// See https://aka.ms/new-console-template for more information

using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;

Console.WriteLine("Installer is suck");

if (args.Length == 0)
{
    Console.WriteLine("Usage: <inDir> <outDir>");
    return;
}

var dirIn = Path.GetFullPath(args[0]);
var dirOut = Path.GetFullPath(args[1]);

var files = Directory.GetFiles(dirIn);
foreach (var file in files)
{
    try
    {
        Console.WriteLine($"> {file}");

        var hl = HardLinkHelper.GetFileLinkCount(file);
        if (hl > 1)
        {
            Console.WriteLine(" SKIP");
            continue;
        }

        var info = new FileInfo(file);
        Console.WriteLine($" Len: {info.Length:N0}");
        Console.Write(" SHA256...");
        string hexHash;
        {
            using var inputStream = info.OpenRead();
            using var sha256 = SHA256.Create();
            var hash = sha256.ComputeHash(inputStream);
            hexHash = Convert.ToHexString(hash);
        }
        Console.WriteLine($" {hexHash}");

        var targetPath = Path.Combine(dirOut, $"{info.Length:0-000-000-000}_{hexHash}{info.Extension}");
        if (File.Exists(targetPath))
        {
            try
            {
                File.Delete(file);
            }
            catch (UnauthorizedAccessException)
            {
                Console.WriteLine($" Warn: Failure to delete {file}, moved to append ._del");
                File.Move(file, file + "._del");
            }
        }
        else
        {
            File.Move(file, targetPath);
        }

        HardLinkHelper.CreateHardLink(file, targetPath);
        Console.WriteLine($" Collapse to {targetPath} <");
    }
    catch (Exception e)
    {
        Console.WriteLine($"Error:{e.Message}");
    }
    Console.WriteLine();
}

public static class HardLinkHelper
{
    // P/Invoke 声明

    [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
    private static extern IntPtr FindFirstFileNameW(
        string lpFileName,
        uint dwFlags,
        ref uint lpdwBufferSize,
        StringBuilder lpLinkName
    );

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool FindNextFileNameW(
        IntPtr hFindStream,
        ref uint lpdwBufferSize,
        StringBuilder lpLinkName
    );

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool FindClose(IntPtr hFindStream);

    [DllImport("Kernel32.dll", CharSet = CharSet.Unicode)]
    private static extern bool CreateHardLink(
        string lpFileName,
        string lpExistingFileName,
        IntPtr lpSecurityAttributes
    );

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool GetFileInformationByHandle(
        SafeFileHandle hFile,
        out BY_HANDLE_FILE_INFORMATION lpFileInformation
    );

    [StructLayout(LayoutKind.Sequential)]
    private struct BY_HANDLE_FILE_INFORMATION
    {
        public uint FileAttributes;
        public uint FileCreationTimeLow;
        public uint FileCreationTimeHigh;
        public uint LastAccessTimeLow;
        public uint LastAccessTimeHigh;
        public uint LastWriteTimeLow;
        public uint LastWriteTimeHigh;
        public uint VolumeSerialNumber;
        public uint FileSizeHigh;
        public uint FileSizeLow;
        public uint NumberOfLinks;  // 硬链接数量
        public uint FileIndexHigh;
        public uint FileIndexLow;
    }

    [DllImport("kernel32.dll")]
    private static extern bool GetVolumePathName(string lpszFileName,
        [Out] StringBuilder lpszVolumePathName, uint cchBufferLength);

    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern SafeFileHandle CreateFile(
        string lpFileName,
        [MarshalAs(UnmanagedType.U4)] FileAccess dwDesiredAccess,
        [MarshalAs(UnmanagedType.U4)] FileShare dwShareMode,
        IntPtr lpSecurityAttributes,
        [MarshalAs(UnmanagedType.U4)] FileMode dwCreationDisposition,
        [MarshalAs(UnmanagedType.U4)] FileAttributes dwFlagsAndAttributes,
        IntPtr hTemplateFile);

    [DllImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool CloseHandle(SafeHandle hObject);

    [DllImport("shlwapi.dll", CharSet = CharSet.Auto)]
    private static extern bool PathAppend([In, Out] StringBuilder pszPath, string pszMore);

    public static bool CreateHardLink(string link, string to)
    {
        return CreateHardLink(link, to, nint.Zero);
    }

    public static int GetFileLinkCount(string filepath)
    {
        int result = 0;
        SafeFileHandle handle = CreateFile(filepath, FileAccess.Read, FileShare.Read, IntPtr.Zero, FileMode.Open, FileAttributes.Archive, IntPtr.Zero);
        BY_HANDLE_FILE_INFORMATION fileInfo = new BY_HANDLE_FILE_INFORMATION();
        if (GetFileInformationByHandle(handle, out fileInfo))
            result = (int)fileInfo.NumberOfLinks;
        CloseHandle(handle);
        return result;
    }

    //public static string[] GetFileSiblingHardLinks(string filepath)
    //{
    //    List<string> result = new List<string>();
    //    uint stringLength = 256;
    //    StringBuilder sb = new StringBuilder(1024);
    //    GetVolumePathName(filepath, sb, stringLength);
    //    string volume = sb.ToString();
    //    sb.Length = 0; stringLength = 1024;
    //    IntPtr findHandle = FindFirstFileNameW(filepath, 0, ref stringLength, sb);
    //    if (findHandle.ToInt64() != -1)
    //    {
    //        do
    //        {
    //            StringBuilder pathSb = new StringBuilder(volume, 1024);
    //            PathAppend(pathSb, sb.ToString());
    //            result.Add(pathSb.ToString());
    //            sb.Length = 0; stringLength = 1024;
    //        } while (FindNextFileNameW(findHandle, ref stringLength, sb));
    //        FindClose(findHandle);
    //        return result.ToArray();
    //    }
    //    return null;
    //}

    ///// <summary>
    ///// 获取指定文件的所有硬链接路径
    ///// </summary>
    ///// <param name="filePath">目标文件的路径</param>
    ///// <returns>文件的所有硬链接路径集合</returns>
    //public static IEnumerable<string> GetHardLinks(string filePath)
    //{
    //    var hardLinks = new List<string>();
    //    try
    //    {
    //        // 获取文件信息
    //        using (var fileStream = File.Open(filePath, FileMode.Open, FileAccess.Read))
    //        {
    //            BY_HANDLE_FILE_INFORMATION fileInfo;
    //            if (GetFileInformationByHandle(fileStream.SafeFileHandle, out fileInfo))
    //            {
    //                Console.WriteLine($"硬链接数量: {fileInfo.NumberOfLinks}");
    //                if (fileInfo.NumberOfLinks > 1)
    //                {
    //                    uint bufferSize = 1024;
    //                    StringBuilder linkName = new StringBuilder((int)bufferSize);
    //                    IntPtr handle = FindFirstFileNameW(filePath, 0, ref bufferSize, linkName);
    //                    if (handle != IntPtr.Zero)
    //                    {
    //                        do
    //                        {
    //                            hardLinks.Add(linkName.ToString());
    //                            bufferSize = 1024;
    //                            linkName.Clear();
    //                        } while (FindNextFileNameW(handle, ref bufferSize, linkName));
    //                        FindClose(handle);
    //                    }
    //                }
    //            }
    //            else
    //            {
    //                Console.WriteLine("无法获取文件信息.");
    //            }
    //        }
    //    }
    //    catch (Exception ex)
    //    {
    //        Console.WriteLine($"错误: {ex.Message}");
    //    }
    //    return hardLinks;
    //}
}