import 'package:flutter/material.dart';
import '../../../core/theme/app_theme.dart';
import '../../../core/widgets/glass_container.dart';

/// Compact Interactive Monthly Calendar Grid with event markers and event count dots.
class MonthCalendarWidget extends StatelessWidget {
  final DateTime currentMonth;
  final DateTime? selectedDate;
  final List<dynamic> events;
  final Function(DateTime) onDateSelected;
  final Function(DateTime) onMonthChanged;

  const MonthCalendarWidget({
    super.key,
    required this.currentMonth,
    required this.selectedDate,
    required this.events,
    required this.onDateSelected,
    required this.onMonthChanged,
  });

  static const List<String> weekDays = ['Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa', 'So'];
  static const List<String> monthNames = [
    'Januar', 'Februar', 'März', 'April', 'Mai', 'Juni',
    'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'
  ];

  DateTime _parseEventDate(dynamic raw) {
    if (raw == null) return DateTime(1970);
    final str = raw.toString();
    try {
      if (str.contains('.')) {
        final parts = str.split('.');
        if (parts.length >= 3) {
          return DateTime(int.parse(parts[2]), int.parse(parts[1]), int.parse(parts[0]));
        }
      }
      return DateTime.parse(str);
    } catch (_) {
      return DateTime(1970);
    }
  }

  List<dynamic> _getEventsForDate(DateTime date) {
    return events.where((e) {
      final dt = _parseEventDate(e['eventDate'] ?? e['EventDate']);
      return dt.year == date.year && dt.month == date.month && dt.day == date.day;
    }).toList();
  }

  @override
  Widget build(BuildContext context) {
    final firstDayOfMonth = DateTime(currentMonth.year, currentMonth.month, 1);
    final daysInMonth = DateTime(currentMonth.year, currentMonth.month + 1, 0).day;
    
    // ISO weekday: Monday = 1, Sunday = 7
    final firstWeekday = firstDayOfMonth.weekday;
    final leadingEmptyDays = firstWeekday - 1;
    final totalCells = ((leadingEmptyDays + daysInMonth) / 7).ceil() * 7;

    return Center(
      child: Container(
        child: GlassContainer(
          padding: const EdgeInsets.all(12),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              // Month Header Navigation
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  IconButton(
                    icon: Icon(Icons.chevron_left, color: AppTheme.accentCyan, size: 20),
                    padding: EdgeInsets.zero,
                    constraints: const BoxConstraints(),
                    onPressed: () => onMonthChanged(DateTime(currentMonth.year, currentMonth.month - 1, 1)),
                  ),
                  Text(
                    '${monthNames[currentMonth.month - 1]} ${currentMonth.year}',
                    style: TextStyle(fontWeight: FontWeight.bold, fontSize: 14, color: AppTheme.textPrimary),
                  ),
                  IconButton(
                    icon: Icon(Icons.chevron_right, color: AppTheme.accentCyan, size: 20),
                    padding: EdgeInsets.zero,
                    constraints: const BoxConstraints(),
                    onPressed: () => onMonthChanged(DateTime(currentMonth.year, currentMonth.month + 1, 1)),
                  ),
                ],
              ),
              const SizedBox(height: 6),
              // Weekday Labels
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceAround,
                children: weekDays.map((w) => Expanded(
                  child: Center(
                    child: Text(
                      w,
                      style: TextStyle(color: AppTheme.textMuted, fontSize: 11, fontWeight: FontWeight.bold),
                    ),
                  ),
                )).toList(),
              ),
              const SizedBox(height: 4),
              // Days Grid
              GridView.builder(
                shrinkWrap: true,
                physics: const NeverScrollableScrollPhysics(),
                itemCount: totalCells,
                gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                  crossAxisCount: 7,
                  childAspectRatio: 2,
                ),
                itemBuilder: (context, index) {
                  final dayNumber = index - leadingEmptyDays + 1;
                  if (dayNumber < 1 || dayNumber > daysInMonth) {
                    return const SizedBox();
                  }

                  final cellDate = DateTime(currentMonth.year, currentMonth.month, dayNumber);
                  final isSelected = selectedDate != null &&
                      selectedDate!.year == cellDate.year &&
                      selectedDate!.month == cellDate.month &&
                      selectedDate!.day == cellDate.day;

                  final isToday = DateTime.now().year == cellDate.year &&
                      DateTime.now().month == cellDate.month &&
                      DateTime.now().day == cellDate.day;

                  final dayEvents = _getEventsForDate(cellDate);
                  final eventCount = dayEvents.length;

                  return InkWell(
                    onTap: () => onDateSelected(cellDate),
                    borderRadius: BorderRadius.circular(6),
                    child: Container(
                      margin: const EdgeInsets.all(1.5),
                      decoration: BoxDecoration(
                        color: isSelected
                            ? AppTheme.primaryEmerald.withValues(alpha: 0.3)
                            : (isToday ? AppTheme.glassSurface : Colors.transparent),
                        borderRadius: BorderRadius.circular(6),
                        border: Border.all(
                          color: isSelected
                              ? AppTheme.primaryEmerald
                              : (eventCount > 0 ? AppTheme.accentCyan.withValues(alpha: 0.6) : Colors.transparent),
                          width: isSelected ? 1.5 : 1.0,
                        ),
                      ),
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Text(
                            '$dayNumber',
                            style: TextStyle(
                              fontSize: 11.5,
                              fontWeight: isSelected || isToday || eventCount > 0 ? FontWeight.bold : FontWeight.normal,
                              color: isSelected
                                  ? AppTheme.primaryEmerald
                                  : (eventCount > 0 ? AppTheme.textPrimary : AppTheme.textSecondary),
                            ),
                          ),
                          if (eventCount > 0) ...[
                            const SizedBox(height: 1),
                            Row(
                              mainAxisAlignment: MainAxisAlignment.center,
                              children: List.generate(
                                eventCount > 4 ? 4 : eventCount,
                                (i) => Container(
                                  margin: const EdgeInsets.symmetric(horizontal: 1),
                                  width: 4,
                                  height: 4,
                                  decoration: BoxDecoration(
                                    color: AppTheme.accentCyan,
                                    shape: BoxShape.circle,
                                  ),
                                ),
                              ),
                            ),
                          ],
                        ],
                      ),
                    ),
                  );
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}