using System;
using RefreshCS;

namespace MoonWorks.Graphics
{
	/// <summary>
	/// A render target is a structure that wraps a texture so that it can be rendered to.
	/// </summary>
	public class RenderTarget : GraphicsResource
	{
		public TextureSlice TextureSlice { get; }
		public TextureFormat Format => TextureSlice.Texture.Format;

		protected override Action<IntPtr, IntPtr, IntPtr> QueueDestroyFunction => Refresh.Refresh_QueueDestroyRenderTarget;

		/// <summary>
		/// Creates a render target backed by a texture.
		/// </summary>
		/// <param name="device">An initialized GraphicsDevice.</param>
		/// <param name="width">The width of the render target.</param>
		/// <param name="height">The height of the render target.</param>
		/// <param name="format">The format of the render target.</param>
		/// <param name="canBeSampled">Whether the render target can be used by a sampler.</param>
		/// <param name="sampleCount">The multisample count of the render target.</param>
		/// <param name="levelCount">The mip level of the render target.</param>
		/// <returns></returns>
		public static RenderTarget CreateBackedRenderTarget(
			GraphicsDevice device,
			uint width,
			uint height,
			TextureFormat format,
			bool canBeSampled,
			SampleCount sampleCount = SampleCount.One,
			uint levelCount = 1
		)
		{
			TextureUsageFlags flags = 0;

			if (
				format == TextureFormat.D16 ||
				format == TextureFormat.D32 ||
				format == TextureFormat.D16S8 ||
				format == TextureFormat.D32S8
			)
			{
				flags |= TextureUsageFlags.DepthStencilTarget;
			}
			else
			{
				flags |= TextureUsageFlags.ColorTarget;
			}

			if (canBeSampled)
			{
				flags |= TextureUsageFlags.Sampler;
			}

			var texture = Texture.CreateTexture2D(
				device,
				width,
				height,
				format,
				flags,
				sampleCount,
				levelCount
			);

			return new RenderTarget(device, new TextureSlice(texture), sampleCount);
		}

		/// <summary>
		/// Creates a render target using a texture slice and an optional sample count.
		/// </summary>
		/// <param name="device">An initialized GraphicsDevice.</param>
		/// <param name="textureSlice">The texture slice that will be rendered to.</param>
		/// <param name="sampleCount">The desired multisample count of the render target.</param>
		public RenderTarget(
			GraphicsDevice device,
			in TextureSlice textureSlice,
			SampleCount sampleCount = SampleCount.One
		) : base(device)
		{
			Handle = Refresh.Refresh_CreateRenderTarget(
				device.Handle,
				textureSlice.ToRefreshTextureSlice(),
				(Refresh.SampleCount) sampleCount
			);
			TextureSlice = textureSlice;
		}
	}
}