using System;
using Gtk;

class NMenuItem : MenuItem
{
  public name : string;
  
  public this(l : string) 
  {
    base(l);
    name = l;    
  }

  public this(l : string, e : object * EventArgs -> void) 
  {
    base(l);
    name = l;    
    this.Activated += e;
  }


        // this property allows us to set submenus of this menu item
  public SubmenuList : list [NMenuItem]
  { 
    set
    { 
      def sub = Menu();
                        foreach (submenu in value) sub.Append (submenu);
      this.Submenu = sub;
    }
  }
}


class MainWindow : Window
{
        /// text input area of our window
  input : TextView;

  public this()
  {
                // set caption of window
    base ("Very Simple Editor");
                // resize windows to some reasonable shape
    SetSizeRequest (300,200);

    def scroll = ScrolledWindow ();    
    input = TextView ();
    scroll.Add (input);

    def menu = MenuBar ();
    def mi = NMenuItem ("File");
    mi.SubmenuList = 
    [
      NMenuItem ("Open", OnMenuFile),
      NMenuItem ("Save as...", OnMenuFile)
    ];
    menu.Append(mi);    
    
    def vbox = VBox ();
    vbox.PackStart (menu, false, false, 0u);
          vbox.PackStart (scroll, true, true, 0u);

    // place vertical box inside our main window
    Add (vbox);
  }

        // handler of opening and saving files
  OnMenuFile (i : object, _ : EventArgs) : void
  {
    def mi = i :> NMenuItem;
    def fs = FileSelection (mi.name);
    
    when (fs.Run () == ResponseType.Ok :> int) match (mi.name)
    {
      | "Open" =>
                                def stream = IO.StreamReader (fs.Filename);
        input.Buffer.Text = stream.ReadToEnd();

      | "Save as..." =>
        def s = IO.StreamWriter(fs.Filename);
        s.Write(input.Buffer.Text);
        s.Close();
      | _ => ();
    };
    fs.Hide();
  }
}

module SimpleEditor
{ 
  Main() : void
  {
    Application.Init();
    def win = MainWindow();

                // exit application when editor window is deleted
                win.DeleteEvent += fun (_) { Application.Quit () };

                win.ShowAll ();
    Application.Run();
  }
}