// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using SixLabors.ImageSharp.Drawing.Processing.Backends;
using SixLabors.ImageSharp.Processing;

namespace SixLabors.ImageSharp.Drawing.Processing {
  /// <summary>
  /// Adds extensions that allow configuring the drawing backend implementation.
  /// </summary>
  public static class RasterizerDefaultsExtensions
  {
      /// <summary>
      /// Sets the drawing backend against the source image processing context.
      /// </summary>
      /// <param name="context">The image processing context to store the backend against.</param>
      /// <param name="backend">The backend to use.</param>
      /// <returns>The passed in <paramref name="context"/> to allow chaining.</returns>
      internal static IImageProcessingContext SetDrawingBackend(this IImageProcessingContext context, IDrawingBackend backend)
      {
          Guard.NotNull(backend, nameof(backend));
          context.Properties[typeof(IDrawingBackend)] = backend;

          return context;
      }

      /// <summary>
      /// Sets the default drawing backend against the configuration.
      /// </summary>
      /// <param name="configuration">The configuration to store the backend against.</param>
      /// <param name="backend">The backend to use.</param>
      public static void SetDrawingBackend(this Configuration configuration, IDrawingBackend backend)
      {
          Guard.NotNull(backend, nameof(backend));
          configuration.Properties[typeof(IDrawingBackend)] = backend;
      }

      /// <summary>
      /// Gets the drawing backend from the source image processing context.
      /// </summary>
      /// <param name="context">The image processing context to retrieve the backend from.</param>
      /// <returns>The configured backend.</returns>
      internal static IDrawingBackend GetDrawingBackend(this IImageProcessingContext context)
      {
          if (context.Properties.TryGetValue(typeof(IDrawingBackend), out object? backend) &&
              backend is IDrawingBackend configured)
          {
              return configured;
          }

          return context.Configuration.GetDrawingBackend();
      }

      /// <summary>
      /// Gets the default drawing backend from the configuration.
      /// </summary>
      /// <param name="configuration">The configuration to retrieve the backend from.</param>
      /// <returns>The configured backend.</returns>
      internal static IDrawingBackend GetDrawingBackend(this Configuration configuration)
      {
          if (configuration.Properties.TryGetValue(typeof(IDrawingBackend), out object? backend) &&
              backend is IDrawingBackend configured)
          {
              return configured;
          }

          IDrawingBackend defaultBackend = DefaultDrawingBackend.Instance;
          configuration.Properties[typeof(IDrawingBackend)] = defaultBackend;
          return defaultBackend;
      }
  }
}