using Ookii.Dialogs;
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public class UnityOpenFolder
{
    public struct ExtensionFilter
    {
        public string Name;
        public string[] Extensions;

        public ExtensionFilter(string filterName, params string[] filterExtensions)
        {
            Name = filterName;
            Extensions = filterExtensions;
        }
    }

    public class WindowWrapper : IWin32Window
    {
        private IntPtr _hwnd;
        public WindowWrapper(IntPtr handle) { _hwnd = handle; }
        public IntPtr Handle { get { return _hwnd; } }
    }


    [DllImport("user32.dll")]
    private static extern IntPtr GetActiveWindow();

    public static string[] OpenFilePanel(string title, string directory, ExtensionFilter[] extensions, bool multiselect)
    {
        var fd = new VistaOpenFileDialog();
        fd.Title = title;
        if (extensions != null)
        {
            fd.Filter = GetFilterFromFileExtensionList(extensions);
            fd.FilterIndex = 1;
        }
        else
        {
            fd.Filter = string.Empty;
        }
        fd.Multiselect = multiselect;
        if (!string.IsNullOrEmpty(directory))
        {
            fd.FileName = GetDirectoryPath(directory);
        }
        var res = fd.ShowDialog(new WindowWrapper(GetActiveWindow()));
        var filenames = res == DialogResult.OK ? fd.FileNames : new string[0];
        fd.Dispose();
        return filenames;
    }


    private static string GetFilterFromFileExtensionList(ExtensionFilter[] extensions)
    {
        var filterString = "";
        foreach (var filter in extensions)
        {
            filterString += filter.Name + "(";

            foreach (var ext in filter.Extensions)
            {
                filterString += "*." + ext + ",";
            }

            filterString = filterString.Remove(filterString.Length - 1);
            filterString += ") |";

            foreach (var ext in filter.Extensions)
            {
                filterString += "*." + ext + "; ";
            }

            filterString += "|";
        }
        filterString = filterString.Remove(filterString.Length - 1);
        return filterString;
    }

    private static string GetDirectoryPath(string directory)
    {
        var directoryPath = Path.GetFullPath(directory);
        if (!directoryPath.EndsWith("\\"))
        {
            directoryPath += "\\";
        }
        if (Path.GetPathRoot(directoryPath) == directoryPath)
        {
            return directory;
        }
        return Path.GetDirectoryName(directoryPath) + Path.DirectorySeparatorChar;
    }
}