket: WebSocket,
    message: str,
    handlers: dict[str, Callable[[WebSocket, dict[str, Any]], Any]],
) -> None:
    """Dispatch a WebSocket text message to the appropriate handler.

    *handlers* maps message ``type`` strings to async callables that accept
    ``(websocket, msg)``.  Unknown types and handler exceptions are
    reported back to the client via :func:`send_ws_error`.
    """
    try:
        msg = json.loads(message)
    except (json.JSONDecodeError, TypeError):
        await send_ws_error(websocket, "invalid_json", "Message is not valid JSON")
        return

    if not isinstance(msg, dict):
        await send_ws_error(websocket, "invalid_message", "Message must be a JSON object")
        return

    msg_type = msg.get("type")
    if not msg_type:
        await send_ws_error(websocket, "missing_type", "Message missing 'type' field")
        return

    handler = handlers.get(msg_type)
    if handler is None:
        await send_ws_error(websocket, "unknown_type", f"Unknown message type: {msg_type}")
        return

    try:
        await handler(websocket, msg)
    except Exception as exc:
        logger.exception("Handler error for message type '%s'", msg_type)
        await send_ws_error(websocket, "handler_error", str(exc))