using System;
using System.Runtime.InteropServices;
using Vanara.Extensions;

namespace Vanara.PInvoke
{
	/// <summary>The alpha intensity value for the palette entry.</summary>
	[PInvokeData("wingdi.h")]
	[Flags]
	public enum PC : byte
	{
		/// <summary>
		/// Specifies that the low-order word of the logical palette entry designates a hardware palette index. This flag allows the
		/// application to show the contents of the display device palette.
		/// </summary>
		PC_EXPLICIT = 0x2,

		/// <summary>
		/// Specifies that the color be placed in an unused entry in the system palette instead of being matched to an existing color in
		/// the system palette. If there are no unused entries in the system palette, the color is matched normally. Once this color is
		/// in the system palette, colors in other logical palettes can be matched to this color.
		/// </summary>
		PC_NOCOLLAPSE = 0x4,

		/// <summary>
		/// Specifies that the logical palette entry be used for palette animation. This flag prevents other windows from matching colors
		/// to the palette entry since the color frequently changes. If an unused system-palette entry is available, the color is placed
		/// in that entry. Otherwise, the color is not available for animation.
		/// </summary>
		PC_RESERVED = 0x1,
	}

	/// <summary>The <c>LOGPALETTE</c> structure defines a logical palette.</summary>
	/// <remarks>
	/// The colors in the palette-entry table should appear in order of importance because entries earlier in the logical palette are
	/// most likely to be placed in the system palette.
	/// </remarks>
	// https://docs.microsoft.com/en-us/windows/desktop/api/wingdi/ns-wingdi-taglogpalette typedef struct tagLOGPALETTE { WORD
	// palVersion; WORD palNumEntries; PALETTEENTRY palPalEntry[1]; } LOGPALETTE, *PLOGPALETTE, *NPLOGPALETTE, *LPLOGPALETTE;
	[PInvokeData("wingdi.h", MSDNShortId = "99d70a0e-ac61-4a88-a500-66443e7882ad")]
	[StructLayout(LayoutKind.Sequential)]
	public class LOGPALETTE : IDisposable
	{
		/// <summary>The version number of the system.</summary>
		public ushort palVersion;

		/// <summary>The number of entries in the logical palette.</summary>
		public ushort palNumEntries;

		private IntPtr _palPalEntry;

		/// <summary>Specifies an array of PALETTEENTRY structures that define the color and usage of each entry in the logical palette.</summary>
		public PALETTEENTRY[] palPalEntry
		{
			get => _palPalEntry.ToArray<PALETTEENTRY>(palNumEntries);
			set { Marshal.FreeHGlobal(_palPalEntry); value.MarshalToPtr<PALETTEENTRY>(Marshal.AllocHGlobal, out _); }
		}

		/// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
		void IDisposable.Dispose() => Marshal.FreeHGlobal(_palPalEntry);
	}

	/// <summary>Specifies the color and usage of an entry in a logical palette.</summary>
	// https://docs.microsoft.com/en-us/windows/desktop/api/wingdi/ns-wingdi-tagpaletteentry typedef struct tagPALETTEENTRY { BYTE peRed;
	// BYTE peGreen; BYTE peBlue; BYTE peFlags; } PALETTEENTRY, *PPALETTEENTRY, *LPPALETTEENTRY;
	[PInvokeData("wingdi.h")]
	[StructLayout(LayoutKind.Sequential)]
	public struct PALETTEENTRY
	{
		/// <summary>
		/// <para>Type: <c>BYTE</c></para>
		/// <para>The red intensity value for the palette entry.</para>
		/// </summary>
		public byte peRed;

		/// <summary>
		/// <para>Type: <c>BYTE</c></para>
		/// <para>The green intensity value for the palette entry.</para>
		/// </summary>
		public byte peGreen;

		/// <summary>
		/// <para>Type: <c>BYTE</c></para>
		/// <para>The blue intensity value for the palette entry.</para>
		/// </summary>
		public byte peBlue;

		/// <summary>
		/// <para>Type: <c>BYTE</c></para>
		/// <para>
		/// The alpha intensity value for the palette entry. Note that as of DirectX 8, this member is treated differently than
		/// documented for Windows.
		/// </para>
		/// </summary>
		public PC peFlags;
	}
}