export const cachedFetch = url => {
  const key = `@MySuperStore:${url}`;
  return AsyncStorage.getItem(key)
    .then(data => {
      if (!data) {
        return Promise.reject("no data found in async storage");
      }
      console.log("found data on disk");
      return JSON.parse(data);
    })
    .catch(() => {
      console.log("didn't find data on disk, fetching");
      return fetch(url).then(response => {
        if (response.ok) {
          return response.json().then(data => {
            AsyncStorage.setItem(key, JSON.stringify(data));
            return data;
          });
        }
        return Promise.reject("unable to load data");
      });
    });
};