#region License

/* MoonWorks - Game Development Framework
 * Copyright 2021 Evan Hemsley
 */

/* Derived from code by Ethan Lee (Copyright 2009-2021).
 * Released under the Microsoft Public License.
 * See fna.LICENSE for details.

 * Derived from code by the Mono.Xna Team (Copyright 2006).
 * Released under the MIT License. See monoxna.LICENSE for details.
 */

#endregion

#region Using Statements
using System;
using MoonWorks.Math.Float;
#endregion

namespace MoonWorks.Graphics.PackedVector
{
	/// <summary>
	/// Packed vector type containing four 16-bit floating-point values.
	/// </summary>
	public struct HalfVector4 : IPackedVector<ulong>, IPackedVector, IEquatable<HalfVector4>
	{
		#region Public Properties

		/// <summary>
		/// Directly gets or sets the packed representation of the value.
		/// </summary>
		/// <value>The packed representation of the value.</value>
		public ulong PackedValue
		{
			get
			{
				return packedValue;
			}
			set
			{
				packedValue = value;
			}
		}

		#endregion

		#region Private Variables

		private ulong packedValue;

		#endregion

		#region Public Constructors

		/// <summary>
		/// Initializes a new instance of the HalfVector4 structure.
		/// </summary>
		/// <param name="x">Initial value for the x component.</param>
		/// <param name="y">Initial value for the y component.</param>
		/// <param name="z">Initial value for the z component.</param>
		/// <param name="w">Initial value for the q component.</param>
		public HalfVector4(float x, float y, float z, float w)
		{
			packedValue = Pack(x, y, z, w);
		}

		/// <summary>
		/// Initializes a new instance of the HalfVector4 structure.
		/// </summary>
		/// <param name="vector">
		/// A vector containing the initial values for the components of the HalfVector4
		/// structure.
		/// </param>
		public HalfVector4(Vector4 vector)
		{
			packedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
		}

		#endregion

		#region Public Methods

		/// <summary>
		/// Expands the packed representation into a Vector4.
		/// </summary>
		/// <returns>The expanded vector.</returns>
		public Vector4 ToVector4()
		{
			return new Vector4(
				HalfTypeHelper.Convert((ushort) packedValue),
				HalfTypeHelper.Convert((ushort) (packedValue >> 0x10)),
				HalfTypeHelper.Convert((ushort) (packedValue >> 0x20)),
				HalfTypeHelper.Convert((ushort) (packedValue >> 0x30))
			);
		}

		#endregion

		#region IPackedVector Methods

		/// <summary>
		/// Sets the packed representation from a Vector4.
		/// </summary>
		/// <param name="vector">The vector to create the packed representation from.</param>
		void IPackedVector.PackFromVector4(Vector4 vector)
		{
			packedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
		}

		#endregion

		#region Public Static Operators and Override Methods

		/// <summary>
		/// Returns a string representation of the current instance.
		/// </summary>
		/// <returns>String that represents the object.</returns>
		public override string ToString()
		{
			return packedValue.ToString("X");
		}

		/// <summary>
		/// Gets the hash code for the current instance.
		/// </summary>
		/// <returns>Hash code for the instance.</returns>
		public override int GetHashCode()
		{
			return packedValue.GetHashCode();
		}

		/// <summary>
		/// Returns a value that indicates whether the current instance is equal to a
		/// specified object.
		/// </summary>
		/// <param name="obj">The object with which to make the comparison.</param>
		/// <returns>
		/// True if the current instance is equal to the specified object; false otherwise.
		/// </returns>
		public override bool Equals(object obj)
		{
			return ((obj is HalfVector4) && Equals((HalfVector4) obj));
		}

		/// <summary>
		/// Returns a value that indicates whether the current instance is equal to a
		/// specified object.
		/// </summary>
		/// <param name="other">The object with which to make the comparison.</param>
		/// <returns>
		/// True if the current instance is equal to the specified object; false otherwise.
		/// </returns>
		public bool Equals(HalfVector4 other)
		{
			return packedValue.Equals(other.packedValue);
		}

		/// <summary>
		/// Compares the current instance of a class to another instance to determine
		/// whether they are the same.
		/// </summary>
		/// <param name="a">The object to the left of the equality operator.</param>
		/// <param name="b">The object to the right of the equality operator.</param>
		/// <returns>True if the objects are the same; false otherwise.</returns>
		public static bool operator ==(HalfVector4 a, HalfVector4 b)
		{
			return a.Equals(b);
		}

		/// <summary>
		/// Compares the current instance of a class to another instance to determine
		/// whether they are different.
		/// </summary>
		/// <param name="a">The object to the left of the equality operator.</param>
		/// <param name="b">The object to the right of the equality operator.</param>
		/// <returns>True if the objects are different; false otherwise.</returns>
		public static bool operator !=(HalfVector4 a, HalfVector4 b)
		{
			return !a.Equals(b);
		}

		#endregion

		#region Private Static Pack Method

		/// <summary>
		/// Packs a vector into a ulong.
		/// </summary>
		/// <param name="vector">The vector containing the values to pack.</param>
		/// <returns>The ulong containing the packed values.</returns>
		private static ulong Pack(float x, float y, float z, float w)
		{
			return (ulong) (
				((ulong) HalfTypeHelper.Convert(x)) |
				(((ulong) HalfTypeHelper.Convert(y) << 0x10)) |
				(((ulong) HalfTypeHelper.Convert(z) << 0x20)) |
				(((ulong) HalfTypeHelper.Convert(w) << 0x30))
			);
		}

		#endregion
	}
}
