/// Parses the text values produced by [LinuxMonitor] into numbers for
/// display. Anything that does not match stays null, and the UI then shows
/// the original text instead of a guess.
class MetricValues {
  final double? cpu, ramPercent, diskPercent, uptimeSeconds;
  final int? ramUsedBytes, ramTotalBytes, diskUsedBytes, diskTotalBytes;
  final List<double>? load;
  const MetricValues({
    this.cpu,
    this.ramPercent,
    this.ramUsedBytes,
    this.ramTotalBytes,
    this.diskPercent,
    this.diskUsedBytes,
    this.diskTotalBytes,
    this.uptimeSeconds,
    this.load,
  });

  static final _percent = RegExp(r'^\s*([0-9]+(?:\.[0-9]+)?)\s*%');
  static final _ram = RegExp(r'\((\d+) / (\d+) MiB\)');
  static final _disk = RegExp(r'\((\d+) / (\d+) KiB\)');

  factory MetricValues.parse(Map<String, String> m) {
    double? percent(String? v) =>
        v == null ? null : double.tryParse(_percent.firstMatch(v)?[1] ?? '');
    final ram = _ram.firstMatch(m['ram'] ?? '');
    final disk = _disk.firstMatch(m['disk'] ?? '');
    final load = (m['load'] ?? '')
        .trim()
        .split(RegExp(r'\s+'))
        .map(double.tryParse)
        .toList();
    final uptime = double.tryParse((m['uptime'] ?? '').trim());
    return MetricValues(
      cpu: percent(m['cpu']),
      ramPercent: percent(m['ram']),
      ramUsedBytes: ram == null ? null : int.parse(ram[1]!) * 1024 * 1024,
      ramTotalBytes: ram == null ? null : int.parse(ram[2]!) * 1024 * 1024,
      diskPercent: percent(m['disk']),
      diskUsedBytes: disk == null ? null : int.parse(disk[1]!) * 1024,
      diskTotalBytes: disk == null ? null : int.parse(disk[2]!) * 1024,
      uptimeSeconds: uptime != null && uptime >= 0 ? uptime : null,
      load: load.length == 3 && load.every((v) => v != null && v >= 0)
          ? load.cast<double>()
          : null,
    );
  }
}

/// Whole days, hours and minutes of an uptime in seconds.
({int days, int hours, int minutes}) splitUptime(double seconds) {
  final total = seconds.floor() ~/ 60;
  return (days: total ~/ 1440, hours: total % 1440 ~/ 60, minutes: total % 60);
}

/// Binary (IEC) units, as reported by the kernel: 1 KiB = 1024 bytes.
/// [decimal] formats the number for the locale, e.g. "1,9" in Czech.
String formatBytes(int bytes, String Function(double, int digits) decimal) {
  const units = ['B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB'];
  var value = bytes.toDouble();
  var unit = 0;
  while (value >= 1024 && unit < units.length - 1) {
    value /= 1024;
    unit++;
  }
  final digits = unit == 0 || value >= 100 ? 0 : 1;
  return '${decimal(value, digits)} ${units[unit]}';
}