import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import '../../../data/models/maintenance_dto.dart';

class MaintenanceCalendar extends StatefulWidget {
  final List<MaintenanceDto> maintenances;
  final Function(DateTime)? onDateSelected;
  
  const MaintenanceCalendar({
    super.key,
    required this.maintenances,
    this.onDateSelected,
  });
  
  @override
  State<MaintenanceCalendar> createState() => _MaintenanceCalendarState();
}

class _MaintenanceCalendarState extends State<MaintenanceCalendar> {
  late DateTime _selectedMonth;
  DateTime? _selectedDate;
  
  @override
  void initState() {
    super.initState();
    _selectedMonth = DateTime.now();
  }
  
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        _buildMonthSelector(),
        Expanded(
          child: _buildCalendarGrid(),
        ),
      ],
    );
  }
  
  Widget _buildMonthSelector() {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 16),
      decoration: BoxDecoration(
        color: Colors.white,
        boxShadow: [
          BoxShadow(
            color: Colors.grey.withValues(alpha: 0.1),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          IconButton(
            icon: const Icon(Icons.chevron_left),
            onPressed: () {
              setState(() {
                _selectedMonth = DateTime(
                  _selectedMonth.year,
                  _selectedMonth.month - 1,
                );
              });
            },
          ),
          Text(
            DateFormat('yyyy년 MM월').format(_selectedMonth),
            style: Theme.of(context).textTheme.titleLarge?.copyWith(
              fontWeight: FontWeight.bold,
            ),
          ),
          IconButton(
            icon: const Icon(Icons.chevron_right),
            onPressed: () {
              setState(() {
                _selectedMonth = DateTime(
                  _selectedMonth.year,
                  _selectedMonth.month + 1,
                );
              });
            },
          ),
        ],
      ),
    );
  }
  
  Widget _buildCalendarGrid() {
    final firstDay = DateTime(_selectedMonth.year, _selectedMonth.month, 1);
    final lastDay = DateTime(_selectedMonth.year, _selectedMonth.month + 1, 0);
    final startWeekday = firstDay.weekday % 7; // 일요일 = 0
    
    // 달력 셀 생성
    final days = <Widget>[];
    
    // 요일 헤더
    const weekdays = ['일', '월', '화', '수', '목', '금', '토'];
    for (int i = 0; i < 7; i++) {
      days.add(
        Container(
          alignment: Alignment.center,
          padding: const EdgeInsets.symmetric(vertical: 12),
          child: Text(
            weekdays[i],
            style: TextStyle(
              fontWeight: FontWeight.bold,
              color: i == 0 ? Colors.red : (i == 6 ? Colors.blue : Colors.black),
            ),
          ),
        ),
      );
    }
    
    // 이전 달 빈 칸
    for (int i = 0; i < startWeekday; i++) {
      days.add(Container());
    }
    
    // 현재 달 날짜
    for (int day = 1; day <= lastDay.day; day++) {
      final date = DateTime(_selectedMonth.year, _selectedMonth.month, day);
      final dayMaintenances = _getMaintenancesForDate(date);
      final isToday = _isToday(date);
      final isSelected = _selectedDate != null && _isSameDay(date, _selectedDate!);
      final isWeekend = date.weekday == DateTime.sunday || date.weekday == DateTime.saturday;
      
      days.add(
        InkWell(
          onTap: () {
            setState(() {
              _selectedDate = date;
            });
            if (widget.onDateSelected != null && dayMaintenances.isNotEmpty) {
              widget.onDateSelected!(date);
            }
          },
          child: Container(
            margin: const EdgeInsets.all(2),
            decoration: BoxDecoration(
              color: isSelected
                  ? Theme.of(context).primaryColor.withValues(alpha: 0.2)
                  : isToday
                      ? Colors.blue.withValues(alpha: 0.1)
                      : Colors.transparent,
              border: Border.all(
                color: isSelected
                    ? Theme.of(context).primaryColor
                    : isToday
                        ? Colors.blue
                        : Colors.transparent,
                width: isSelected || isToday ? 2 : 1,
              ),
              borderRadius: BorderRadius.circular(8),
            ),
            child: Stack(
              children: [
                // 날짜 숫자
                Positioned(
                  top: 8,
                  left: 8,
                  child: Text(
                    day.toString(),
                    style: TextStyle(
                      fontWeight: isToday ? FontWeight.bold : FontWeight.normal,
                      color: isWeekend
                          ? (date.weekday == DateTime.sunday ? Colors.red : Colors.blue)
                          : Colors.black,
                    ),
                  ),
                ),
                
                // 유지보수 표시
                if (dayMaintenances.isNotEmpty)
                  Positioned(
                    bottom: 4,
                    left: 4,
                    right: 4,
                    child: Column(
                      children: dayMaintenances.take(3).map((m) {
                        return Container(
                          margin: const EdgeInsets.symmetric(vertical: 1),
                          padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 2),
                          decoration: BoxDecoration(
                            color: _getMaintenanceColor(m),
                            borderRadius: BorderRadius.circular(4),
                          ),
                          child: Text(
                            '#${m.equipmentHistoryId}',
                            style: const TextStyle(
                              fontSize: 10,
                              color: Colors.white,
                            ),
                            overflow: TextOverflow.ellipsis,
                          ),
                        );
                      }).toList(),
                    ),
                  ),
                
                // 더 많은 일정이 있을 때
                if (dayMaintenances.length > 3)
                  Positioned(
                    bottom: 2,
                    right: 2,
                    child: Container(
                      padding: const EdgeInsets.all(2),
                      decoration: BoxDecoration(
                        color: Colors.grey[600],
                        shape: BoxShape.circle,
                      ),
                      child: Text(
                        '+${dayMaintenances.length - 3}',
                        style: const TextStyle(
                          fontSize: 8,
                          color: Colors.white,
                        ),
                      ),
                    ),
                  ),
              ],
            ),
          ),
        ),
      );
    }
    
    return Container(
      padding: const EdgeInsets.all(16),
      child: GridView.count(
        crossAxisCount: 7,
        childAspectRatio: 1.2,
        children: days,
      ),
    );
  }
  
  List<MaintenanceDto> _getMaintenancesForDate(DateTime date) {
    return widget.maintenances.where((m) {
      // nextMaintenanceDate 필드가 백엔드에 없으므로 startedAt~endedAt 기간으로 확인
      final targetDate = DateTime(date.year, date.month, date.day);
      final startDate = DateTime(m.startedAt.year, m.startedAt.month, m.startedAt.day);
      final endDate = DateTime(m.endedAt.year, m.endedAt.month, m.endedAt.day);
      
      return (targetDate.isAfter(startDate) || targetDate.isAtSameMomentAs(startDate)) &&
             (targetDate.isBefore(endDate) || targetDate.isAtSameMomentAs(endDate));
    }).toList();
  }
  
  bool _isSameDay(DateTime date1, DateTime date2) {
    return date1.year == date2.year &&
           date1.month == date2.month &&
           date1.day == date2.day;
  }
  
  bool _isToday(DateTime date) {
    final now = DateTime.now();
    return _isSameDay(date, now);
  }
  
  Color _getMaintenanceColor(MaintenanceDto maintenance) {
    // status 필드가 백엔드에 없으므로 날짜 기반으로 상태 계산
    final now = DateTime.now();
    String status;
    
    if (maintenance.isDeleted ?? false) {
      status = 'cancelled';
    } else if (maintenance.startedAt.isAfter(now)) {
      status = 'scheduled';
    } else if (maintenance.endedAt.isBefore(now)) {
      status = 'overdue';
    } else {
      status = 'in_progress';
    }
    
    switch (status.toLowerCase()) {
      case 'overdue':
        return Colors.red;
      case 'scheduled':
      case 'upcoming':
        // nextMaintenanceDate 필드가 없으므로 startedAt 기반으로 계산
        final daysUntil = maintenance.startedAt.difference(DateTime.now()).inDays;
        if (daysUntil <= 7) {
          return Colors.orange;
        } else if (daysUntil <= 30) {
          return Colors.yellow[700]!;
        }
        return Colors.blue;
      case 'inprogress':
      case 'ongoing':
        return Colors.purple;
      case 'completed':
        return Colors.green;
      default:
        return Colors.grey;
    }
  }
}