using System;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Linq.Expressions;
 
namespace Reactive
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
 
            //Func<MouseEventArgs, int> slowOperation = args =>
            //{
            //    System.Threading.Thread.Sleep(3000);
            //    if(args.Button == MouseButtons.Middle)
            //        throw new Exception("MIDDLE BUTTON NOT ALLOWED!!!");
            //    return args.X;
            //};
 
            //IObservable<string> messages = from md in button1.GetMouseDowns()                                           
            //                               from x in slowOperation.AsAsyncObservable(md)
            //                               where md.Button == MouseButtons.Right
            //                               select "Mouse down: " + x + "\n";
 
            IObservable<MouseEventArgs> mouseEvents = button1.GetMouseDowns();
 
            IObservable<string> messages = from md in mouseEvents
                                           select "Mouse down at: " + md.X + "\n";
 
            messages.Subscribe(new TextBoxUpdater(textBox1));
        }
 
        public class TextBoxUpdater : IObserver<string>
        {
            private readonly TextBox _textBox;
 
            public TextBoxUpdater(TextBox textBox)
            {
                _textBox = textBox;
            }
 
            private void AppendText(string text)
            {
                Action textboxUpdater = () => _textBox.AppendText(text);
                _textBox.BeginInvoke(textboxUpdater);
            }
 
            public void OnNext(string s)
            {
                AppendText(s);
            }
 
            public void OnDone()
            {
                AppendText("Done\n");
            }
 
            public void OnError(Exception e)
            {
                AppendText("Error: " + e.Message);
            }
        }
 
    }
}