var timerSpan = document.getElementById("timerSpan");

var startTime = null;
var doneTimeMilliseconds = null;

update();

document.addEventListener("keydown", function(e) {
  switch (e.keyCode) {
    case 32: // spacebear
      if (startTime == null) {
        startTime = new Date();
        doneTimeMilliseconds = null;
      } else {
        doneTimeMilliseconds = new Date() - startTime;
        startTime = null;
      }
      break;
    case 84: // t is for test
      startTime = null;
      doneTimeMilliseconds = 10000000;
      break;
    case 82: // r is for reset
      startTime = null;
      doneTimeMilliseconds = null;
      break;
  }
});

function update() {
  var milliseconds = 0;
  if (startTime != null) milliseconds = new Date() - startTime;
  if (doneTimeMilliseconds != null) milliseconds = doneTimeMilliseconds;
  timerSpan.textContent = formatTime(milliseconds);
  requestAnimationFrame(update);
}

function formatTime(milliseconds) {
  var centiseconds = Math.floor(milliseconds / 10);
  var seconds = Math.floor(centiseconds / 100);
  var minutes = Math.floor(seconds / 60);
  var hours = Math.floor(minutes / 60);
  var result = "";
  if (hours !== 0) {
    result += hours.toString() + ":";
    result += zfill(minutes % 60, 2) + ":";
    result += zfill(seconds % 60, 2) + ".";
  } else {
    if (minutes !== 0) {
      result += minutes.toString() + ":";
      result += zfill(seconds % 60, 2) + ".";
    } else {
      result += seconds.toString() + ".";
    }
  }
  result += zfill(centiseconds % 100, 2);
  return result;
}

function zfill(number, digits) {
  var result = number.toString();
  while (result.length < digits) {
    result = "0" + result;
  }
  return result;
}