import 'package:flutter/material.dart';
import '../models/work_day.dart';

/// Kurzcode-Liste & Label
const List<String> kAbsenceCodes = ['G', 'K', 'U', 'SU', 'T'];

String codeLabel(String code) {
  switch (code) {
    case 'G':  return 'Gleitzeit';
    case 'K':  return 'Krankenstand';
    case 'U':  return 'Urlaub';
    case 'SU': return 'Sonderurlaub';
    case 'T':  return 'Training';
    default:   return code;
  }
}

/// Zeit-Helfer
TimeOfDay? parseDbTime(String? hhmmss) {
  if (hhmmss == null || hhmmss.isEmpty) return null;
  final parts = hhmmss.split(':');
  if (parts.length < 2) return null;
  final h = int.tryParse(parts[0]) ?? 0;
  final m = int.tryParse(parts[1]) ?? 0;
  return TimeOfDay(hour: h, minute: m);
}

String fmtTimeOfDay(TimeOfDay? t) {
  if (t == null) return '';
  final hh = t.hour.toString().padLeft(2, '0');
  final mm = t.minute.toString().padLeft(2, '0');
  return '$hh:$mm';
}

TimeOfDay? parseTextHHMM(String s) {
  if (s.length != 5 || s[2] != ':') return null;
  final h = int.tryParse(s.substring(0, 2));
  final m = int.tryParse(s.substring(3, 5));
  if (h == null || m == null) return null;
  if (h < 0 || h > 23 || m < 0 || m > 59) return null;
  return TimeOfDay(hour: h, minute: m);
}

String minutesToHHMM(int minutes) {
  final sign = minutes < 0 ? '-' : '';
  final m = minutes.abs();
  final hh = (m ~/ 60).toString().padLeft(2, '0');
  final mm = (m % 60).toString().padLeft(2, '0');
  return '$sign$hh:$mm';
}

String minutesToSignedHHMM(int minutes) => minutesToHHMM(minutes);

/// Datums-Formatierungen
String ymd(DateTime d) =>
    '${d.year.toString().padLeft(4, '0')}-${d.month.toString().padLeft(2, '0')}-${d.day.toString().padLeft(2, '0')}';

const _weekdayShort = ['Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa', 'So'];

String _shortWeekday(DateTime d) => _weekdayShort[(d.weekday - 1) % 7];
String _shortDate(DateTime d) =>
    '${d.day.toString().padLeft(2, '0')}.${d.month.toString().padLeft(2, '0')}.';

/// Links in der Tabelle (Tag vor Datum)
String rightDayLabel(DateTime d) => '${_shortWeekday(d)} ${_shortDate(d)}';

/// Rechts in der Tabelle (Datum vor Tag)
String leftDayLabel(DateTime d) => '${_shortDate(d)} ${_shortWeekday(d)}';

const _monthNames = [
  'Jänner', 'Februar', 'März', 'April', 'Mai', 'Juni',
  'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'
];

String monthTitle(DateTime m) => '${_monthNames[m.month - 1]} ${m.year}';

/// Füllt den kompletten Monat mit leeren Tagen, ersetzt vorhandene Einträge
List<WorkDay> fillMonth(DateTime monthStart, List<WorkDay> fromApi) {
  final m0 = DateTime(monthStart.year, monthStart.month, 1);
  final m1 = DateTime(monthStart.year, monthStart.month + 1, 1);
  final byDay = <String, WorkDay>{for (final d in fromApi) ymd(d.date): d};

  final days = <WorkDay>[];
  for (DateTime d = m0; d.isBefore(m1); d = d.add(const Duration(days: 1))) {
    final k = ymd(d);
    if (byDay.containsKey(k)) {
      final v = byDay[k]!;
      days.add(WorkDay(
        date: d,
        intervals: v.intervals,
        targetMinutes: v.targetMinutes,
        code: v.code,
      ));
    } else {
      days.add(WorkDay(date: d, intervals: const [], targetMinutes: 0, code: null));
    }
  }
  return days;
}