#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 signed integer values.
/// </summary>
public struct Short4 : IPackedVector<ulong>, IEquatable<Short4>
{
	#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 Short4 class.
	/// </summary>
	/// <param name="vector">
	/// A vector containing the initial values for the components of the Short4 structure.
	/// </param>
	public Short4(Vector4 vector)
	{
			packedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
		}

	/// <summary>
	/// Initializes a new instance of the Short4 class.
	/// </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 w component.</param>
	public Short4(float x, float y, float z, float w)
	{
			packedValue = Pack(x, y, z, 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(
				(short) (packedValue & 0xFFFF),
				(short) ((packedValue >> 16) & 0xFFFF),
				(short) ((packedValue >> 32) & 0xFFFF),
				(short) (packedValue >> 48)
			);
		}

	#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>
	/// 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 !=(Short4 a, Short4 b)
	{
			return a.PackedValue != b.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 ==(Short4 a, Short4 b)
	{
			return a.PackedValue == b.PackedValue;
		}

	/// <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 Short4) && Equals((Short4) 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(Short4 other)
	{
			return this == other;
		}

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

	#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>
	static ulong Pack(float x, float y, float z, float w)
	{
			return (ulong) (
				((long) System.Math.Round(Math.Clamp(x, -32768, 32767)) & 0xFFFF) |
				(((long) System.Math.Round(Math.Clamp(y, -32768, 32767)) << 16) & 0xFFFF0000) |
				(((long) System.Math.Round(Math.Clamp(z, -32768, 32767)) << 32) & 0xFFFF00000000) |
				((long) System.Math.Round(Math.Clamp(w, -32768, 32767)) << 48)
			);
		}

	#endregion
}