// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#import "flutter/shell/platform/darwin/ios/ios_surface_metal_impeller.h"

#include "flutter/impeller/renderer/backend/metal/formats_mtl.h"
#include "flutter/impeller/renderer/context.h"
#include "flutter/shell/gpu/gpu_surface_metal_impeller.h"

namespace flutter {

static impeller::PixelFormat InferOffscreenLayerPixelFormat(impeller::PixelFormat pixel_format) {
  switch (pixel_format) {
    case impeller::PixelFormat::kB10G10R10XR:
      return impeller::PixelFormat::kB10G10R10A10XR;
    default:
      return pixel_format;
  }
}

IOSSurfaceMetalImpeller::IOSSurfaceMetalImpeller(const fml::scoped_nsobject<CAMetalLayer>& layer,
                                                 const std::shared_ptr<IOSContext>& context)
    : IOSSurface(context),
      GPUSurfaceMetalDelegate(MTLRenderTargetType::kCAMetalLayer),
      layer_(layer),
      impeller_context_(context ? context->GetImpellerContext() : nullptr) {
  if (!impeller_context_) {
    return;
  }
  is_valid_ = true;
}

// |IOSSurface|
IOSSurfaceMetalImpeller::~IOSSurfaceMetalImpeller() = default;

// |IOSSurface|
bool IOSSurfaceMetalImpeller::IsValid() const {
  return is_valid_;
}

// |IOSSurface|
void IOSSurfaceMetalImpeller::UpdateStorageSizeIfNecessary() {
  // Nothing to do.
}

// |IOSSurface|
std::unique_ptr<Surface> IOSSurfaceMetalImpeller::CreateGPUSurface(GrDirectContext*) {
  impeller_context_->UpdateOffscreenLayerPixelFormat(
      InferOffscreenLayerPixelFormat(impeller::FromMTLPixelFormat(layer_.get().pixelFormat)));
  return std::make_unique<GPUSurfaceMetalImpeller>(this,              //
                                                   impeller_context_  //
  );
}

// |GPUSurfaceMetalDelegate|
GPUCAMetalLayerHandle IOSSurfaceMetalImpeller::GetCAMetalLayer(const SkISize& frame_info) const {
  CAMetalLayer* layer = layer_.get();
  const auto drawable_size = CGSizeMake(frame_info.width(), frame_info.height());
  if (!CGSizeEqualToSize(drawable_size, layer.drawableSize)) {
    layer.drawableSize = drawable_size;
  }

  // Flutter needs to read from the color attachment in cases where there are effects such as
  // backdrop filters. Flutter plugins that create platform views may also read from the layer.
  layer.framebufferOnly = NO;

  // When there are platform views in the scene, the drawable needs to be presented in the same
  // transaction as the one created for platform views. When the drawable are being presented from
  // the raster thread, there is no such transaction.
  layer.presentsWithTransaction = [[NSThread currentThread] isMainThread];

  return layer;
}

// |GPUSurfaceMetalDelegate|
bool IOSSurfaceMetalImpeller::PresentDrawable(GrMTLHandle drawable) const {
  FML_DCHECK(false);
  return false;
}

// |GPUSurfaceMetalDelegate|
GPUMTLTextureInfo IOSSurfaceMetalImpeller::GetMTLTexture(const SkISize& frame_info) const {
  FML_CHECK(false);
  return GPUMTLTextureInfo{
      .texture_id = -1,   //
      .texture = nullptr  //
  };
}

// |GPUSurfaceMetalDelegate|
bool IOSSurfaceMetalImpeller::PresentTexture(GPUMTLTextureInfo texture) const {
  FML_CHECK(false);
  return false;
}

// |GPUSurfaceMetalDelegate|
bool IOSSurfaceMetalImpeller::AllowsDrawingWhenGpuDisabled() const {
  return false;
}

}  // namespace flutter