MainForm.cs

using System.Runtime.InteropServices;
using WindowsShortcutFactory;
using File = System.IO.File;

namespace TaskSplitter11
{
    public partial class MainForm : Form
    {
        public enum ShowWindowCommands
        {
            SW_HIDE = 0,
            SW_SHOWNORMAL = 1,
            SW_NORMAL = 1,
            SW_SHOWMINIMIZED = 2,
            SW_SHOWMAXIMIZED = 3,
            SW_MAXIMIZE = 3,
            SW_SHOWNOACTIVATE = 4,
            SW_SHOW = 5,
            SW_MINIMIZE = 6,
            SW_SHOWMINNOACTIVE = 7,
            SW_SHOWNA = 8,
            SW_RESTORE = 9,
            SW_SHOWDEFAULT = 10,
            SW_MAX = 10
        }

        [DllImport("shell32.dll", CharSet = CharSet.Auto)]
        private static extern IntPtr ShellExecute(
            IntPtr hwnd,
            [MarshalAs(UnmanagedType.LPWStr)] string lpszOp,
            [MarshalAs(UnmanagedType.LPWStr)] string lpszFile,
            [MarshalAs(UnmanagedType.LPWStr)] string lpszParams,
            [MarshalAs(UnmanagedType.LPWStr)] string lpszDir,
            ShowWindowCommands FsShowCmd
        );

        public MainForm()
        {
            InitializeComponent();
        }

        private void BtnCreate_Click(object sender, EventArgs e)
        {
            //Setup & config
            string? appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
            string? appPath = Path.GetDirectoryName(Application.ExecutablePath);
            string? shortcutsPath = Path.Join(appDataPath, "TaskSeparator11", "Shortcuts");
            Directory.CreateDirectory(shortcutsPath);

            //Ensure files are in thwe right place
            EnsureSplitterFilesAreAvailable(appPath, shortcutsPath);

            //Make a copy of the Splitter exe
            string splitterExe = Path.Join(appPath, "Splitter.exe");
            string splitterExeLocation = GetNewLinkName(shortcutsPath, "exe");
            File.Copy(splitterExe, splitterExeLocation);

            //Create a shortcut to the Splitter exe
            string linkLocation = GetNewLinkName(shortcutsPath, "lnk");

            //Create shortcut
            using var shortcut = new WindowsShortcut
            {
                Path = splitterExeLocation,
            };
            shortcut.Save(linkLocation);

            ShellExecute(IntPtr.Zero, "open", linkLocation, "--gui", "", ShowWindowCommands.SW_NORMAL);

            Application.Exit();
        }

        private static void EnsureSplitterFilesAreAvailable(string? appPath, string shortcutsPath)
        {
            if (File.Exists(Path.Join(shortcutsPath, "Splitter.dll")) || string.IsNullOrWhiteSpace(appPath)) return;

            var dir = new DirectoryInfo(appPath);
            var files = dir.GetFiles("Splitter*");

            files.Select(f => f.Name).ToList().ForEach(fileName =>
            {
                var source = Path.Join(appPath, fileName);
                var dest = Path.Join(shortcutsPath, fileName);
                File.Copy(source, dest, true);
            });
        }

        private static string GetNewLinkName(string path, string ext)
        {
            int count = 1;
            char c = ext == "exe" ? '_' : ' ';

            string shortcutLink;
            do
            {
                shortcutLink = Path.Join(path, $"{new string(c, count)}.{ext}");
                count++;
            } while (File.Exists(shortcutLink));

            return shortcutLink;
        }
    }
}