using System;
using System.Threading;

// Wrapper class for the console allowing concurrent read and write operations
public class Terminal
{
	private Object TerminalLock = new Object ();
	private Object ReadLineLock = new Object ();
	private AutoResetEvent ResetEvent = new AutoResetEvent (false);
	private String InputBuffer = "";
	private bool AcceptInput = false;
	private int OutLinePos;
	private Thread catchInputThread;

	public Terminal ()
	{
		OutLinePos = Console.CursorTop;
		catchInputThread = new Thread (new ThreadStart (this.CatchInput));
		catchInputThread.Start ();
	}

	private void CatchInput ()
	{
		while (true) {
			ConsoleKeyInfo key = Console.ReadKey (false);
			lock (TerminalLock) {
				if (!AcceptInput) {
					Console.CursorLeft--;
					Console.Write (" ");
					Console.CursorLeft--;
					continue;
				}
				if (key.Key == ConsoleKey.Backspace) {
					if (InputBuffer.Length == 0)
						continue;
					InputBuffer = InputBuffer.Substring (0, InputBuffer.Length - 1);
					ClearInputLine ();
					Console.Write (InputBuffer);
				} else if (key.Key == ConsoleKey.Enter) {
					AcceptInput = false;
					ResetEvent.Set ();
					OutLinePos = Console.CursorTop;
				} else {
					InputBuffer += key.KeyChar;
					ClearInputLine ();
					Console.Write (InputBuffer);
				}
			}
		}
	}

	public void PrintLine (String s)
	{
		lock (TerminalLock) {
			ClearInputLine ();
			Console.WriteLine (s);
			OutLinePos = Console.CursorTop;
			Console.Write (InputBuffer);
		}
	}

	public String ReadLine ()
	{
		lock (ReadLineLock) {
			try {
				String result;
				AcceptInput = true;
				ResetEvent.WaitOne ();
				result = InputBuffer;
				InputBuffer = "";
				return result;
			} catch (ThreadAbortException e) {
				lock (TerminalLock) {
					AcceptInput = false;
					InputBuffer = "";
					ClearInputLine ();
				}
				throw e;
			}
		}
	}

	public void ClearInputLine ()
	{
		lock (TerminalLock) {
			int top = Console.CursorTop;
			int left = Console.CursorLeft;
			Console.SetCursorPosition (0, OutLinePos);
			while (left != Console.CursorLeft || top != Console.CursorTop) {
				Console.Write (" ");
			}
			Console.SetCursorPosition (0, OutLinePos);
		}
	}

	public void Close ()
	{
		catchInputThread.Abort();
	}
}