# events/failure_stream.py

import asyncio
import json

class FailureStream:

    def __init__(self, ws_broadcaster, propagation_engine):
        self.ws = ws_broadcaster
        self.propagation = propagation_engine

    async def emit_failure(self, failed_node):

        map_result = self.propagation.map_failure(failed_node)

        payload = {
            "type": "failure_propagation",
            "data": map_result
        }

        await self.ws.broadcast(json.dumps(payload))