decompose structure

src/features/current/useCurrentEvents.ts

@@ -0,0 +1,32 @@
+import { useEffect, useState } from 'react';
+import { useQueryClient } from '@tanstack/react-query';
+import { getCurrentEventsUrl } from '../../entities/current/api';
+import type { CurrentEvent, CurrentResponse } from '../../entities/current/types';
+
+export function useCurrentEvents(edgeId: string): boolean {
+  const queryClient = useQueryClient();
+  const [connected, setConnected] = useState(false);
+
+  useEffect(() => {
+    if (!edgeId || typeof EventSource === 'undefined') {
+      setConnected(false);
+      return undefined;
+    }
+
+    const eventSource = new EventSource(getCurrentEventsUrl(edgeId));
+
+    eventSource.onopen = () => setConnected(true);
+    eventSource.onerror = () => setConnected(false);
+    eventSource.onmessage = (message) => {
+      const event = JSON.parse(message.data) as CurrentEvent;
+      queryClient.setQueryData<CurrentResponse>(['current', edgeId], event);
+    };
+
+    return () => {
+      eventSource.close();
+      setConnected(false);
+    };
+  }, [edgeId, queryClient]);
+
+  return connected;
+}