export const downloadRootDir: string;
export const packageVersion: string;
export const currentVersion: string;
export const isFirstTime: boolean;
export const isRolledBack: boolean;

export interface ExpiredResult {
  expired: true;
  downloadUrl: string;
}

export interface UpTodateResult {
  upToDate: true;
}

export interface UpdateAvailableResult {
  update: true;
  name: string; // version name
  hash: string;
  description: string;
  metaInfo: string;
  pdiffUrl: string;
  diffUrl: string;
}

export type CheckResult = Partial<ExpiredResult & UpTodateResult & UpdateAvailableResult>;

export function checkUpdate(appkey: string): Promise<CheckResult>;

export function downloadUpdate(options: UpdateAvailableResult): Promise<undefined | string>;

export function switchVersion(hash: string): void;

export function switchVersionLater(hash: string): void;

export function markSuccess(): void;