//
// Copyright 2019 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// ClearPerf:
//   Performance test for clearing framebuffers.
//

#include "ANGLEPerfTest.h"

#include <iostream>
#include <random>
#include <sstream>

#include "test_utils/ANGLETest.h"
#include "test_utils/gl_raii.h"
#include "util/random_utils.h"
#include "util/shader_utils.h"

using namespace angle;

namespace
{
constexpr unsigned int kIterationsPerStep = 256;

struct ClearParams final : public RenderTestParams
{
    ClearParams()
    {
        iterationsPerStep = kIterationsPerStep;
        trackGpuTime      = true;

        fboSize = 2048;

        internalFormat = GL_RGBA8;

        scissoredClear = false;
    }

    std::string story() const override;

    GLsizei fboSize;
    GLsizei textureSize;

    GLenum internalFormat;

    bool scissoredClear;
};

std::ostream &operator<<(std::ostream &os, const ClearParams &params)
{
    os << params.backendAndStory().substr(1);
    return os;
}

std::string ClearParams::story() const
{
    std::stringstream strstr;

    strstr << RenderTestParams::story();

    if (internalFormat == GL_RGB8)
    {
        strstr << "_rgb";
    }

    if (scissoredClear)
    {
        strstr << "_scissoredClear";
    }

    return strstr.str();
}

class ClearBenchmark : public ANGLERenderTest, public ::testing::WithParamInterface<ClearParams>
{
  public:
    ClearBenchmark();

    void initializeBenchmark() override;
    void destroyBenchmark() override;
    void drawBenchmark() override;

  private:
    void initShaders();

    std::vector<GLuint> mTextures;

    GLuint mProgram;
};

ClearBenchmark::ClearBenchmark() : ANGLERenderTest("Clear", GetParam()), mProgram(0u)
{
    // Crashes on nvidia+d3d11. http://crbug.com/945415
    if (GetParam().getRenderer() == EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE)
    {
        mSkipTest = true;
    }
}

void ClearBenchmark::initializeBenchmark()
{
    initShaders();
    glViewport(0, 0, getWindow()->getWidth(), getWindow()->getHeight());

    ASSERT_GL_NO_ERROR();
}

void ClearBenchmark::initShaders()
{
    constexpr char kVS[] = R"(void main()
{
    gl_Position = vec4(0, 0, 0, 1);
})";

    constexpr char kFS[] = R"(precision mediump float;
void main()
{
    gl_FragColor = vec4(0);
})";

    mProgram = CompileProgram(kVS, kFS);
    ASSERT_NE(0u, mProgram);

    glUseProgram(mProgram);

    glDisable(GL_DEPTH_TEST);

    ASSERT_GL_NO_ERROR();
}

void ClearBenchmark::destroyBenchmark()
{
    glDeleteProgram(mProgram);
}

void ClearBenchmark::drawBenchmark()
{
    const auto &params = GetParam();

    GLRenderbuffer colorRbo;
    glBindRenderbuffer(GL_RENDERBUFFER, colorRbo);
    glRenderbufferStorage(GL_RENDERBUFFER, params.internalFormat, params.fboSize, params.fboSize);

    GLRenderbuffer depthRbo;
    glBindRenderbuffer(GL_RENDERBUFFER, depthRbo);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, params.fboSize, params.fboSize);

    GLFramebuffer fbo;
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRbo);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRbo);

    glViewport(0, 0, params.fboSize, params.fboSize);
    glDisable(GL_SCISSOR_TEST);

    startGpuTimer();

    if (params.scissoredClear)
    {
        angle::RNG rng;
        const GLuint width  = params.fboSize;
        const GLuint height = params.fboSize;
        for (GLuint index = 0; index < (width - 1) / 2; index++)
        {
            // Do the first clear without the scissor.
            if (index > 0)
            {
                glEnable(GL_SCISSOR_TEST);
                glScissor(index, index, width - (index * 2), height - (index * 2));
            }

            GLColor color      = RandomColor(&rng);
            Vector4 floatColor = color.toNormalizedVector();
            glClearColor(floatColor[0], floatColor[1], floatColor[2], floatColor[3]);
            glClear(GL_COLOR_BUFFER_BIT);
        }
    }
    else
    {
        for (size_t it = 0; it < params.iterationsPerStep; ++it)
        {
            float clearValue = (it % 2) * 0.5f + 0.2f;
            glClearColor(clearValue, clearValue, clearValue, clearValue);
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
            glDrawArrays(GL_TRIANGLES, 0, 3);
        }
    }

    stopGpuTimer();

    ASSERT_GL_NO_ERROR();
}

ClearParams D3D11Params()
{
    ClearParams params;
    params.eglParameters = egl_platform::D3D11();
    return params;
}

ClearParams OpenGLOrGLESParams()
{
    ClearParams params;
    params.eglParameters = egl_platform::OPENGL_OR_GLES();
    return params;
}

ClearParams VulkanParams(bool emulatedFormat, bool scissoredClear)
{
    ClearParams params;
    params.eglParameters = egl_platform::VULKAN();
    if (emulatedFormat)
    {
        params.internalFormat = GL_RGB8;
    }
    params.scissoredClear = scissoredClear;
    return params;
}

}  // anonymous namespace

TEST_P(ClearBenchmark, Run)
{
    run();
}

ANGLE_INSTANTIATE_TEST(ClearBenchmark,
                       D3D11Params(),
                       OpenGLOrGLESParams(),
                       VulkanParams(false, false),
                       VulkanParams(true, false),
                       VulkanParams(false, true));