import 'package:flutter/material.dart';

import '../../models/note.dart';
import '../../widgets/cute_icon.dart';

/// 目录选择面板
///
/// 从底部弹出，展示「全部 / 未分类 / 目录树」三层结构。
/// 选中后 pop 出对应的 [NoteLocation]；直接关掉则返回 null。
class FolderPickerSheet extends StatefulWidget {
  const FolderPickerSheet({
    super.key,
    required this.tree,
    required this.current,
    this.title = '选择目录',
    this.showAll = true,
  });

  final FolderTree tree;
  final NoteLocation current;
  final String title;

  /// 是否显示「全部」这一项。
  /// 给笔记选目标目录时要关掉 —— 「全部」不是一个能存放笔记的位置。
  final bool showAll;

  /// 弹出面板的便捷方法
  static Future<NoteLocation?> show(
    BuildContext context, {
    required FolderTree tree,
    required NoteLocation current,
    String title = '选择目录',
    bool showAll = true,
  }) {
    return showModalBottomSheet<NoteLocation>(
      context: context,
      backgroundColor: Colors.white,
      isScrollControlled: true,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
      ),
      builder: (_) => FolderPickerSheet(
        tree: tree,
        current: current,
        title: title,
        showAll: showAll,
      ),
    );
  }

  @override
  State<FolderPickerSheet> createState() => _FolderPickerSheetState();
}

class _FolderPickerSheetState extends State<FolderPickerSheet> {
  final Set<int> _expanded = {};

  @override
  void initState() {
    super.initState();
    // 默认展开当前所在目录的所有上级，用户一眼能看到自己在哪
    if (widget.current.scope == NoteScope.folder && widget.current.folderId != null) {
      final path = widget.tree.findPath(widget.current.folderId!);
      if (path != null) {
        for (final node in path) {
          _expanded.add(node.id);
        }
      }
    }
  }

  bool _isCurrent(NoteScope scope, int? folderId) {
    if (widget.current.scope != scope) return false;
    if (scope != NoteScope.folder) return true;
    return widget.current.folderId == folderId;
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: ConstrainedBox(
        constraints: BoxConstraints(
          maxHeight: MediaQuery.of(context).size.height * 0.75,
        ),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const SizedBox(height: 10),
            Container(
              width: 40,
              height: 4,
              decoration: BoxDecoration(
                color: const Color(0xFFE0D6CC),
                borderRadius: BorderRadius.circular(2),
              ),
            ),
            Padding(
              padding: const EdgeInsets.fromLTRB(20, 14, 20, 6),
              child: Align(
                alignment: Alignment.centerLeft,
                child: Text(
                  widget.title,
                  style: const TextStyle(
                    fontSize: 16,
                    fontWeight: FontWeight.w600,
                    color: Color(0xFF5D4037),
                  ),
                ),
              ),
            ),
            Flexible(
              child: ListView(
                shrinkWrap: true,
                padding: const EdgeInsets.fromLTRB(12, 4, 12, 20),
                children: [
                  if (widget.showAll)
                    _row(
                      icon: 'education',
                      name: '全部',
                      count: widget.tree.totalCount,
                      depth: 0,
                      selected: _isCurrent(NoteScope.all, null),
                      onTap: () => Navigator.pop(context, NoteLocation.all),
                    ),
                  _row(
                    icon: 'income',
                    name: '未分类',
                    count: widget.tree.uncategorizedCount,
                    depth: 0,
                    selected: _isCurrent(NoteScope.uncategorized, null),
                    onTap: () => Navigator.pop(context, NoteLocation.uncategorized),
                  ),
                  if (widget.tree.folders.isNotEmpty)
                    const Padding(
                      padding: EdgeInsets.fromLTRB(8, 12, 8, 4),
                      child: Divider(height: 1, color: Color(0xFFF0E6D8)),
                    ),
                  ...widget.tree.folders.map((n) => _buildNode(n, 0)),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  /// 递归渲染目录节点
  Widget _buildNode(FolderNode node, int depth) {
    final hasChildren = node.children.isNotEmpty;
    final open = _expanded.contains(node.id);

    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        _row(
          icon: (open && hasChildren) ? 'folder-open' : 'folder',
          name: node.name,
          count: node.noteCount,
          depth: depth,
          selected: _isCurrent(NoteScope.folder, node.id),
          trailing: hasChildren
              ? GestureDetector(
                  behavior: HitTestBehavior.opaque,
                  onTap: () {
                    setState(() {
                      if (open) {
                        _expanded.remove(node.id);
                      } else {
                        _expanded.add(node.id);
                      }
                    });
                  },
                  child: Padding(
                    padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 8),
                    child: AnimatedRotation(
                      turns: open ? 0.25 : 0,
                      duration: const Duration(milliseconds: 150),
                      child: const Icon(
                        Icons.chevron_right,
                        size: 18,
                        color: Color(0xFFBCAAA4),
                      ),
                    ),
                  ),
                )
              : null,
          onTap: () => Navigator.pop(
            context,
            NoteLocation(
              scope: NoteScope.folder,
              folderId: node.id,
              folderName: node.name,
            ),
          ),
        ),
        if (open && hasChildren)
          ...node.children.map((c) => _buildNode(c, depth + 1)),
      ],
    );
  }

  Widget _row({
    required String icon,
    required String name,
    required int count,
    required int depth,
    required bool selected,
    required VoidCallback onTap,
    Widget? trailing,
  }) {
    return Padding(
      padding: EdgeInsets.only(left: depth * 18.0),
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(10),
        child: Container(
          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 10),
          decoration: BoxDecoration(
            color: selected ? const Color(0xFFFFF3E6) : null,
            borderRadius: BorderRadius.circular(10),
          ),
          child: Row(
            children: [
              CuteIcon(icon, size: 17),
              const SizedBox(width: 10),
              Expanded(
                child: Text(
                  name,
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                  style: TextStyle(
                    fontSize: 14.5,
                    fontWeight: selected ? FontWeight.w600 : FontWeight.normal,
                    color: selected ? const Color(0xFFC8956E) : const Color(0xFF5D4037),
                  ),
                ),
              ),
              Text(
                '$count',
                style: const TextStyle(fontSize: 12, color: Color(0xFFBCAAA4)),
              ),
              ?trailing,
            ],
          ),
        ),
      ),
    );
  }
}