// 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.

#include "flutter/shell/platform/embedder/tests/embedder_test_compositor_metal.h"

#include <utility>

#include "flutter/fml/logging.h"
#include "flutter/shell/platform/embedder/tests/embedder_assertions.h"
#include "third_party/skia/include/core/SkSurface.h"
#include "third_party/skia/include/gpu/ganesh/SkSurfaceGanesh.h"

namespace flutter {
namespace testing {

EmbedderTestCompositorMetal::EmbedderTestCompositorMetal(
    SkISize surface_size,
    sk_sp<GrDirectContext> context)
    : EmbedderTestCompositor(surface_size, std::move(context)) {}

EmbedderTestCompositorMetal::~EmbedderTestCompositorMetal() = default;

bool EmbedderTestCompositorMetal::UpdateOffscrenComposition(
    const FlutterLayer** layers,
    size_t layers_count) {
  last_composition_ = nullptr;

  const auto image_info = SkImageInfo::MakeN32Premul(surface_size_);

  auto surface =
      SkSurfaces::RenderTarget(context_.get(),            // context
                               skgpu::Budgeted::kNo,      // budgeted
                               image_info,                // image info
                               1,                         // sample count
                               kTopLeft_GrSurfaceOrigin,  // surface origin
                               nullptr,                   // surface properties
                               false                      // create mipmaps
      );

  if (!surface) {
    FML_LOG(ERROR) << "Could not update the off-screen composition.";
    return false;
  }

  auto canvas = surface->getCanvas();

  // This has to be transparent because we are going to be compositing this
  // sub-hierarchy onto the on-screen surface.
  canvas->clear(SK_ColorTRANSPARENT);

  for (size_t i = 0; i < layers_count; ++i) {
    const auto* layer = layers[i];

    sk_sp<SkImage> platform_rendered_contents;

    sk_sp<SkImage> layer_image;
    SkIPoint canvas_offset = SkIPoint::Make(0, 0);

    switch (layer->type) {
      case kFlutterLayerContentTypeBackingStore:
        layer_image =
            reinterpret_cast<SkSurface*>(layer->backing_store->user_data)
                ->makeImageSnapshot();
        break;
      case kFlutterLayerContentTypePlatformView:
        layer_image =
            platform_view_renderer_callback_
                ? platform_view_renderer_callback_(*layer, context_.get())
                : nullptr;
        canvas_offset = SkIPoint::Make(layer->offset.x, layer->offset.y);
        break;
    };

    // If the layer is not a platform view but the engine did not specify an
    // image for the backing store, it is an error.
    if (!layer_image && layer->type != kFlutterLayerContentTypePlatformView) {
      FML_LOG(ERROR) << "Could not snapshot layer in test compositor: "
                     << *layer;
      return false;
    }

    // The test could have just specified no contents to be rendered in place of
    // a platform view. This is not an error.
    if (layer_image) {
      // The image rendered by Flutter already has the correct offset and
      // transformation applied. The layers offset is meant for the platform.
      canvas->drawImage(layer_image.get(), canvas_offset.x(),
                        canvas_offset.y());
    }
  }

  last_composition_ = surface->makeImageSnapshot();

  if (!last_composition_) {
    FML_LOG(ERROR) << "Could not update the contents of the sub-composition.";
    return false;
  }

  if (next_scene_callback_) {
    auto last_composition_snapshot = last_composition_->makeRasterImage();
    FML_CHECK(last_composition_snapshot);
    auto callback = next_scene_callback_;
    next_scene_callback_ = nullptr;
    callback(std::move(last_composition_snapshot));
  }

  return true;
}

}  // namespace testing
}  // namespace flutter