TileviewModel2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Reversi.Cells;
using Reversi.Domain;
using System.Windows.Input;
using System.Windows.Media;
using System.ComponentModel;

namespace ReversiGUI.ViewModels
{
    class TileViewModel
    {
        private readonly ISquare square;
        private readonly ICommand placeStoneCommand;
        private readonly Game game;
        private readonly ICell<String> colorCell;

        public TileViewModel(ISquare square, Game game)
        {
            this.square = square;
            this.game = game;
            placeStoneCommand = new PlaceStoneCommando(this);

            colorCell = Cell.Derived(square.Owner, square.IsValidMove, DeriveColor);
        }

        public ICell<String> ColorCell
        {
            get { return colorCell; }
        }

        public ICell<bool> IsValidMove
        {
            get
            {
                return square.IsValidMove;
            }
        }

        private String DeriveColor(Player owner, bool isValidMove)
        {
            String temp = "";
            if ((square.Owner.Value) == null)
            {
                if (square.IsValidMove.Value)
                {
                    temp = "ValidMove";
                }
                else
                {
                    temp = "NoTile";
                }
            }
            else
            {
                if ((square.Owner.Value) == Player.ONE)
                {
                    temp = "PlayerOne";
                }
                else
                {
                    temp = "PlayerTwo";
                }
            }
            return temp;
        }

        public void PlaceStone()
        {
            if (square.IsValidMove.Value)
            {
                square.PlaceStone();
            }
        }

        public ICommand PlaceStoneCommand
        {
            get
            {
                return placeStoneCommand;
            }
        }

        private class PlaceStoneCommando : ICommand
        {
            private readonly TileViewModel model;

            public PlaceStoneCommando(TileViewModel model)
            {
                this.model = model;
                model.IsValidMove.PropertyChanged += IsValidMove_PropertyChanged;
            }

            void IsValidMove_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
            {
                if (CanExecuteChanged != null)
                    CanExecuteChanged(this, new EventArgs());
            }

            public bool CanExecute(object parameter)
            {
                return model.IsValidMove.Value;
                //return true;
            }

            public event EventHandler CanExecuteChanged;

            public void Execute(object parameter)
            {
                model.PlaceStone();
            }
        }
    }
}