Pseudo code for passport sdk.

passport.js

const SESSION_STATUS = {
  NOT_LOGIN: 1,
  LOGIN: 2,
  ACCESS_TOKEN_EXPIRED: 3,
  REFRESH_TOKEN_EXPIRED: 4
};

let refresh_timer = null;

function checkAuth(callback) {
  if (noToken) {
    callback(SESSION_STATUS.NOT_LOGIN, null);
    return;
  }

  if (expired()) {
    refreshToken((error, token) => {
      if (error == SESSION_STATUS.REFRESH_TOKEN_EXPIRED) {
        jumpToLogin();
        return;
      }

      callback(null, token);
    });
    return;
  }

  callback(null, token);
  nextRefreshToken();
}

function nextRefreshToken() {
  clearTimeout(refresh_timer);
  var t = getNextRefreshTime();
  refresh_timer = setTimeout(function(){
    refreshToken(null);
  }, t);
}

function jumpToLogin() {
  console.log('show me the login!');
}

function refreshToken(callback) {
  const valid = doRefresh();
  if (valid == false) {
    callback(SESSION_STATUS.REFRESH_TOKEN_EXPIRED, null);
    return;
  }

  updateLocalSession(session);
  nextRefreshToken();
  callback(null, token);
}

function login() {
  if (fail) {
    console.log('login fail!');
    return;
  }

  updateLocalSession();
  nextRefreshToken();
  jumpBack();
}

function jumpBack() {
  console.log('Go back where you come!');
}

function updateLocalSession(session) {
  setExpiredTimestamp();
  wx.setStorageSync(key, session);
}

function setExpiredTimestamp() {
  console.log('calculate the expired timestamp');
}

function getExpiredTimestamp() {
  return '1223';
}

function expired() {
  return expired?true: false;
}