import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:lucide_icons/lucide_icons.dart';
import '../../../../core/di/injection.dart';
import '../../../../core/theme/design_tokens.dart';
import '../../../../shared/widgets/page_header.dart' as widgets;
import '../../../../shared/widgets/app_button.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';
import '../../../calendar/data/calendar_api.dart';
import '../../data/todo_api.dart';

class TodoDetailScreen extends StatefulWidget {
  final String todoId;

  const TodoDetailScreen({super.key, required this.todoId});

  @override
  State<TodoDetailScreen> createState() => _TodoDetailScreenState();
}

class _TodoDetailScreenState extends State<TodoDetailScreen> {
  final TodoApi _todoApi = sl<TodoApi>();

  TodoResponse? _todo;
  bool _isLoading = true;
  String? _error;

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

  Future<void> _loadTodo() async {
    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final todo = await _todoApi.getTodo(widget.todoId);
      setState(() {
        _todo = todo;
        _isLoading = false;
      });
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  String _getPriorityLabel(int priority) {
    switch (priority) {
      case 1:
        return '重要紧急';
      case 2:
        return '重要不紧急';
      case 3:
        return '紧急不重要';
      case 4:
        return '不紧急不重要';
      default:
        return '未知';
    }
  }

  Color _getPriorityColor(int priority) {
    switch (priority) {
      case 1:
        return AppColors.g1Text;
      case 2:
        return AppColors.g3Text;
      case 3:
        return AppColors.g2Text;
      default:
        return AppColors.slate500;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.todoBg,
      body: SafeArea(
        child: Column(
          children: [
            _buildHeader(context),
            Expanded(child: _buildContent()),
          ],
        ),
      ),
    );
  }

  Widget _buildHeader(BuildContext context) {
    return SizedBox(
      height: 64,
      child: Padding(
        padding: const EdgeInsets.only(left: 16, right: 16, top: 12, bottom: 8),
        child: Row(
          children: [
            widgets.BackButton(onPressed: () => Navigator.of(context).pop()),
            const Spacer(),
            if (_todo != null) ...[
              IconButton(
                onPressed: _editTodo,
                icon: const Icon(
                  LucideIcons.pencil,
                  size: 20,
                  color: AppColors.slate600,
                ),
              ),
              IconButton(
                onPressed: _deleteTodo,
                icon: const Icon(
                  LucideIcons.trash2,
                  size: 20,
                  color: Colors.red,
                ),
              ),
            ],
          ],
        ),
      ),
    );
  }

  Widget _buildContent() {
    if (_isLoading) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_error != null) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('加载失败: $_error', style: const TextStyle(color: Colors.red)),
            const SizedBox(height: 16),
            AppButton(text: '重试', onPressed: _loadTodo),
          ],
        ),
      );
    }

    if (_todo == null) {
      return const Center(child: Text('待办不存在'));
    }

    return Padding(
      padding: const EdgeInsets.only(left: 16, right: 16, top: 4, bottom: 20),
      child: ListView(
        children: [
          _buildMainCard(),
          const SizedBox(height: 12),
          if (_todo!.scheduleItems.isNotEmpty) ...[
            Text(
              '日历事件卡片',
              style: TextStyle(
                fontFamily: 'Inter',
                fontSize: 12,
                fontWeight: FontWeight.w500,
                color: AppColors.slate500,
              ),
            ),
            const SizedBox(height: 10),
            ..._todo!.scheduleItems.map(
              (item) => _buildEventCard(
                id: item.id,
                title: item.title,
                time: _formatEventTime(item.startAt, item.endAt),
                borderColor: AppColors.todoEventBorder1,
                onTap: () => context.push('/calendar/events/${item.id}'),
              ),
            ),
          ],
        ],
      ),
    );
  }

  String _formatEventTime(DateTime start, DateTime? end) {
    final startStr =
        '${start.year}年${start.month}月${start.day}日 ${start.hour.toString().padLeft(2, '0')}:${start.minute.toString().padLeft(2, '0')}';
    if (end != null) {
      final endStr =
          '${end.hour.toString().padLeft(2, '0')}:${end.minute.toString().padLeft(2, '0')}';
      return '$startStr - $endStr';
    }
    return startStr;
  }

  Widget _buildMainCard() {
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: AppColors.todoCardBg,
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: AppColors.todoDetailCardBorder, width: 1),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            _todo!.title,
            style: const TextStyle(
              fontFamily: 'Inter',
              fontSize: 18,
              fontWeight: FontWeight.w700,
              color: AppColors.slate900,
            ),
          ),
          const SizedBox(height: 4),
          Text(
            _buildSubtitle(),
            style: const TextStyle(
              fontFamily: 'Inter',
              fontSize: 12,
              fontWeight: FontWeight.w500,
              color: AppColors.slate500,
            ),
          ),
          if (_todo!.description != null && _todo!.description!.isNotEmpty) ...[
            const SizedBox(height: 8),
            Text(
              _todo!.description!,
              style: const TextStyle(
                fontFamily: 'Inter',
                fontSize: 13,
                color: AppColors.slate600,
              ),
            ),
          ],
          const SizedBox(height: 8),
          Container(height: 1, color: AppColors.border),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: '所属象限',
            value: _getPriorityLabel(_todo!.priority),
            valueColor: _getPriorityColor(_todo!.priority),
          ),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: '关联日历事件',
            value: '${_todo!.scheduleItems.length}个',
            valueColor: AppColors.g3Text,
          ),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: '状态',
            value: _todo!.status == 'done' ? '已完成' : '进行中',
            valueColor: _todo!.status == 'done'
                ? AppColors.success
                : AppColors.blue600,
          ),
        ],
      ),
    );
  }

  String _buildSubtitle() {
    final parts = <String>[];
    if (_todo!.dueAt != null) {
      final due = _todo!.dueAt!;
      parts.add(
        '截止 ${due.month}月${due.day}日 ${due.hour.toString().padLeft(2, '0')}:${due.minute.toString().padLeft(2, '0')}',
      );
    }
    if (_todo!.scheduleItems.isNotEmpty) {
      parts.add('已拆分为${_todo!.scheduleItems.length}个日历事件');
    } else {
      parts.add('未关联日历事件');
    }
    return parts.join(' · ');
  }

  Widget _buildInfoRow({
    required String label,
    required String value,
    required Color valueColor,
  }) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: [
        Text(
          label,
          style: const TextStyle(
            fontFamily: 'Inter',
            fontSize: 12,
            fontWeight: FontWeight.w600,
            color: AppColors.slate400,
          ),
        ),
        Text(
          value,
          style: TextStyle(
            fontFamily: 'Inter',
            fontSize: 12,
            fontWeight: FontWeight.w700,
            color: valueColor,
          ),
        ),
      ],
    );
  }

  Widget _buildEventCard({
    required String id,
    required String title,
    required String time,
    required Color borderColor,
    VoidCallback? onTap,
  }) {
    return GestureDetector(
      onTap: onTap,
      child: Container(
        width: double.infinity,
        padding: const EdgeInsets.all(10),
        margin: const EdgeInsets.only(bottom: 10),
        decoration: BoxDecoration(
          color: AppColors.todoCardBg,
          borderRadius: BorderRadius.circular(14),
          border: Border.all(color: borderColor, width: 1),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: const TextStyle(
                fontFamily: 'Inter',
                fontSize: 13,
                fontWeight: FontWeight.w600,
                color: AppColors.slate700,
              ),
            ),
            const SizedBox(height: 8),
            Text(
              time,
              style: const TextStyle(
                fontFamily: 'Inter',
                fontSize: 12,
                fontWeight: FontWeight.w500,
                color: AppColors.slate500,
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _editTodo() async {
    final result = await showModalBottomSheet<Map<String, dynamic>>(
      context: context,
      isScrollControlled: true,
      backgroundColor: Colors.transparent,
      builder: (context) => _EditTodoSheet(todo: _todo!),
    );

    if (result != null) {
      try {
        await _todoApi.updateTodo(
          _todo!.id,
          title: result['title'] as String,
          description: result['description'] as String?,
          priority: result['priority'] as int,
          scheduleItemIds: result['schedule_item_ids'] as List<String>?,
        );
        await _loadTodo();
      } catch (e) {
        if (mounted) {
          Toast.show(context, '更新失败: $e', type: ToastType.error);
        }
      }
    }
  }

  void _deleteTodo() async {
    final confirm = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('确认删除'),
        content: const Text('确定要删除这个待办吗？'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('取消'),
          ),
          TextButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('删除', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );

    if (confirm == true) {
      try {
        await _todoApi.deleteTodo(_todo!.id);
        if (mounted) {
          context.pop();
        }
      } catch (e) {
        if (mounted) {
          Toast.show(context, '删除失败: $e', type: ToastType.error);
        }
      }
    }
  }
}

class _EditTodoSheet extends StatefulWidget {
  final TodoResponse todo;

  const _EditTodoSheet({required this.todo});

  @override
  State<_EditTodoSheet> createState() => _EditTodoSheetState();
}

class _EditTodoSheetState extends State<_EditTodoSheet> {
  late TextEditingController _titleController;
  late TextEditingController _descriptionController;
  late int _priority;
  late Set<String> _selectedScheduleItems;

  @override
  void initState() {
    super.initState();
    _titleController = TextEditingController(text: widget.todo.title);
    _descriptionController = TextEditingController(
      text: widget.todo.description ?? '',
    );
    _priority = widget.todo.priority;
    _selectedScheduleItems = widget.todo.scheduleItems.map((e) => e.id).toSet();
  }

  @override
  void dispose() {
    _titleController.dispose();
    _descriptionController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      height: MediaQuery.of(context).size.height * 0.85,
      decoration: const BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
      ),
      child: Column(
        children: [
          SingleChildScrollView(
            padding: const EdgeInsets.all(24),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    const Text(
                      '编辑待办',
                      style: TextStyle(
                        fontFamily: 'Inter',
                        fontSize: 20,
                        fontWeight: FontWeight.w700,
                      ),
                    ),
                    IconButton(
                      onPressed: () => Navigator.of(context).pop(),
                      icon: const Icon(LucideIcons.x),
                    ),
                  ],
                ),
                const SizedBox(height: 20),
                TextField(
                  controller: _titleController,
                  decoration: const InputDecoration(
                    labelText: '标题',
                    border: OutlineInputBorder(),
                  ),
                ),
                const SizedBox(height: 16),
                TextField(
                  controller: _descriptionController,
                  decoration: const InputDecoration(
                    labelText: '描述（可选）',
                    border: OutlineInputBorder(),
                  ),
                  maxLines: 2,
                ),
                const SizedBox(height: 16),
                const Text(
                  '优先级',
                  style: TextStyle(
                    fontFamily: 'Inter',
                    fontSize: 14,
                    fontWeight: FontWeight.w600,
                  ),
                ),
                const SizedBox(height: 8),
                Row(
                  children: [
                    _PriorityChip(
                      label: '重要紧急',
                      selected: _priority == 1,
                      color: AppColors.g1Border,
                      onTap: () => setState(() => _priority = 1),
                    ),
                    const SizedBox(width: 8),
                    _PriorityChip(
                      label: '紧急不重要',
                      selected: _priority == 3,
                      color: AppColors.g2Border,
                      onTap: () => setState(() => _priority = 3),
                    ),
                    const SizedBox(width: 8),
                    _PriorityChip(
                      label: '重要不紧急',
                      selected: _priority == 2,
                      color: AppColors.g3Border,
                      onTap: () => setState(() => _priority = 2),
                    ),
                  ],
                ),
              ],
            ),
          ),
          Expanded(
            child: FutureBuilder(
              future: _loadScheduleItems(),
              builder: (context, snapshot) {
                if (snapshot.connectionState == ConnectionState.waiting) {
                  return const Center(child: CircularProgressIndicator());
                }
                if (snapshot.hasError) {
                  return Center(child: Text('加载失败: ${snapshot.error}'));
                }
                final items = snapshot.data ?? [];
                if (items.isEmpty) {
                  return const Center(child: Text('暂无日历事件'));
                }
                return ListView.builder(
                  padding: const EdgeInsets.symmetric(horizontal: 16),
                  itemCount: items.length,
                  itemBuilder: (context, index) {
                    final item = items[index];
                    final isSelected = _selectedScheduleItems.contains(item.id);
                    return CheckboxListTile(
                      title: Text(item.title),
                      subtitle: Text(_formatDate(item.startAt)),
                      value: isSelected,
                      onChanged: (value) {
                        setState(() {
                          if (value == true) {
                            _selectedScheduleItems.add(item.id);
                          } else {
                            _selectedScheduleItems.remove(item.id);
                          }
                        });
                      },
                    );
                  },
                );
              },
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(16),
            child: SizedBox(
              width: double.infinity,
              child: AppButton(
                text: '保存',
                onPressed: () {
                  if (_titleController.text.trim().isEmpty) {
                    Toast.show(context, '请输入标题', type: ToastType.warning);
                    return;
                  }
                  Navigator.of(context).pop({
                    'title': _titleController.text.trim(),
                    'description': _descriptionController.text.trim().isEmpty
                        ? null
                        : _descriptionController.text.trim(),
                    'priority': _priority,
                    'schedule_item_ids': _selectedScheduleItems.toList(),
                  });
                },
              ),
            ),
          ),
        ],
      ),
    );
  }

  Future<List<_ScheduleItemSimple>> _loadScheduleItems() async {
    final calendarApi = sl<CalendarApi>();
    final now = DateTime.now();
    final start = now.subtract(const Duration(days: 30));
    final end = now.add(const Duration(days: 90));
    final items = await calendarApi.listByRange(startAt: start, endAt: end);
    return items
        .map(
          (e) =>
              _ScheduleItemSimple(id: e.id, title: e.title, startAt: e.startAt),
        )
        .toList();
  }

  String _formatDate(DateTime dt) {
    return '${dt.year}年${dt.month}月${dt.day}日 ${dt.hour.toString().padLeft(2, '0')}:${dt.minute.toString().padLeft(2, '0')}';
  }
}

class _ScheduleItemSimple {
  final String id;
  final String title;
  final DateTime startAt;

  _ScheduleItemSimple({
    required this.id,
    required this.title,
    required this.startAt,
  });
}

class _PriorityChip extends StatelessWidget {
  final String label;
  final bool selected;
  final Color color;
  final VoidCallback onTap;

  const _PriorityChip({
    required this.label,
    required this.selected,
    required this.color,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: onTap,
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
        decoration: BoxDecoration(
          color: selected ? color.withValues(alpha: 0.2) : Colors.transparent,
          border: Border.all(
            color: selected ? color : AppColors.slate300,
            width: selected ? 2 : 1,
          ),
          borderRadius: BorderRadius.circular(20),
        ),
        child: Text(
          label,
          style: TextStyle(
            fontFamily: 'Inter',
            fontSize: 12,
            fontWeight: selected ? FontWeight.w600 : FontWeight.normal,
            color: selected ? color : AppColors.slate600,
          ),
        ),
      ),
    );
  }
}