getDuration function

String? getDuration(String duration)

Implementation

String? getDuration(String duration) {
  if (duration.isEmpty) return null;
  duration = duration.replaceFirst("PT", "");

  var validDuration = ["H", "M", "S"];
  if (!duration.contains(new RegExp(r'[HMS]'))) {
    return null;
  }
  var hour = 0, min = 0, sec = 0;
  for (int i = 0; i < validDuration.length; i++) {
    var index = duration.indexOf(validDuration[i]);
    if (index != -1) {
      var valInString = duration.substring(0, index);
      var val = int.parse(valInString);
      if (i == 0)
        hour = val;
      else if (i == 1)
        min = val;
      else if (i == 2) sec = val;
      duration = duration.substring(valInString.length + 1);
    }
  }
  List buff = [];
  if (hour != 0) {
    buff.add(hour);
  }
  if (min == 0) {
    if (hour != 0) buff.add(min.toString().padLeft(2, '0'));
  } else {
    buff.add(min.toString().padLeft(2, '0'));
  }
  buff.add(sec.toString().padLeft(2, '0'));

  return buff.join(":");
}