using System;
using Cairo;
using Gtk;


public class V4 : Window
{
    DrawingArea da;
    private PointD start, end;
    private bool click;
    private int breyta;
    public V4():base("mikki reddar þessu")
    {
        da = new DrawingArea();
        da.AddEvents((int)Gdk.EventMask.AllEventsMask);


        da.ButtonPressEvent += OnMousePress;
        da.ButtonReleaseEvent += OnMouseRelease;

        KeyPressEvent += KeyPressHandler;
        da.ExposeEvent += ODAE;

        SetDefaultSize(300,200);
        SetPosition(WindowPosition.Center);

        DeleteEvent += delegate { Application.Quit(); };


        Add(da);
        ShowAll();
    }


    void ODAE(object source, ExposeEventArgs args)
    {
        using (Cairo.Context ctx = Gdk.CairoHelper.Create(da.GdkWindow))
        {
            if(breyta == 1)
            {
                DL(ctx, start,end);
            }
            if(breyta == 2)
            {
                DR(ctx, start,end);
            }
            if(breyta == 3)
            {
                DE(ctx,start,end);
            }
        }
    }
    void KeyPressHandler(object sender, KeyPressEventArgs args)
    {
            switch (args.Event.Key)
            {
                case Gdk.Key.l:
                    breyta = 1;
                    break;
                case Gdk.Key.r:
                    breyta = 2;
                    break;
                case Gdk.Key.e:
                    breyta = 3;
                    break;
            }
    }
    public static void DL(Context ctx, PointD start, PointD end)
    {
        ctx.Save();
        ctx.MoveTo(start);
        ctx.LineTo(end);
        ctx.Restore();
        ctx.Stroke();

    }
    public static void DR(Context ctx, PointD start, PointD end)
    {
        double starty = start.Y;
        double startx = start.X;

        double swapx = Math.Abs(end.X - start.X);
        double swapy = Math.Abs(end.Y - start.Y);
        ctx.Save();
        if(( end.X - start.X) < 0 )
        {
            if((end.Y - start.Y) > 0)
            {
                ctx.Rectangle(startx - swapx,starty,swapx,swapy);
                ctx.Stroke();
                ctx.Save();
            }
            else
            {
                ctx.Rectangle(startx - swapx,starty - swapy,swapx,swapy);
                ctx.Stroke();
                ctx.Save();
            }
        }
        else
        {
            if((end.Y-start.Y) > 0)
            {
                ctx.Rectangle(startx,starty,swapx,swapy);
                ctx.Stroke();
                ctx.Save();
            }
            else
            {
                ctx.Rectangle(startx,starty-swapy,swapx,swapy);
                ctx.Stroke();
                ctx.Save();
            }
        }


    }
    public static void DE(Context ctx, PointD start, PointD end)
    {
        double width = Math.Abs(start.X - end.X);
        double height = Math.Abs(start.Y - end.Y);
        double xcenter = start.X + (end.X - start.X) / 2.0;
        double ycenter = start.Y + (end.Y - start.Y) / 2.0;

        ctx.Save();
        ctx.Translate(xcenter, ycenter);
        ctx.Scale(width/2.0, height/2.0);
        ctx.Arc(0.0, 0.0, 1.0, 0.0, 2*Math.PI);
        ctx.Restore();
        ctx.Stroke();

    }
    void OnMousePress(object source, ButtonPressEventArgs args)
    {
        click = true;
        start = new PointD(args.Event.X, args.Event.Y);
        da.GrabFocus();
    }
    void OnMouseRelease(object source, ButtonReleaseEventArgs args)
    {
        click = false;
        end = new PointD(args.Event.X, args.Event.Y);
        da.QueueDraw();
    }
    public static void Main()
    {
        Application.Init();
        new V4();
        Application.Run();
    }

}