FileSelector.cs

using System.Runtime.InteropServices;

namespace VaniFine
{
    public class FileSelector
    {
        [DllImport("comdlg32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern bool GetOpenFileName(ref OpenFileName ofn);
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern int MessageBox(IntPtr hWnd, String text, String caption, uint type);
        public static string ShowDialog()
        {
            if (!OperatingSystem.IsWindows())
            {
                Console.WriteLine("File dialog is only supported on Windows platforms. You can set your file path manually by using arguments.");
                Environment.Exit(-1);
            }
            var ofn = new OpenFileName();
            ofn.lStructSize = Marshal.SizeOf(ofn);
            ofn.lpstrFilter = "ZIP Archive\0*.zip\0All Files (*.*)\0*.*\0";
            ofn.lpstrFile = new string(new char[256]);
            ofn.nMaxFile = ofn.lpstrFile.Length;
            ofn.lpstrFileTitle = new string(new char[64]);
            ofn.nMaxFileTitle = ofn.lpstrFileTitle.Length;
            ofn.lpstrTitle = "Select Resource Pack";
            if (GetOpenFileName(ref ofn))
                return ofn.lpstrFile;
            return string.Empty;
        }
    }
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct OpenFileName
    {
        public int lStructSize;
        public IntPtr hwndOwner;
        public IntPtr hInstance;
        public string lpstrFilter;
        public string lpstrCustomFilter;
        public int nMaxCustFilter;
        public int nFilterIndex;
        public string lpstrFile;
        public int nMaxFile;
        public string lpstrFileTitle;
        public int nMaxFileTitle;
        public string lpstrInitialDir;
        public string lpstrTitle;
        public int Flags;
        public short nFileOffset;
        public short nFileExtension;
        public string lpstrDefExt;
        public IntPtr lCustData;
        public IntPtr lpfnHook;
        public string lpTemplateName;
        public IntPtr pvReserved;
        public int dwReserved;
        public int flagsEx;
    }
}