index.js

const Observable = require("zen-observable");

let data = {};
let handlers = [];

const escapeRegexp = require('escape-regex')

const keyRegex = (str) => {
  str = str.split('*').map( s => escapeRegexp(s)).join('*')
  return new RegExp('^' + str.replace('*','.*'))
}

const observable = new Observable(observer => {
  handlers.push(data => observer.next(data));
  let index = handlers.length;
  return () => {
    handlers = [...handlers.slice(0, index), ...handlers.slice(index)];
  };
});

function get(key, options) {
  const value = data[key] || { views: [] };
  return Promise.resolve({
    views: value.views.filter(view => {
      if (options && options.before && view.time > options.before) return false;
      if (options && options.after && view.time < options.after) return false;
      return true;
    })
  });
}

function keys() {
  return Promise.resolve(Object.keys(data));
}

function put(key, value) {
  data[key] = value;
  handlers.forEach(handler => {
    handler({ key, value });
  });

  return Promise.resolve();
}

async function getAll(options) {
  const value = {};
  const _keys = (await keys()).filter(
    key =>
      options.ignoreWildcard
        ? key.startsWith(options.pathname)
        : key.match(keyRegex(options.pathname))
  );

  for (let key of _keys) {
    value[key] = await get(key, {
      before: options.before,
      after: options.after
    });
  }

  return Promise.resolve(value);
}

function has(key) {
  return Promise.resolve({}.hasOwnProperty.call(data, key));
}

function clear() {
  data = {};
}

function subscribe(listener) {
  return observable.subscribe(listener);
}

module.exports = { get, put, getAll, has, keys, clear, subscribe };