#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 System.Numerics;
#endregion

namespace Nerfed.Runtime.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
}