using System;
using System.IO;
using System.Linq;
using System.Text;

class Program
{
    static string treeFilePath;

    static void Main()
    {
        // 获取 exe 所在目录（去掉末尾的斜杠）
        string rootPath = AppDomain.CurrentDomain.BaseDirectory
                          .TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);

        // tree.txt 的完整路径（用于排除自身）
        treeFilePath = Path.Combine(rootPath, "tree.txt");

        // 使用 UTF-8 带 BOM 的编码覆盖写入
        using (var writer = new StreamWriter(treeFilePath, false, Encoding.UTF8))
        {
            WriteTree(rootPath, writer);
        }

        Console.WriteLine("\n树形结构已保存到: " + treeFilePath);
        Console.WriteLine("按任意键退出...");
        Console.ReadKey();
    }

    // 写入整棵目录树
    static void WriteTree(string rootPath, StreamWriter writer)
    {
        // 输出根节点（完整路径）
        string rootLine = rootPath;
        writer.WriteLine(rootLine);
        Console.WriteLine(rootLine);

        DirectoryInfo rootDir;
        try
        {
            rootDir = new DirectoryInfo(rootPath);
            // 获取根目录下的所有文件/文件夹（带异常保护）
            FileSystemInfo[] entries = GetFilteredSortedEntries(rootDir);
            for (int i = 0; i < entries.Length; i++)
            {
                bool isLast = (i == entries.Length - 1);
                WriteEntry(entries[i], "", isLast, writer);
            }
        }
        catch (UnauthorizedAccessException)
        {
            // 根目录通常不会无权限，这里保底不输出任何内容
        }
    }

    // 递归写入每一个条目（文件或文件夹）
    static void WriteEntry(FileSystemInfo entry, string indent, bool isLast, StreamWriter writer)
    {
        // 分支符号：最后一个用 └──，否则用 ├──
        string branch = isLast ? "└──" : "├──";
        string line = indent + branch + entry.Name;

        writer.WriteLine(line);
        Console.WriteLine(line);

        // 如果是文件夹，继续递归其子项
        if (entry is DirectoryInfo dir)
        {
            // 子项缩进：若当前是最后一项，后继用空格；否则保留竖线
            string childIndent = indent + (isLast ? "    " : "│   ");

            try
            {
                FileSystemInfo[] children = GetFilteredSortedEntries(dir);
                for (int i = 0; i < children.Length; i++)
                {
                    bool childIsLast = (i == children.Length - 1);
                    WriteEntry(children[i], childIndent, childIsLast, writer);
                }
            }
            catch (UnauthorizedAccessException)
            {
                // 无权限访问子文件夹 → 仅显示目录名，不再继续
            }
        }
    }

    // 获取指定目录下过滤并排序后的文件系统条目
    static FileSystemInfo[] GetFilteredSortedEntries(DirectoryInfo dir)
    {
        return dir.GetFileSystemInfos()
                  .Where(e =>
                  {
                      // 排除隐藏和系统属性
                      if ((e.Attributes & FileAttributes.Hidden) == FileAttributes.Hidden ||
                          (e.Attributes & FileAttributes.System) == FileAttributes.System)
                          return false;

                      // 排除 tree.txt 自身
                      if (string.Equals(e.FullName, treeFilePath, StringComparison.OrdinalIgnoreCase))
                          return false;

                      return true;
                  })
                  .OrderBy(e => e.Name, StringComparer.OrdinalIgnoreCase)  // 字母升序，不区分大小写
                  .ToArray();
    }
}