parseDateTime function

DateTime? parseDateTime(dynamic o, [ DateTime? def, String? locale ])

Parses o as DateTime, trying many formats. If can't parse returns def.

Implementation

DateTime? parseDateTime(dynamic o, [DateTime? def, String? locale]) {
  if (o == null) return def;
  if (o is DateTime) return o;

  var s = o.toString().trim();
  if (s.isEmpty) return def;

  var d = DateTime.tryParse(s);
  if (d != null) return d;

  var m = _regexpDateTimeFormat.firstMatch(s);

  if (m == null) {
    return def;
  }

  var yd1 = int.parse(m.group(1)!);
  var md = int.parse(m.group(2)!);
  var yd2 = int.parse(m.group(3)!);
  var hourStr = m.group(4);
  var minStr = m.group(5);
  var secStr = m.group(6);
  var zoneStr = m.group(7);

  int year;
  int day;
  int month;
  if (yd1 > 31 && yd2 <= 31) {
    year = yd1;
    day = yd2;
  } else if (yd2 > 31 && yd1 <= 31) {
    year = yd2;
    day = yd1;
  } else {
    return null;
  }

  if (year < 100) {
    if (year >= 70) {
      year = 1900 + year;
    } else {
      year = 2000 + year;
    }
  }

  if (md > 12) {
    month = day;
    day = md;
  } else {
    month = md;
  }

  if (hourStr != null) {
    var hour = int.parse(hourStr);
    var min = int.parse(minStr!);
    var sec = secStr != null ? int.parse(secStr) : 0;

    if (zoneStr == null) {
      return DateTime(year, month, day, hour, min, sec);
    }

    try {
      var dateStr = '$year-'
          '${month.toString().padLeft(2, '0')}-'
          '${day.toString().padLeft(2, '0')} '
          '$hour:$min:$sec $zoneStr';

      return DateTime.parse(dateStr);
    } on FormatException {
      return null;
    }
  } else {
    return DateTime(year, month, day);
  }
}