import 'package:flutter/material.dart';

/// 树节点数据接口
abstract class TreeNode {
  String get id;
  String get name;
  bool get isExpanded;
  bool get isDirectory;
  List<TreeNode> get children;
  int get depth;
  IconData? get iconData;
}

/// 树视图配置
class TreeViewConfig {
  final bool lazyLoad;
  final bool singleSelect;
  final bool showCheckboxes;
  final bool showIcons;
  final Color? selectedColor;
  final double indentWidth;
  final Map<String, IconData> icons; // 改为final

  const TreeViewConfig({
    this.lazyLoad = false,
    this.singleSelect = false,
    this.showCheckboxes = false,
    this.showIcons = true,
    this.selectedColor,
    this.indentWidth = 24.0,
    this.icons = const {}, // 提供空Map作为默认值
  });
}

/// 通用树视图组件
class TreeView extends StatefulWidget {
  final List<TreeNode> nodes;
  final TreeViewConfig config;
  final Function(TreeNode)? onNodeTap;
  final Function(TreeNode)? onNodeDoubleTap;
  final Function(TreeNode, bool?)? onNodeCheckChanged;
  final Widget Function(BuildContext, TreeNode, bool, VoidCallback)? nodeBuilder; // 新增参数
  final ScrollController? scrollController;

  const TreeView({
    super.key,
    required this.nodes,
    this.config = const TreeViewConfig(),
    this.onNodeTap,
    this.onNodeDoubleTap,
    this.onNodeCheckChanged,
    this.nodeBuilder,
    this.scrollController,
  });

  @override
  State<TreeView> createState() => _TreeViewState();
}

class _TreeViewState extends State<TreeView> {
  final Set<String> _selectedIds = {};
  final Set<String> _checkedIds = {};
  late ScrollController _effectiveController;

  @override
  void initState() {
    super.initState();
    _effectiveController = widget.scrollController ?? ScrollController();
  }

  @override
  void didUpdateWidget(TreeView oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.scrollController != oldWidget.scrollController) {
      if (oldWidget.scrollController == null) {
        _effectiveController.dispose();
      }
      _effectiveController = widget.scrollController ?? ScrollController();
    }
  }

  @override
  void dispose() {
    if (widget.scrollController == null) {
      _effectiveController.dispose();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      controller: _effectiveController,
      physics: const ClampingScrollPhysics(),
      itemCount: _countVisibleNodes(widget.nodes),
      itemBuilder: (context, index) {
        final node = _getVisibleNode(widget.nodes, index);
        final isSelected = _selectedIds.contains(node.id);

        // 使用自定义构建器或默认构建器
        return widget.nodeBuilder != null
            ? widget.nodeBuilder!(context, node, isSelected, () => _handleNodeTap(node))
            : TreeNodeWidget(
              node: node,
              config: widget.config,
              isSelected: isSelected,
              isChecked: _checkedIds.contains(node.id),
              onTap: () => _handleNodeTap(node),
              onDoubleTap: () => widget.onNodeDoubleTap?.call(node),
              onCheckChanged: (value) => _handleNodeCheckChanged(node, value),
            );
      },
    );
  }

  void _handleNodeTap(TreeNode node) {
    if (widget.config.singleSelect && !node.isDirectory) {
      // 只处理叶子节点的单选逻辑
      setState(() {
        _selectedIds.clear();
        _selectedIds.add(node.id);
      });
    }

    widget.onNodeTap?.call(node);
  }

  void _handleNodeCheckChanged(TreeNode node, bool? value) {
    setState(() {
      if (value == true) {
        _checkedIds.add(node.id);
      } else {
        _checkedIds.remove(node.id);
      }
    });

    widget.onNodeCheckChanged?.call(node, value);
  }

  int _countVisibleNodes(List<TreeNode> nodes) {
    int count = 0;
    for (final node in nodes) {
      count++;
      if (node.isDirectory && node.isExpanded) {
        count += _countVisibleNodes(node.children);
      }
    }
    return count;
  }

  TreeNode _getVisibleNode(List<TreeNode> nodes, int index) {
    int current = 0;
    for (final node in nodes) {
      if (current == index) return node;
      current++;
      if (node.isDirectory && node.isExpanded) {
        final childCount = _countVisibleNodes(node.children);
        if (index - current < childCount) {
          return _getVisibleNode(node.children, index - current);
        }
        current += childCount;
      }
    }
    throw Exception('Index out of bounds: $index');
  }
}

class TreeNodeWidget extends StatelessWidget {
  final TreeNode node;
  final TreeViewConfig config;
  final bool isSelected;
  final bool isChecked;
  final VoidCallback onTap;
  final VoidCallback onDoubleTap;
  final Function(bool?)? onCheckChanged;

  const TreeNodeWidget({
    required this.node,
    required this.config,
    required this.isSelected,
    required this.isChecked,
    required this.onTap,
    required this.onDoubleTap,
    this.onCheckChanged,
  });

  @override
  Widget build(BuildContext context) {
    return InkWell(
      onTap: onTap,
      onDoubleTap: onDoubleTap,
      splashColor: Colors.transparent,
      highlightColor: Colors.grey.withOpacity(0.1),
      child: Container(
        color:
            isSelected
                ? (config.selectedColor ?? Theme.of(context).primaryColor.withOpacity(0.1))
                : Colors.transparent,
        padding: const EdgeInsets.symmetric(vertical: 0),
        child: ListTile(
          dense: true,
          visualDensity: const VisualDensity(vertical: -4),
          contentPadding: const EdgeInsets.symmetric(horizontal: 2),
          minVerticalPadding: 0,
          leading: _buildLeadingWidget(context),
          title: Text(node.name, style: Theme.of(context).textTheme.bodyMedium),
          trailing:
              config.showCheckboxes
                  ? Checkbox(
                    value: isChecked,
                    onChanged: onCheckChanged,
                    materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                  )
                  : null,
        ),
      ),
    );
  }

  Widget _buildLeadingWidget(BuildContext context) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        // 缩进线
        ...List.generate(node.depth, (index) {
          return Padding(
            padding: EdgeInsets.only(left: 6, right: config.indentWidth - 6),
            child: Container(width: 1.0, height: 32.0, color: Colors.grey[500]),
          );
        }),

        // 展开/折叠图标
        if (node.isDirectory)
          Icon(
            node.isExpanded ? Icons.expand_more : Icons.chevron_right,
            color: Colors.cyan[200],
            size: 20,
          ),

        // 节点图标
        if (config.showIcons)
          node.isDirectory
              ? Icon(
                node.isExpanded ? Icons.folder_open : Icons.folder,
                color: Colors.cyan[500],
                size: 18,
              )
              : Icon(node.iconData ?? Icons.insert_drive_file, color: Colors.amber[700], size: 20),
      ],
    );
  }
}