cache.js

export const defaultCache = store => {
  return {
    invalidate: hash =>
      new Promise(resolve => {
        delete store[hash];
        resolve(hash);
      }),
    invalidateAll: () =>
      new Promise(resolve => {
        store = {};
        resolve();
      }),
    read: hash =>
      new Promise(resolve => {
        resolve(store[hash] || null);
      }),
    update: callback =>
      new Promise(resolve => {
        if (typeof callback === 'function') {
          Object.keys(store).forEach(key => {
            callback(store, key, store[key]);
          });
        }
        resolve();
      }),
    write: (hash, data) =>
      new Promise(resolve => {
        store[hash] = data;
        resolve(hash);
      }),
  };
};