const updateClock = (start, e) => {
  let timeSince = new Date().getTime() - start;

  let days = Math.floor(timeSince / (1000 * 60 * 60 * 24));
  let hours = Math.floor(
    (timeSince % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60),
  );
  let minutes = Math.floor((timeSince % (1000 * 60 * 60)) / (1000 * 60));
  let seconds = Math.floor((timeSince % (1000 * 60)) / 1000);

  const elems = e.getElementsByTagName("p");

  for (const e of elems) {
    switch (e.id) {
      case "d":
        e.innerHTML = days + "d";
        break;
      case "h":
        e.innerHTML = hours + "h";
        break;
      case "m":
        e.innerHTML = minutes + "m";
        break;
      case "s":
        e.innerHTML = seconds + "s";
        break;
      default:
        break;
    }
  }
};

const applyClock = (e) => {
  const startattr = e.getAttributeNode("x-start-time");
  if (startattr === null) return;

  const start = Number.parseInt(startattr.value);

  setInterval(() => updateClock(start, e), 1000);
};

const clocks = document.getElementsByClassName("clock");
for (const e of clocks) {
  applyClock(e);
}