// 📅 백품타 출석 달력 화면 (UI 전용) - 개인 연속출석(스트릭) + 관리자 이벤트 달력.
// "실시간 출석 현황"과 같은 패밀리룩(제목 알약 + 필 통계 + 둥근 카드)을 따른다.
// 서버 통신/상태는 lib/function/study_calendar_controller.dart가 담당한다.
import 'package:flutter/material.dart';
import '../function/study_calendar_controller.dart';
import '../theme/app_palette.dart';
import 'app_notice.dart';
import 'title_pill.dart';

class StudyCalendarScreen extends StatefulWidget {
  final String studentId;
  final bool canManageEvents;

  const StudyCalendarScreen({
    super.key,
    required this.studentId,
    this.canManageEvents = false,
  });

  @override
  State<StudyCalendarScreen> createState() => _StudyCalendarScreenState();
}

class _StudyCalendarScreenState extends State<StudyCalendarScreen> {
  late final StudyCalendarController _controller;
  static const _weekdayLabels = ['일', '월', '화', '수', '목', '금', '토'];

  @override
  void initState() {
    super.initState();
    _controller = StudyCalendarController(studentId: widget.studentId);
    _controller.init();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

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

  Future<void> _onDayTap(DateTime day) async {
    final key = _dateKey(day);
    final event = _controller.events[key];

    if (!widget.canManageEvents) {
      if (event != null) {
        await showDialog<void>(
          context: context,
          builder: (dialogContext) => AlertDialog(
            title: Text(event['title'] ?? ''),
            content: Text(
              (event['description'] ?? '').toString().isEmpty
                  ? '등록된 설명이 없어요.'
                  : event['description'],
            ),
            actions: [
              TextButton(
                onPressed: () => Navigator.pop(dialogContext),
                child: const Text('닫기'),
              ),
            ],
          ),
        );
      }
      return;
    }

    final titleController = TextEditingController(text: event?['title'] ?? '');
    final descController = TextEditingController(
      text: event?['description'] ?? '',
    );

    await showModalBottomSheet<void>(
      context: context,
      isScrollControlled: true,
      backgroundColor: AppPalette.paper,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
      ),
      builder: (sheetContext) {
        return Padding(
          padding: EdgeInsets.only(
            left: 20,
            right: 20,
            top: 20,
            bottom: MediaQuery.of(sheetContext).viewInsets.bottom + 20,
          ),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Text(
                '$key 이벤트',
                style: const TextStyle(
                  fontWeight: FontWeight.bold,
                  fontSize: 16,
                ),
              ),
              const SizedBox(height: 12),
              TextField(
                controller: titleController,
                maxLength: 30,
                decoration: InputDecoration(
                  hintText: '제목 (예: 기프티콘 이벤트)',
                  filled: true,
                  fillColor: AppPalette.mist,
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(12),
                    borderSide: BorderSide.none,
                  ),
                ),
              ),
              TextField(
                controller: descController,
                maxLength: 100,
                maxLines: 3,
                decoration: InputDecoration(
                  hintText: '설명 (선택)',
                  filled: true,
                  fillColor: AppPalette.mist,
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(12),
                    borderSide: BorderSide.none,
                  ),
                ),
              ),
              const SizedBox(height: 12),
              Row(
                children: [
                  if (event != null)
                    Expanded(
                      child: OutlinedButton(
                        onPressed: () async {
                          final (success, message) = await _controller
                              .deleteEvent(key);
                          if (sheetContext.mounted) {
                            Navigator.of(sheetContext).pop();
                          }
                          if (!mounted) return;
                          AppNotice.show(context, message);
                        },
                        child: const Text(
                          '삭제',
                          style: TextStyle(color: Colors.red),
                        ),
                      ),
                    ),
                  if (event != null) const SizedBox(width: 8),
                  Expanded(
                    child: ElevatedButton(
                      style: ElevatedButton.styleFrom(
                        backgroundColor: AppPalette.ink,
                        foregroundColor: AppPalette.paper,
                      ),
                      onPressed: () async {
                        if (titleController.text.trim().isEmpty) return;
                        final (success, message) = await _controller.saveEvent(
                          date: key,
                          title: titleController.text,
                          description: descController.text,
                          createdBy: widget.studentId,
                        );
                        if (sheetContext.mounted) {
                          Navigator.of(sheetContext).pop();
                        }
                        if (!mounted) return;
                        AppNotice.show(
                          context,
                          message,
                          icon: success
                              ? Icons.check_circle_rounded
                              : Icons.error_outline_rounded,
                        );
                      },
                      child: const Text('저장'),
                    ),
                  ),
                ],
              ),
            ],
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: _controller,
      builder: (context, _) {
        final month = _controller.visibleMonth;
        final firstOfMonth = DateTime(month.year, month.month, 1);
        final daysInMonth = DateTime(month.year, month.month + 1, 0).day;
        final leadingBlanks = firstOfMonth.weekday % 7;
        final today = DateTime.now();

        return Scaffold(
          backgroundColor: AppPalette.mist,
          appBar: AppBar(
            backgroundColor: Colors.transparent,
            foregroundColor: AppPalette.ink,
            elevation: 0,
          ),
          body: _controller.isLoading
              ? const Center(child: CircularProgressIndicator())
              : ListView(
                  padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
                  children: [
                    const Center(child: TitlePill('출석 달력')),
                    const SizedBox(height: 16),
                    Row(
                      children: [
                        Expanded(
                          child: _statPill('연속 출석', _controller.currentStreak),
                        ),
                        const SizedBox(width: 8),
                        Expanded(
                          child: _statPill('최장 기록', _controller.longestStreak),
                        ),
                      ],
                    ),
                    const SizedBox(height: 20),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: [
                        IconButton(
                          icon: const Icon(Icons.chevron_left_rounded),
                          onPressed: _controller.goToPreviousMonth,
                        ),
                        Text(
                          '${month.year}년 ${month.month}월',
                          style: const TextStyle(
                            fontWeight: FontWeight.bold,
                            fontSize: 16,
                          ),
                        ),
                        IconButton(
                          icon: const Icon(Icons.chevron_right_rounded),
                          onPressed: _controller.goToNextMonth,
                        ),
                      ],
                    ),
                    const SizedBox(height: 8),
                    Row(
                      children: [
                        for (final label in _weekdayLabels)
                          Expanded(
                            child: Center(
                              child: Text(
                                label,
                                style: TextStyle(
                                  color: Colors.grey[500],
                                  fontSize: 12,
                                  fontWeight: FontWeight.bold,
                                ),
                              ),
                            ),
                          ),
                      ],
                    ),
                    const SizedBox(height: 6),
                    GridView.builder(
                      shrinkWrap: true,
                      physics: const NeverScrollableScrollPhysics(),
                      gridDelegate:
                          const SliverGridDelegateWithFixedCrossAxisCount(
                            crossAxisCount: 7,
                            mainAxisSpacing: 6,
                            crossAxisSpacing: 6,
                            childAspectRatio: 0.85,
                          ),
                      itemCount: leadingBlanks + daysInMonth,
                      itemBuilder: (context, index) {
                        if (index < leadingBlanks) {
                          return const SizedBox.shrink();
                        }
                        final day = index - leadingBlanks + 1;
                        final date = DateTime(month.year, month.month, day);
                        final key = _dateKey(date);
                        final studied = _controller.studiedDates.contains(key);
                        final event = _controller.events[key];
                        final isToday =
                            date.year == today.year &&
                            date.month == today.month &&
                            date.day == today.day;

                        return GestureDetector(
                          onTap: () => _onDayTap(date),
                          child: Container(
                            decoration: BoxDecoration(
                              color: studied
                                  ? AppPalette.ink
                                  : AppPalette.paper,
                              borderRadius: BorderRadius.circular(12),
                              border: Border.all(
                                color: isToday
                                    ? AppPalette.ink
                                    : AppPalette.sage,
                                width: isToday ? 2 : 1,
                              ),
                            ),
                            child: Stack(
                              children: [
                                Center(
                                  child: Text(
                                    '$day',
                                    style: TextStyle(
                                      fontWeight: FontWeight.bold,
                                      color: studied
                                          ? Colors.white
                                          : AppPalette.ink,
                                    ),
                                  ),
                                ),
                                if (event != null)
                                  Positioned(
                                    top: 3,
                                    right: 3,
                                    child: Icon(
                                      Icons.card_giftcard_rounded,
                                      size: 12,
                                      color: studied
                                          ? Colors.white
                                          : Colors.orange,
                                    ),
                                  ),
                              ],
                            ),
                          ),
                        );
                      },
                    ),
                    const SizedBox(height: 16),
                    Row(
                      children: [
                        _legendDot(AppPalette.ink, '공부한 날'),
                        const SizedBox(width: 16),
                        _legendIcon(
                          Icons.card_giftcard_rounded,
                          Colors.orange,
                          '이벤트',
                        ),
                      ],
                    ),
                  ],
                ),
        );
      },
    );
  }

  Widget _statPill(String label, int count) {
    return Container(
      padding: const EdgeInsets.symmetric(vertical: 14, horizontal: 16),
      decoration: BoxDecoration(
        color: AppPalette.paper,
        borderRadius: BorderRadius.circular(28),
        border: Border.all(color: AppPalette.sage),
      ),
      child: Column(
        children: [
          Text(label, style: TextStyle(fontSize: 12, color: Colors.grey[600])),
          const SizedBox(height: 4),
          Text(
            '$count일',
            style: const TextStyle(
              fontSize: 18,
              fontWeight: FontWeight.bold,
              color: AppPalette.ink,
            ),
          ),
        ],
      ),
    );
  }

  Widget _legendDot(Color color, String label) {
    return Row(
      children: [
        Container(
          width: 12,
          height: 12,
          decoration: BoxDecoration(color: color, shape: BoxShape.circle),
        ),
        const SizedBox(width: 6),
        Text(label, style: TextStyle(fontSize: 12, color: Colors.grey[600])),
      ],
    );
  }

  Widget _legendIcon(IconData icon, Color color, String label) {
    return Row(
      children: [
        Icon(icon, size: 14, color: color),
        const SizedBox(width: 6),
        Text(label, style: TextStyle(fontSize: 12, color: Colors.grey[600])),
      ],
    );
  }
}