dchain/client-app/hooks/useContacts.ts

/**
 * Contacts + inbound request tracking.
 *
 * - Loads cached contacts from local storage on boot.
 * - Subscribes to the address WS topic so a new CONTACT_REQUEST pulls the
 *   relay contact list immediately (sub-second UX).
 * - Keeps a 30 s polling fallback for nodes without WS or while disconnected.
 */

import { useEffect, useCallback } from 'react';
import { fetchContactRequests } from '@/lib/api';
import { getWSClient } from '@/lib/ws';
import { loadContacts } from '@/lib/storage';
import { useStore } from '@/lib/store';

const FALLBACK_POLL_INTERVAL = 30_000;

export function useContacts() {
  const keyFile     = useStore(s => s.keyFile);
  const setContacts = useStore(s => s.setContacts);
  const setRequests = useStore(s => s.setRequests);
  const contacts    = useStore(s => s.contacts);

  // Load cached contacts from local storage once
  useEffect(() => {
    loadContacts().then(setContacts);
  }, [setContacts]);

  const pollRequests = useCallback(async () => {
    if (!keyFile) return;
    try {
      const raw = await fetchContactRequests(keyFile.pub_key);

      // Filter out already-accepted contacts
      const contactAddresses = new Set(contacts.map(c => c.address));

      const requests = raw
        .filter(r => r.status === 'pending' && !contactAddresses.has(r.requester_pub))
        .map(r => ({
          from:      r.requester_pub,
          // x25519Pub will be fetched from identity when user taps Accept
          x25519Pub: '',
          intro:     r.intro ?? '',
          timestamp: r.created_at,
          txHash:    r.tx_id,
        }));

      setRequests(requests);
    } catch {
      // Ignore transient network errors
    }
  }, [keyFile, contacts, setRequests]);

  useEffect(() => {
    if (!keyFile) return;
    const ws = getWSClient();

    // Initial load + low-frequency fallback poll (covers missed WS events,
    // works even when the node has no WS endpoint).
    pollRequests();
    const interval = setInterval(pollRequests, FALLBACK_POLL_INTERVAL);

    // Immediate refresh when a CONTACT_REQUEST / ACCEPT_CONTACT tx addressed
    // to us lands on-chain. WS fan-out already filters to our address topic.
    const off = ws.subscribe('addr:' + keyFile.pub_key, (frame) => {
      if (frame.event === 'tx') {
        const d = frame.data as { tx_type?: string } | undefined;
        if (d?.tx_type === 'CONTACT_REQUEST' || d?.tx_type === 'ACCEPT_CONTACT') {
          pollRequests();
        }
      }
    });
    ws.connect();

    return () => {
      clearInterval(interval);
      off();
    };
  }, [keyFile, pollRequests]);
}