import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:provider/provider.dart';
import '../models/schedule_item.dart';
import '../services/schedule_service.dart';

class CalendarWidget extends StatefulWidget {
  const CalendarWidget({super.key});

  @override
  State<CalendarWidget> createState() => _CalendarWidgetState();
}

class _CalendarWidgetState extends State<CalendarWidget> {
  List<ScheduleItem> _schedules = [];

  @override
  void initState() {
    super.initState();
    _loadSchedules();
  }

  Future<void> _loadSchedules() async {
    try {
      final schedules =
          await Provider.of<ScheduleService>(context, listen: false)
              .fetchMonthlySchedules();
      if (mounted) {
        setState(() {
          _schedules = schedules;
        });
      }
    } catch (e) {
      debugPrint('Error loading schedules: $e');
    }
  }

  bool _hasScheduleOn(DateTime date) {
    final checkDate = DateTime(date.year, date.month, date.day);
    return _schedules.any((s) {
      final start =
          DateTime(s.startDate.year, s.startDate.month, s.startDate.day);
      final end = DateTime(s.endDate.year, s.endDate.month, s.endDate.day);
      return (checkDate.isAtSameMomentAs(start) || checkDate.isAfter(start)) &&
          (checkDate.isAtSameMomentAs(end) || checkDate.isBefore(end));
    });
  }

  @override
  Widget build(BuildContext context) {
    final now = DateTime.now();
    final firstDayOfMonth = DateTime(now.year, now.month, 1);
    final lastDayOfMonth = DateTime(now.year, now.month + 1, 0);
    final daysInMonth = lastDayOfMonth.day;
    final startingWeekday = firstDayOfMonth.weekday; // Mon=1, Sun=7

    int offset = startingWeekday % 7;

    return Container(
      padding: const EdgeInsets.all(8),
      decoration: BoxDecoration(
        color: Theme.of(context).cardTheme.color,
        borderRadius: BorderRadius.circular(16),
      ),
      child: Column(
        children: [
          // Header
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  DateFormat('yyyy년 M월').format(now),
                  style: Theme.of(context).textTheme.titleLarge?.copyWith(
                        fontWeight: FontWeight.bold,
                        color: Colors.white,
                        fontSize: 20,
                      ),
                ),
                const Icon(Icons.calendar_today,
                    color: Colors.white54, size: 20),
              ],
            ),
          ),
          const SizedBox(height: 8),
          // Days Header
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: ['일', '월', '화', '수', '목', '금', '토'].asMap().entries.map((entry) {
              final isSunday = entry.key == 0;
              return Expanded(
                child: Center(
                  child: Text(
                    entry.value,
                    style: TextStyle(
                      color: isSunday ? Colors.redAccent : Colors.white54,
                      fontWeight: FontWeight.bold,
                      fontSize: 14,
                    ),
                  ),
                ),
              );
            }).toList(),
          ),
          const SizedBox(height: 4),
          // Days Grid
          Expanded(
            child: Column(
              children: List.generate(6, (row) {
                return Expanded(
                  child: Row(
                    children: List.generate(7, (col) {
                      final index = row * 7 + col;
                      final dayNumber = index - offset + 1;
                      final isSunday = col == 0;

                      if (dayNumber < 1 || dayNumber > daysInMonth) {
                        return const Expanded(child: SizedBox.shrink());
                      }

                      final dayDate =
                          DateTime(now.year, now.month, dayNumber);
                      final isToday = dayNumber == now.day;
                      final hasSchedule = _hasScheduleOn(dayDate);

                      return Expanded(
                        child: Container(
                          margin: const EdgeInsets.all(1),
                          decoration: isToday
                              ? BoxDecoration(
                                  border: Border.all(
                                    color: Theme.of(context).colorScheme.primary,
                                    width: 2,
                                  ),
                                  shape: BoxShape.circle,
                                )
                              : null,
                          child: Stack(
                            alignment: Alignment.center,
                            children: [
                              Center(
                                child: FittedBox(
                                  fit: BoxFit.scaleDown,
                                  child: Text(
                                    '$dayNumber',
                                    style: TextStyle(
                                      color: isToday
                                          ? Theme.of(context).colorScheme.primary
                                          : (isSunday ? Colors.redAccent : Colors.white),
                                      fontWeight: FontWeight.bold,
                                      fontSize: 18,
                                    ),
                                  ),
                                ),
                              ),
                              if (hasSchedule) // Show indicator even if it's today
                                Positioned(
                                  bottom: 2,
                                  child: Container(
                                    width: 14,
                                    height: 4,
                                    decoration: BoxDecoration(
                                      color: Colors.yellowAccent,
                                      borderRadius: BorderRadius.circular(2),
                                    ),
                                  ),
                                ),
                            ],
                          ),
                        ),
                      );
                    }),
                  ),
                );
              }),
            ),
          ),
        ],
      ),
    );
  }
}