using System;
using System.Collections.Generic;

using Microsoft.Xna.Framework;

namespace Nuclex
{
    internal class DrawOrderComparer : IComparer<IDrawable>
    {
        // Fields
        public static readonly DrawOrderComparer Default = new DrawOrderComparer();

        // Methods
        public int Compare(IDrawable x, IDrawable y)
        {
            if ((x == null) && (y == null))
            {
                return 0;
            }
            if (x != null)
            {
                if (y == null)
                {
                    return -1;
                }
                if (x.Equals(y))
                {
                    return 0;
                }
                if (x.DrawOrder < y.DrawOrder)
                {
                    return -1;
                }
            }
            return 1;
        }
    }
} // namespace Nuclex