using System.Threading;

namespace Sandbox.Resources;

public abstract class TextureGenerator : ResourceGenerator<Texture>
{
	/// <summary>
	/// Find an existing texture for this
	/// </summary>
	protected virtual ValueTask<Texture> CreateTexture( Options options, CancellationToken ct )
	{
		return default;
	}

	/// <summary>
	/// Create a texture. Will replace a placeholder texture, which will turn into the generated texture later, if it's not immediately available.
	/// </summary>
	public sealed override Texture Create( Options options )
	{
		var tex = CreateTexture( options, default );

		Texture output = default;
		if ( !tex.IsCompletedSuccessfully )
		{
			// loading async
			output = Texture.Create( 1, 1 ).WithData( new byte[4] { 0, 0, 0, 0 } ).Finish();
			_ = output.ReplacementAsync( tex.AsTask() );
		}
		else
		{
			// finished immediately
			output = tex.Result;
		}

		if ( output is null ) return default;

		output.EmbeddedResource = CreateEmbeddedResource();
		return output;
	}

	/// <summary>
	/// Create a texture. Will wait until the texture is fully loaded and return when done.
	/// </summary>
	public sealed override async ValueTask<Texture> CreateAsync( Options options, CancellationToken token )
	{
		// Call it completely in a new thread
		var output = await Task.Run( async () => await CreateTexture( options, token ) );
		if ( output is null ) return default;

		token.ThrowIfCancellationRequested();

		output.EmbeddedResource = CreateEmbeddedResource();
		return output;
	}

	public virtual EmbeddedResource? CreateEmbeddedResource()
	{
		return new EmbeddedResource
		{
			ResourceCompiler = "texture",
			ResourceGenerator = DisplayInfo.For( this ).ClassName ?? GetType().FullName,
			Data = Json.SerializeAsObject( this )
		};
	}

}