5chan/src/hooks/use-time-filter.js

import assert from 'assert';
import { useParams } from 'react-router-dom';

// the timestamp the last time the user visited
const lastVisitTimestamp = localStorage.getItem('plebchanLastVisitTimestamp');

// update the last visited timestamp every n seconds
setInterval(() => {
  localStorage.setItem('plebchanLastVisitTimestamp', Date.now());
}, 60 * 1000);

const timeFilterNamesToSeconds = {
  '1h': 60 * 60,
  '12h': 60 * 60 * 12,
  '24h': 60 * 60 * 24,
  '48h': 60 * 60 * 24 * 2,
  week: 60 * 60 * 24 * 7,
  month: 60 * 60 * 24 * 30,
  year: 60 * 60 * 24 * 365,
  all: undefined,
};

// calculate the last visit timeFilterNamesToSeconds
const secondsSinceLastVisit = lastVisitTimestamp ? (Date.now() - lastVisitTimestamp) / 1000 : Infinity;
const day = 24 * 60 * 60;
let lastVisitTimeFilterName;
if (secondsSinceLastVisit > 30 * day) {
  lastVisitTimeFilterName = 'month';
  timeFilterNamesToSeconds[lastVisitTimeFilterName] = timeFilterNamesToSeconds['month'];
} else if (secondsSinceLastVisit > 7 * day) {
  const weeks = Math.ceil(secondsSinceLastVisit / day / 7);
  lastVisitTimeFilterName = `${weeks}w`;
  timeFilterNamesToSeconds[lastVisitTimeFilterName] = 60 * 60 * 24 * 7 * weeks;
} else if (secondsSinceLastVisit > day) {
  const days = Math.ceil(secondsSinceLastVisit / day);
  lastVisitTimeFilterName = `${days}d`;
  timeFilterNamesToSeconds[lastVisitTimeFilterName] = 60 * 60 * 24 * days;
} else {
  lastVisitTimeFilterName = '24h';
  timeFilterNamesToSeconds[lastVisitTimeFilterName] = timeFilterNamesToSeconds['24h'];
}

export const timeFilterNames = [lastVisitTimeFilterName, '1h', '12h', '24h', '48h', 'week', 'month', 'year', 'all'];

const useTimeFilter = () => {
  const params = useParams();
  let timeFilterName = params.timeFilterName;

  // the default time filter is the last visit time filter
  if (!timeFilterName) {
    timeFilterName = lastVisitTimeFilterName;
  }

  assert(!timeFilterName || typeof timeFilterName === 'string', `useTimeFilter timeFilterName argument '${timeFilterName}' not a string`);
  const timeFilterSeconds = timeFilterNamesToSeconds[timeFilterName];
  assert(!timeFilterName || timeFilterName === 'all' || timeFilterSeconds !== undefined, `useTimeFilter no filter for timeFilterName '${timeFilterName}'`);
  return { timeFilterSeconds, timeFilterNames };
};

export default useTimeFilter;