/* 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.
 */

using System.Numerics;

namespace Nerfed.Runtime.Graphics.PackedVector;

/// <summary>
/// Packed vector type containing unsigned normalized values ranging from 0 to 1.
/// The x and z components use 5 bits, and the y component uses 6 bits.
/// </summary>
public struct Alpha8 : IPackedVector<byte>, IEquatable<Alpha8>, IPackedVector
{
	#region Public Properties

	/// <summary>
	/// Gets and sets the packed value.
	/// </summary>
	public byte PackedValue
	{
		get
		{
			return packedValue;
		}
		set
		{
			packedValue = value;
		}
	}

	#endregion

	#region Private Variables

	private byte packedValue;

	#endregion

	#region Public Constructor

	/// <summary>
	/// Creates a new instance of Alpha8.
	/// </summary>
	/// <param name="alpha">The alpha component</param>
	public Alpha8(float alpha)
	{
		packedValue = Pack(alpha);
	}

	#endregion

	#region Public Methods

	/// <summary>
	/// Gets the packed vector in float format.
	/// </summary>
	/// <returns>The packed vector in Vector3 format</returns>
	public float ToAlpha()
	{
		return (float) (packedValue / 255.0f);
	}

	#endregion

	#region IPackedVector Methods

	/// <summary>
	/// Sets the packed vector from a Vector4.
	/// </summary>
	/// <param name="vector">Vector containing the components.</param>
	void IPackedVector.PackFromVector4(Vector4 vector)
	{
		packedValue = Pack(vector.W);
	}

	/// <summary>
	/// Gets the packed vector in Vector4 format.
	/// </summary>
	/// <returns>The packed vector in Vector4 format</returns>
	Vector4 IPackedVector.ToVector4()
	{
		return new Vector4(
			0.0f,
			0.0f,
			0.0f,
			(float) (packedValue / 255.0f)
		);
	}

	#endregion

	#region Public Static Operators and Override Methods

	/// <summary>
	/// Compares an object with the packed vector.
	/// </summary>
	/// <param name="obj">The object to compare.</param>
	/// <returns>True if the object is equal to the packed vector.</returns>
	public override bool Equals(object obj)
	{
		return (obj is Alpha8) && Equals((Alpha8) obj);
	}

	/// <summary>
	/// Compares another Bgra5551 packed vector with the packed vector.
	/// </summary>
	/// <param name="other">The Bgra5551 packed vector to compare.</param>
	/// <returns>True if the packed vectors are equal.</returns>
	public bool Equals(Alpha8 other)
	{
		return packedValue == other.packedValue;
	}

	/// <summary>
	/// Gets a string representation of the packed vector.
	/// </summary>
	/// <returns>A string representation of the packed vector.</returns>
	public override string ToString()
	{
		return packedValue.ToString("X");
	}

	/// <summary>
	/// Gets a hash code of the packed vector.
	/// </summary>
	/// <returns>The hash code for the packed vector.</returns>
	public override int GetHashCode()
	{
		return packedValue.GetHashCode();
	}

	public static bool operator ==(Alpha8 lhs, Alpha8 rhs)
	{
		return lhs.packedValue == rhs.packedValue;
	}

	public static bool operator !=(Alpha8 lhs, Alpha8 rhs)
	{
		return lhs.packedValue != rhs.packedValue;
	}

	#endregion

	#region Private Static Pack Method

	private static byte Pack(float alpha)
	{
		return (byte) System.Math.Round(Math.Clamp(alpha, 0, 1) * 255.0f);
	}

	#endregion
}