// Small helper to resolve the Chat WebSocket URL from env or sensible defaults
export function getChatWsUrl() {
  // Prefer explicit env var
  const override = (typeof window !== 'undefined' && window.localStorage) ? window.localStorage.getItem('chatWsOverride') : '';
  if (override && typeof override === 'string' && override.trim()) {
    return override.trim();
  }
  const envUrl = import.meta?.env?.VITE_CHAT_WS_URL;
  if (envUrl && typeof envUrl === 'string' && envUrl.trim()) {
    return envUrl.trim();
  }
  // Fallback: use current origin host with ws/wss and default port/path if provided by backend
  const isHttps = typeof window !== 'undefined' && window.location.protocol === 'https:';
  const proto = isHttps ? 'wss' : 'ws';
  // If a reverse proxy exposes the chat at a path, you can change '/chat' here.
  const host = typeof window !== 'undefined' ? window.location.hostname : 'localhost';
  const port = (typeof window !== 'undefined' && window.location.port) ? `:${window.location.port}` : '';
  // On localhost, prefer dedicated chat port 1235 by default
  // Prefer IPv4 for localhost to avoid browsers resolving to ::1 (IPv6) where the server may not listen
  if (host === 'localhost' || host === '127.0.0.1' || host === '::1' || host === '[::1]') {
    return `${proto}://127.0.0.1:1235`;
  }
  // Default to same origin (no hardcoded chat port). Adjust via VITE_CHAT_WS_URL if needed.
  const defaultUrl = `${proto}://${host}${port}`;
  return defaultUrl;
}

// Provide a list of candidate WS URLs to try, in order of likelihood.
export function getChatWsCandidates() {
  const override = (typeof window !== 'undefined' && window.localStorage) ? window.localStorage.getItem('chatWsOverride') : '';
  if (override && typeof override === 'string' && override.trim()) {
    return [override.trim()];
  }
  const envUrl = import.meta?.env?.VITE_CHAT_WS_URL;
  if (envUrl && typeof envUrl === 'string' && envUrl.trim()) {
    return [envUrl.trim()];
  }
  const isHttps = typeof window !== 'undefined' && window.location.protocol === 'https:';
  const proto = isHttps ? 'wss' : 'ws';
  const host = typeof window !== 'undefined' ? window.location.hostname : 'localhost';
  const port = (typeof window !== 'undefined' && window.location.port) ? `:${window.location.port}` : '';
  const candidates = [];
  // Common local setups: include IPv4 and IPv6 loopback variants (root only)
  if (host === 'localhost' || host === '127.0.0.1' || host === '::1' || host === '[::1]') {
    // Prefer IPv6 loopback first when available
    const localHosts = ['[::1]', '127.0.0.1', 'localhost'];
    for (const h of localHosts) {
      const base = `${proto}://${h}:1235`;
  candidates.push(base);
  candidates.push(`${base}/`);
    }
  }
  // Same-origin root and common WS paths
  const sameOriginBases = [`${proto}://${host}${port}`];
  // If localhost-ish, also try 127.0.0.1 for same-origin port
  if ((host === 'localhost' || host === '::1' || host === '[::1]') && port) {
    sameOriginBases.push(`${proto}://[::1]${port}`);
    sameOriginBases.push(`${proto}://127.0.0.1${port}`);
  }
  for (const base of sameOriginBases) {
  candidates.push(base);
  candidates.push(`${base}/`);
  }
  return candidates;
}

// Return optional subprotocols for the WebSocket handshake.
export function getChatWsProtocols() {
  try {
    const ls = (typeof window !== 'undefined' && window.localStorage) ? window.localStorage.getItem('chatWsProtocols') : '';
    if (ls && ls.trim()) {
      // Accept JSON array or comma-separated
      if (ls.trim().startsWith('[')) return JSON.parse(ls);
      return ls.split(',').map(s => s.trim()).filter(Boolean);
    }
  } catch (_) {}
  const env = import.meta?.env?.VITE_CHAT_WS_PROTOCOLS;
  if (env && typeof env === 'string' && env.trim()) {
    try {
      if (env.trim().startsWith('[')) return JSON.parse(env);
    } catch (_) {}
    return env.split(',').map(s => s.trim()).filter(Boolean);
  }
  // Default to the 'chat' subprotocol so the server can gate connections accordingly
  return ['chat'];
}