convertTo12HourTimeOfDay method

TimeOfDay convertTo12HourTimeOfDay()

Convert 12-hour format string (e.g., "2:30 PM") to TimeOfDay

Implementation

TimeOfDay convertTo12HourTimeOfDay() {
  final raw = trim().toUpperCase();
  bool isNumeric(String s) =>
      s.isNotEmpty && s.codeUnits.every((c) => c >= 48 && c <= 57);

  if (!(raw.endsWith('AM') || raw.endsWith('PM'))) {
    throw const FormatException(
        'Invalid 12-hour time format. Expected format: H:MM AM/PM');
  }

  final period = raw.substring(raw.length - 2); // AM or PM
  String timePart = raw.substring(0, raw.length - 2).trim(); // remove period

  if (!timePart.contains(':')) {
    throw const FormatException(
        'Invalid 12-hour time format. Missing colon.');
  }
  final parts = timePart.split(':');
  if (parts.length != 2) {
    throw const FormatException(
        'Invalid 12-hour time format. Expected single colon.');
  }

  final hourStr = parts[0];
  final minuteStr = parts[1];
  if (!isNumeric(hourStr) ||
      !isNumeric(minuteStr) ||
      minuteStr.length != 2 ||
      hourStr.length > 2) {
    throw const FormatException(
        'Invalid 12-hour time format. Non-numeric components.');
  }
  int hour = int.parse(hourStr);
  int minute = int.parse(minuteStr);

  // Convert to 24-hour format
  if (period == 'AM') {
    if (hour == 12) hour = 0; // 12 AM is 00:00
  } else {
    // PM
    if (hour != 12) hour += 12; // Add 12 except for 12 PM
  }

  return TimeOfDay(hour: hour, minute: minute);
}