#nullable enable
using System.Diagnostics.Contracts;
using System.Numerics;

namespace Terminal.Gui;

public readonly partial record struct Color {

	/// <inheritdoc />
	/// <returns>
	///   A <see cref="Color" /> <see langword="struct" /> with all values set to <see cref="byte.MaxValue" />, meaning white.
	/// </returns>
	public static Color MaxValue => new Color (uint.MaxValue);

	/// <inheritdoc />
	/// <returns>A <see cref="Color" /> <see langword="struct" /> with all values set to zero.</returns>
	/// <remarks>
	///   Though this returns a <see cref="Color" /> with <see cref="A" />, <see cref="R" />, <see cref="G" />, and <see cref="B" /> all set to
	///   zero, Terminal.Gui will treat it as black, because the alpha channel is not supported.
	/// </remarks>
	public static Color MinValue => new Color (uint.MinValue);

	/// <inheritdoc />
	[Pure]
	public override int GetHashCode () => Rgba.GetHashCode ();

	/// <summary>
	///   Implicit conversion from <see cref="Color" /> to <see cref="Vector3" /> via <see cref="Vector3(float,float,float)" /> where (
	///   <see cref="Vector3.X" />, <see cref="Vector3.Y" />, <see cref="Vector3.Z" />) is (R,G,B).
	/// </summary>
	/// <remarks>
	///   This cast is narrowing and drops the alpha channel.
	///   <para />
	///   Use <see cref="implicit operator Vector4(Color)" /> to maintain full value.
	/// </remarks>
	[Pure]
	public static explicit operator Vector3 (Color color) => new Vector3 (color.R, color.G, color.B);
	/// <summary>
	///   Implicit conversion from <see langword="int" /> to <see cref="Color" />, via the <see cref="Color(int)" /> costructor.
	/// </summary>
	[Pure]
	public static implicit operator Color (int rgba) => new Color (rgba);

	/// <summary>
	///   Implicit conversion from <see cref="Color" /> to <see langword="int" /> by returning the value of the <see cref="Rgba" /> field.
	/// </summary>
	[Pure]
	public static implicit operator int (Color color) => color.Rgba;

	/// <summary>
	///   Implicit conversion from <see langword="uint" /> to <see cref="Color" />, via the <see cref="Color(uint)" /> costructor.
	/// </summary>
	[Pure]
	public static implicit operator Color (uint u) => new Color (u);

	/// <summary>
	///   Implicit conversion from <see cref="Color" /> to <see langword="uint" /> by returning the value of the <see cref="Argb" /> field.
	/// </summary>
	[Pure]
	public static implicit operator uint (Color color) => color.Argb;

	/// <summary>
	///   Implicit conversion from <see cref="GetClosestNamedColor" /> to <see cref="Color" /> via lookup from
	///   <see cref="ColorExtensions.ColorNameToColorMap" />.
	/// </summary>
	[Pure]
	public static implicit operator Color (ColorName colorName) => ColorExtensions.ColorNameToColorMap [colorName];

	/// <summary>
	///   Implicit conversion from <see cref="Vector4" /> to <see cref="Color" />, where (<see cref="Vector4.X" />, <see cref="Vector4.Y" />,
	///   <see cref="Vector4.Z" />, <see cref="Vector4.W" />) is (<see cref="A" />,<see cref="R" />,<see cref="G" />,<see cref="B" />), via
	///   <see cref="Color(int,int,int,int)" />.
	/// </summary>
	[Pure]
	public static implicit operator Color (Vector4 v) => new Color ((byte)v.X, (byte)v.Y, (byte)v.Z, (byte)v.W);

	/// <summary>
	///   Implicit conversion to <see cref="Vector3" />, where <see cref="Vector3.X" /> = <see cref="R" />, <see cref="Vector3.Y" /> =
	///   <see cref="G" />, and <see cref="Vector3.Z" /> = <see cref="B" />.
	/// </summary>
	[Pure]
	public static implicit operator Vector4 (Color color) => new Vector4 (color.R, color.G, color.B, color.A);

	/// <summary>
	///   Implicit conversion from <see cref="Vector3" />, where <see cref="Vector3.X" /> = <see cref="R" />, <see cref="Vector3.Y" /> =
	///   <see cref="G" />, and <see cref="Vector3.Z" /> = <see cref="B" />.
	/// </summary>
	[Pure]
	public static implicit operator Color (Vector3 v) => new Color ((byte)v.X, (byte)v.Y, (byte)v.Z);
}