/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using System;

namespace Leap.Unity
{

    /// <summary>
    /// An object you can use to represent a single Unity layer 
    /// as a dropdown in the inspector.  Can be converted back and 
    /// forth between the integer representation Unity usually
    /// uses in its own methods.
    /// </summary>
    [Serializable]
    public struct SingleLayer : IEquatable<SingleLayer>
    {
        public int layerIndex;

        public int layerMask
        {
            get
            {
                return 1 << layerIndex;
            }
            set
            {
                if (value == 0)
                {
                    throw new ArgumentException("Single layer can only represent exactly one layer.  The provided mask represents no layers (mask was zero).");
                }

                int newIndex = 0;
                while ((value & 1) == 0)
                {
                    value = value >> 1;
                    newIndex++;
                }

                if (value != 1)
                {
                    throw new ArgumentException("Single layer can only represent exactly one layer.  The provided mask represents more than one layer.");
                }

                layerIndex = newIndex;
            }
        }

        public static implicit operator int(SingleLayer singleLayer)
        {
            return singleLayer.layerIndex;
        }

        public static implicit operator SingleLayer(int layerIndex)
        {
            SingleLayer singleLayer = new SingleLayer();
            singleLayer.layerIndex = layerIndex;
            return singleLayer;
        }

        public bool Equals(SingleLayer other)
        {
            return this.layerIndex == other.layerIndex;
        }
    }
}