import once from 'lodash.once';
import { DataRequestTypeEnum, SendOrCacheDataProps, RequestData } from '../types/signal.types';
import { EVENTS_CACHE_KEY } from '../constants/constants';

export const supportsLocalStorage = once(() => {
  const value = '_OMBORI_GRID_SIGNALS_CACHE_TEST';

  try {
    localStorage.setItem(value, value);
    localStorage.removeItem(value);
    return true;
  } catch (e) {
    return false;
  }
});

export const cache: any[] = supportsLocalStorage()
  ? JSON.parse(localStorage.getItem(EVENTS_CACHE_KEY) || '[]')
  : [];

export const cacheData = (type: DataRequestTypeEnum, data: RequestData) => {
  // If the device is offline for a long time we don't want the cache to grow infinitely
  if (cache.length >= 10000) {
    cache.shift();
  }

  cache.push({ type, data });

  supportsLocalStorage() && localStorage.setItem(EVENTS_CACHE_KEY, JSON.stringify(cache));
};

const delay = (ms: number) =>
  new Promise(resolve => {
    setTimeout(resolve, ms);
  });

const flushCache = async (sendOrCacheData: SendOrCacheDataProps) => {
  while (cache.length) {
    const event = cache.shift();
    if (event) {
      sendOrCacheData(event.type, event.data);
      // Don't flush the cache too quickly as it can lead to dropped events
      await delay(100);
    }
  }

  supportsLocalStorage() && localStorage.removeItem(EVENTS_CACHE_KEY);

  flushCacheOnce = once(flushCache);
};

export let flushCacheOnce = once(flushCache);