// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <array>

// This file looks like a unit test, but it contains benchmarks and test
// utilities intended for manual evaluation of the scalers in
// gl_helper*. These tests produce output in the form of files and printouts,
// but cannot really "fail". There is no point in making these tests part
// of any test automation run.

#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
#include <GLES2/gl2extchromium.h>
#include <stddef.h>
#include <stdio.h>

#include <cmath>
#include <memory>
#include <string>
#include <vector>

#include "base/at_exit.h"
#include "base/command_line.h"
#include "base/memory/raw_ptr.h"
#include "base/run_loop.h"
#include "base/strings/stringprintf.h"
#include "base/test/task_environment.h"
#include "base/time/time.h"
#include "components/viz/test/test_gpu_service_holder.h"
#include "gpu/command_buffer/client/gl_helper.h"
#include "gpu/command_buffer/client/gl_helper_scaling.h"
#include "gpu/command_buffer/client/gles2_implementation.h"
#include "gpu/command_buffer/client/shared_memory_limits.h"
#include "gpu/ipc/gl_in_process_context.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/gfx/codec/png_codec.h"

namespace gpu {

namespace {

constexpr auto kQualities = std::to_array<GLHelper::ScalerQuality>({
    GLHelper::SCALER_QUALITY_BEST,
    GLHelper::SCALER_QUALITY_GOOD,
    GLHelper::SCALER_QUALITY_FAST,
});

constexpr auto kQualityNames = std::to_array<const char*>({
    "best",
    "good",
    "fast",
});

}  // namespace

class GLHelperBenchmark : public testing::Test {
 protected:
  void SetUp() override {
    context_ = std::make_unique<GLInProcessContext>();
    auto result = context_->Initialize(
        viz::TestGpuServiceHolder::GetInstance()->task_executor());
    DCHECK_EQ(result, ContextResult::kSuccess);
    gl_ = context_->GetImplementation();
    ContextSupport* support = context_->GetImplementation();

    helper_ = std::make_unique<GLHelper>(gl_, support);
    helper_scaling_ = std::make_unique<GLHelperScaling>(gl_, helper_.get());
  }

  void TearDown() override {
    helper_scaling_.reset(nullptr);
    helper_.reset(nullptr);
    gl_ = nullptr;
    context_.reset(nullptr);
  }

  base::test::TaskEnvironment task_environment_;
  std::unique_ptr<GLInProcessContext> context_;
  raw_ptr<gles2::GLES2Interface> gl_;  // This is owned by |context_|.
  std::unique_ptr<GLHelper> helper_;
  std::unique_ptr<GLHelperScaling> helper_scaling_;
  base::circular_deque<GLHelperScaling::ScaleOp> x_ops_, y_ops_;
};

TEST_F(GLHelperBenchmark, ScaleBenchmark) {
  auto output_sizes = std::to_array<int>({
      1920,
      1080,
      1249,
      720,  // Output size on pixel
      256,
      144,
  });
  auto input_sizes = std::to_array<int>({
      3200,
      2040,
      2560,
      1476,  // Pixel tab size
      1920,
      1080,
      1280,
      720,
      800,
      480,
      256,
      144,
  });

  for (size_t q = 0; q < std::size(kQualities); q++) {
    for (size_t outsize = 0; outsize < std::size(output_sizes); outsize += 2) {
      for (size_t insize = 0; insize < std::size(input_sizes); insize += 2) {
        uint32_t src_texture;
        gl_->GenTextures(1, &src_texture);
        uint32_t dst_texture;
        gl_->GenTextures(1, &dst_texture);
        uint32_t framebuffer;
        gl_->GenFramebuffers(1, &framebuffer);
        const gfx::Size src_size(input_sizes[insize], input_sizes[insize + 1]);
        const gfx::Size dst_size(output_sizes[outsize],
                                 output_sizes[outsize + 1]);
        SkBitmap input;
        input.allocN32Pixels(src_size.width(), src_size.height());

        SkBitmap output_pixels;
        output_pixels.allocN32Pixels(dst_size.width(), dst_size.height());

        gl_->BindFramebuffer(GL_FRAMEBUFFER, framebuffer);
        gl_->BindTexture(GL_TEXTURE_2D, dst_texture);
        gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, dst_size.width(),
                        dst_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                        nullptr);
        gl_->BindTexture(GL_TEXTURE_2D, src_texture);
        gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, src_size.width(),
                        src_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                        input.getPixels());

        std::unique_ptr<GLHelper::ScalerInterface> scaler =
            helper_->CreateScaler(
                kQualities[q],
                gfx::Vector2d(src_size.width(), src_size.height()),
                gfx::Vector2d(dst_size.width(), dst_size.height()), false,
                false, false);
        // Scale once beforehand before we start measuring.
        const gfx::Rect output_rect(dst_size);
        scaler->Scale(src_texture, src_size, gfx::Vector2dF(), dst_texture,
                      output_rect);
        gl_->Finish();

        base::TimeTicks start_time = base::TimeTicks::Now();
        int iterations = 0;
        base::TimeTicks end_time;
        while (true) {
          for (int i = 0; i < 50; i++) {
            iterations++;
            scaler->Scale(src_texture, src_size, gfx::Vector2dF(), dst_texture,
                          output_rect);
            gl_->Flush();
          }
          gl_->Finish();
          end_time = base::TimeTicks::Now();
          if (iterations > 2000) {
            break;
          }
          if ((end_time - start_time) > base::Seconds(1)) {
            break;
          }
        }
        gl_->DeleteTextures(1, &dst_texture);
        gl_->DeleteTextures(1, &src_texture);
        gl_->DeleteFramebuffers(1, &framebuffer);

        std::string name;
        name = base::StringPrintf("scale_%dx%d_to_%dx%d_%s", src_size.width(),
                                  src_size.height(), dst_size.width(),
                                  dst_size.height(), kQualityNames[q]);

        float ms = (end_time - start_time).InMillisecondsF() / iterations;
        VLOG(0) << base::StringPrintf("*RESULT gpu_scale_time: %s=%.2f ms\n",
                                      name.c_str(), ms);
      }
    }
  }
}

}  // namespace gpu