public-fuse/src/util/offline.ts

export const isOfflineMode = (): boolean => {
  try {
    const envFlag = import.meta.env.VITE_OFFLINE;
    return envFlag === 'true' || envFlag;
  } catch (e) {
    return false;
  }
};

export const getOfflineDataPath = (): string => {
  try {
    const p = import.meta.env.VITE_OFFLINE_DATA_PATH;
    return p || './';
  } catch (e) {
    return './';
  }
};

export const fetchOfflineJson = async <T = any>(candidatePaths: string[]): Promise<T> => {
  const errors: any[] = [];
  for (const p of candidatePaths) {
    try {
      const res = await fetch(p, { cache: 'no-store' });
      if (!res.ok) {
        errors.push(`${p}: ${res.status}`);
        continue;
      }
      return (await res.json()) as T;
    } catch (e) {
      errors.push(`${p}: ${(e as Error)?.message || 'fetch failed'}`);
    }
  }
  throw new Error(`offline json not found. tried: ${errors.join('; ')}`);
};