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/router/app_routes.dart';
import '../../../../core/theme/design_tokens.dart';
import '../../../home/ui/navigation/home_return_policy.dart';
import '../../../../shared/widgets/app_pull_refresh_feedback.dart';
import '../../../../shared/widgets/app_pressable.dart';
import '../../../../shared/widgets/back_title_page_header.dart';
import '../../../../shared/widgets/error_retry_surface.dart';
import '../../../../shared/widgets/full_screen_loading.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';
import '../../../calendar/ui/calendar_state_manager.dart';
import '../../../calendar/ui/widgets/bottom_dock.dart';
import '../../data/todo_api.dart';
import '../widgets/todo_drag_item.dart';

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

  @override
  State<TodoQuadrantsScreen> createState() => _TodoQuadrantsScreenState();
}

class _TodoQuadrantsScreenState extends State<TodoQuadrantsScreen> {
  final TodoApi _todoApi = sl<TodoApi>();

  List<TodoResponse> _todos = [];
  bool _isLoading = true;
  bool _isPullRefreshing = false;
  bool _loadingTodosRequest = false;
  String? _error;

  String? _draggingTodoId;
  int? _dragTargetQuadrant;
  int? _dragInsertIndex;

  bool get _isDragging => _draggingTodoId != null;

  void _onDragStart(String todoId) {
    setState(() {
      _draggingTodoId = todoId;
      _dragTargetQuadrant = null;
      _dragInsertIndex = null;
    });
  }

  void _onDragEnd() {
    setState(() {
      _draggingTodoId = null;
      _dragTargetQuadrant = null;
      _dragInsertIndex = null;
    });
  }

  void _onDragEnterQuadrant(int quadrant) {
    setState(() {
      _dragTargetQuadrant = quadrant;
    });
  }

  void _onDragUpdateInsertIndex(int index) {
    setState(() {
      _dragInsertIndex = index;
    });
  }

  Future<void> _onDrop(
    String todoId,
    int targetQuadrant,
    int insertIndex,
  ) async {
    final previousTodos = List<TodoResponse>.from(_todos);
    try {
      final todo = _todos.firstWhere((t) => t.id == todoId);
      final sourceQuadrant = todo.priority;

      if (sourceQuadrant == targetQuadrant) {
        _onDragEnd();
        return;
      }

      setState(() {
        final index = _todos.indexWhere((t) => t.id == todoId);
        if (index != -1) {
          _todos[index] = _todos[index].copyWith(priority: targetQuadrant);
        }
      });

      await _todoApi.updateTodoPriority(todoId, targetQuadrant);
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _todos = previousTodos;
      });
      Toast.show(context, '移动失败', type: ToastType.error);
    } finally {
      if (mounted) _onDragEnd();
    }
  }

  void _onDragLeave() {
    // 清除高亮
  }

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

  Future<void> _loadTodos({bool showPageLoader = true}) async {
    if (_loadingTodosRequest || _isPullRefreshing) {
      return;
    }
    _loadingTodosRequest = true;

    setState(() {
      if (showPageLoader) {
        _isLoading = true;
        _error = null;
      } else {
        _isPullRefreshing = true;
      }
    });

    try {
      final todos = await _todoApi.getTodos(status: 'pending');
      if (!mounted) {
        return;
      }
      setState(() {
        _todos = todos;
        _isLoading = false;
        _isPullRefreshing = false;
        _error = null;
      });
    } catch (e) {
      if (!mounted) {
        return;
      }
      if (showPageLoader) {
        setState(() {
          _error = e.toString();
          _isLoading = false;
          _isPullRefreshing = false;
        });
      } else {
        setState(() => _isPullRefreshing = false);
        Toast.show(context, '刷新失败，请稍后重试', type: ToastType.error);
      }
    } finally {
      _loadingTodosRequest = false;
    }
  }

  Future<void> _onPullRefresh() async {
    await _loadTodos(showPageLoader: false);
  }

  List<TodoResponse> get _importantUrgent =>
      _todos.where((t) => t.priority == 1).toList();

  List<TodoResponse> get _urgentNotImportant =>
      _todos.where((t) => t.priority == 3).toList();

  List<TodoResponse> get _importantNotUrgent =>
      _todos.where((t) => t.priority == 2).toList();

  Future<void> _completeTodo(TodoResponse todo) async {
    try {
      await _todoApi.completeTodo(todo.id);
      if (mounted) {
        Toast.show(context, '已完成', type: ToastType.success);
      }
      try {
        await _loadTodos();
      } catch (_) {
        // ignore reload error
      }
    } catch (e) {
      if (mounted) {
        Toast.show(context, '完成失败: $e', type: ToastType.error);
      }
    }
  }

  void _navigateToDetail(TodoResponse todo) {
    context.push(AppRoutes.todoDetail(todo.id));
  }

  Future<void> _addTodo() async {
    final created = await context.push<bool>(AppRoutes.todoCreate);
    if (created == true) {
      await _loadTodos();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.todoBg,
      body: PopScope(
        canPop: false,
        onPopInvokedWithResult: (didPop, result) {
          if (!didPop) {
            returnToHomePreserveState(context);
          }
        },
        child: SafeArea(
          child: Column(
            children: [
              _buildHeader(),
              Expanded(child: _buildContent(withScroll: true)),
              _buildBottomDock(),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return BackTitlePageHeader(
      title: '待办事项',
      showBackButton: false,
      trailing: Row(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          AppPressable(
            borderRadius: BorderRadius.circular(AppRadius.full),
            onTap: _loadTodos,
            child: Container(
              width: 36,
              height: 36,
              decoration: BoxDecoration(
                color: AppColors.messageBtnWrap,
                borderRadius: BorderRadius.circular(AppRadius.full),
                border: Border.all(color: AppColors.messageBtnBorder),
              ),
              child: const Icon(
                LucideIcons.refreshCcw,
                size: 18,
                color: AppColors.slate600,
              ),
            ),
          ),
          const SizedBox(width: AppSpacing.sm),
          AppPressable(
            borderRadius: BorderRadius.circular(AppRadius.full),
            onTap: _addTodo,
            child: Container(
              width: 36,
              height: 36,
              decoration: BoxDecoration(
                color: AppColors.blue600,
                borderRadius: BorderRadius.circular(AppRadius.full),
                boxShadow: [
                  BoxShadow(
                    color: AppColors.blue300.withValues(alpha: 0.28),
                    blurRadius: AppRadius.lg,
                    offset: const Offset(0, AppSpacing.xs),
                  ),
                ],
              ),
              child: const Icon(
                LucideIcons.plus,
                size: 18,
                color: AppColors.white,
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildContent({bool withScroll = false}) {
    if (_isLoading) {
      return const FullScreenLoading();
    }

    if (_error != null) {
      return ErrorRetrySurface(message: '加载失败: $_error', onRetry: _loadTodos);
    }

    Widget content = Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        _buildQuadrant(
          title: '重要紧急',
          textColor: AppColors.g1Text,
          dividerColor: AppColors.g1Divider,
          borderColor: AppColors.g1Border,
          items: _importantUrgent,
          quadrantValue: 1,
          onComplete: _completeTodo,
          onTap: _navigateToDetail,
        ),
        const SizedBox(height: 12),
        _buildQuadrant(
          title: '紧急不重要',
          textColor: AppColors.g2Text,
          dividerColor: AppColors.g2Divider,
          borderColor: AppColors.g2Border,
          items: _urgentNotImportant,
          quadrantValue: 3,
          onComplete: _completeTodo,
          onTap: _navigateToDetail,
        ),
        const SizedBox(height: 12),
        _buildQuadrant(
          title: '重要不紧急',
          textColor: AppColors.g3Text,
          dividerColor: AppColors.g3Divider,
          borderColor: AppColors.g3Border,
          items: _importantNotUrgent,
          quadrantValue: 2,
          onComplete: _completeTodo,
          onTap: _navigateToDetail,
        ),
      ],
    );

    if (withScroll) {
      return Stack(
        children: [
          RefreshIndicator.noSpinner(
            onRefresh: _onPullRefresh,
            child: SingleChildScrollView(
              padding: const EdgeInsets.only(
                left: 16,
                right: 16,
                top: 4,
                bottom: 96,
              ),
              child: content,
            ),
          ),
          Align(
            alignment: Alignment.topCenter,
            child: AppPullRefreshFeedback(visible: _isPullRefreshing),
          ),
        ],
      );
    }

    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 4, 16, 16),
      child: content,
    );
  }

  Widget _buildQuadrant({
    required String title,
    required Color textColor,
    required Color dividerColor,
    required Color borderColor,
    required List<TodoResponse> items,
    required int quadrantValue,
    required Future<void> Function(TodoResponse) onComplete,
    required void Function(TodoResponse) onTap,
  }) {
    return Container(
      decoration: BoxDecoration(
        color: AppColors.todoCardBg,
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: borderColor, width: 1),
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _buildQuadrantHeader(title, textColor, items.length),
          Container(height: 1, color: dividerColor),
          const SizedBox(height: 8),
          Padding(
            padding: const EdgeInsets.fromLTRB(6, 0, 6, 8),
            child: DragTarget<String>(
              onWillAcceptWithDetails: (details) {
                _onDragEnterQuadrant(quadrantValue);
                return true;
              },
              onAcceptWithDetails: (details) {
                final parts = details.data.split(':');
                final todoId = parts[0];
                _onDrop(todoId, quadrantValue, 0);
              },
              onLeave: (_) {
                _onDragLeave();
              },
              builder: (context, candidateData, rejectedData) {
                final isDragOver = candidateData.isNotEmpty;
                return Container(
                  decoration: BoxDecoration(
                    color: isDragOver
                        ? AppColors.blue50.withValues(alpha: 0.3)
                        : Colors.transparent,
                    borderRadius: BorderRadius.circular(8),
                    border: isDragOver
                        ? Border.all(color: AppColors.blue400, width: 2)
                        : null,
                  ),
                  child: items.isEmpty
                      ? SizedBox(
                          height: 60,
                          child: Center(
                            child: Text(
                              '暂无待办',
                              style: TextStyle(
                                fontFamily: 'Inter',
                                fontSize: 13,
                                color: AppColors.slate400,
                              ),
                            ),
                          ),
                        )
                      : _buildQuadrantItemList(
                          items,
                          quadrantValue,
                          onComplete,
                          onTap,
                        ),
                );
              },
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildQuadrantHeader(String title, Color textColor, int itemCount) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(10, 10, 10, 8),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text(
            title,
            style: TextStyle(
              fontFamily: 'Inter',
              fontSize: 15,
              fontWeight: FontWeight.w700,
              color: textColor,
            ),
          ),
          Text(
            '${itemCount}项',
            style: TextStyle(
              fontFamily: 'Inter',
              fontSize: 12,
              fontWeight: FontWeight.w700,
              color: textColor,
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildQuadrantItemList(
    List<TodoResponse> items,
    int quadrantValue,
    Future<void> Function(TodoResponse) onComplete,
    void Function(TodoResponse) onTap,
  ) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: items.map((item) {
        return TodoDragItem(
          todo: item,
          quadrant: quadrantValue,
          onDragStarted: () => _onDragStart(item.id),
          onDragEnd: _onDragEnd,
          child: _TodoItemWidget(
            item: item,
            onComplete: () => onComplete(item),
            onTap: () => onTap(item),
          ),
        );
      }).toList(),
    );
  }

  Widget _buildBottomDock() {
    return BottomDock(
      activeTab: DockTab.todo,
      onTodoTap: () {},
      onCalendarTap: () {
        final manager = sl<CalendarStateManager>();
        final viewType = manager.viewType;
        final date = manager.selectedDate;
        final dateStr =
            '${date.year}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}';
        if (viewType == CalendarViewType.month) {
          context.push(AppRoutes.calendarMonth);
        } else {
          context.push('${AppRoutes.calendarDayWeek}?date=$dateStr');
        }
      },
      onHomeTap: () => returnToHomePreserveState(context),
    );
  }
}

class _TodoItemWidget extends StatefulWidget {
  final TodoResponse item;
  final VoidCallback onComplete;
  final VoidCallback onTap;

  const _TodoItemWidget({
    required this.item,
    required this.onComplete,
    required this.onTap,
  });

  @override
  State<_TodoItemWidget> createState() => _TodoItemWidgetState();
}

class _TodoItemWidgetState extends State<_TodoItemWidget>
    with SingleTickerProviderStateMixin {
  bool _isChecked = false;
  late AnimationController _controller;
  late Animation<double> _scaleAnimation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(milliseconds: 200),
      vsync: this,
    );
    _scaleAnimation = Tween<double>(
      begin: 0.0,
      end: 1.0,
    ).animate(CurvedAnimation(parent: _controller, curve: Curves.easeOutBack));
  }

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

  void _handleCheckTap() async {
    if (_isChecked) return;

    setState(() {
      _isChecked = true;
    });
    _controller.forward().then((_) {
      widget.onComplete();
    });
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: widget.onTap,
      child: SizedBox(
        height: 42,
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: [
            Expanded(
              child: Text(
                widget.item.title,
                style: const TextStyle(
                  fontFamily: 'Inter',
                  fontSize: 13,
                  fontWeight: FontWeight.w600,
                  color: AppColors.slate700,
                ),
              ),
            ),
            GestureDetector(
              onTap: _handleCheckTap,
              child: AnimatedBuilder(
                animation: _controller,
                builder: (context, child) {
                  return Container(
                    width: 20,
                    height: 20,
                    decoration: BoxDecoration(
                      color: _isChecked ? AppColors.blue600 : Colors.white,
                      border: Border.all(
                        color: _isChecked
                            ? AppColors.blue600
                            : AppColors.slate300,
                        width: 1.5,
                      ),
                      borderRadius: BorderRadius.circular(4),
                    ),
                    child: _isChecked
                        ? Transform.scale(
                            scale: _scaleAnimation.value,
                            child: const Icon(
                              Icons.check,
                              size: 14,
                              color: Colors.white,
                            ),
                          )
                        : null,
                  );
                },
              ),
            ),
          ],
        ),
      ),
    );
  }
}