// Copyright 2017 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "tests/DawnTest.h"

#include "utils/ComboRenderPipelineDescriptor.h"
#include "utils/WGPUHelpers.h"

#include <array>

constexpr static unsigned int kRTSize = 16;

class DrawQuad {
  public:
    DrawQuad() {
    }
    DrawQuad(wgpu::Device device, const char* vsSource, const char* fsSource) : device(device) {
        vsModule = utils::CreateShaderModule(device, utils::SingleShaderStage::Vertex, vsSource);
        fsModule = utils::CreateShaderModule(device, utils::SingleShaderStage::Fragment, fsSource);

        pipelineLayout = utils::MakeBasicPipelineLayout(device, nullptr);
    }

    void Draw(wgpu::RenderPassEncoder* pass) {
        utils::ComboRenderPipelineDescriptor descriptor(device);
        descriptor.layout = pipelineLayout;
        descriptor.vertexStage.module = vsModule;
        descriptor.cFragmentStage.module = fsModule;

        auto renderPipeline = device.CreateRenderPipeline(&descriptor);

        pass->SetPipeline(renderPipeline);
        pass->Draw(6, 1, 0, 0);
    }

  private:
    wgpu::Device device;
    wgpu::ShaderModule vsModule = {};
    wgpu::ShaderModule fsModule = {};
    wgpu::PipelineLayout pipelineLayout = {};
};

class RenderPassLoadOpTests : public DawnTest {
  protected:
    void SetUp() override {
        DawnTest::SetUp();

        wgpu::TextureDescriptor descriptor;
        descriptor.dimension = wgpu::TextureDimension::e2D;
        descriptor.size.width = kRTSize;
        descriptor.size.height = kRTSize;
        descriptor.size.depth = 1;
        descriptor.sampleCount = 1;
        descriptor.format = wgpu::TextureFormat::RGBA8Unorm;
        descriptor.mipLevelCount = 1;
        descriptor.usage = wgpu::TextureUsage::OutputAttachment | wgpu::TextureUsage::CopySrc;
        renderTarget = device.CreateTexture(&descriptor);

        renderTargetView = renderTarget.CreateView();

        std::fill(expectZero.begin(), expectZero.end(), RGBA8::kZero);

        std::fill(expectGreen.begin(), expectGreen.end(), RGBA8::kGreen);

        std::fill(expectBlue.begin(), expectBlue.end(), RGBA8::kBlue);

        // draws a blue quad on the right half of the screen
        const char* vsSource = R"(
                #version 450
                void main() {
                    const vec2 pos[6] = vec2[6](
                        vec2(0, -1), vec2(1, -1), vec2(0, 1),
                        vec2(0,  1), vec2(1, -1), vec2(1, 1));
                    gl_Position = vec4(pos[gl_VertexIndex], 0.f, 1.f);
                }
                )";
        const char* fsSource = R"(
                #version 450
                layout(location = 0) out vec4 color;
                void main() {
                    color = vec4(0.f, 0.f, 1.f, 1.f);
                }
                )";
        blueQuad = DrawQuad(device, vsSource, fsSource);
    }

    wgpu::Texture renderTarget;
    wgpu::TextureView renderTargetView;

    std::array<RGBA8, kRTSize * kRTSize> expectZero;
    std::array<RGBA8, kRTSize * kRTSize> expectGreen;
    std::array<RGBA8, kRTSize * kRTSize> expectBlue;

    DrawQuad blueQuad = {};
};

// Tests clearing, loading, and drawing into color attachments
TEST_P(RenderPassLoadOpTests, ColorClearThenLoadAndDraw) {
    // Part 1: clear once, check to make sure it's cleared
    utils::ComboRenderPassDescriptor renderPassClearZero({renderTargetView});
    auto commandsClearZeroEncoder = device.CreateCommandEncoder();
    auto clearZeroPass = commandsClearZeroEncoder.BeginRenderPass(&renderPassClearZero);
    clearZeroPass.EndPass();
    auto commandsClearZero = commandsClearZeroEncoder.Finish();

    utils::ComboRenderPassDescriptor renderPassClearGreen({renderTargetView});
    renderPassClearGreen.cColorAttachments[0].clearColor = {0.0f, 1.0f, 0.0f, 1.0f};
    auto commandsClearGreenEncoder = device.CreateCommandEncoder();
    auto clearGreenPass = commandsClearGreenEncoder.BeginRenderPass(&renderPassClearGreen);
    clearGreenPass.EndPass();
    auto commandsClearGreen = commandsClearGreenEncoder.Finish();

    queue.Submit(1, &commandsClearZero);
    EXPECT_TEXTURE_RGBA8_EQ(expectZero.data(), renderTarget, 0, 0, kRTSize, kRTSize, 0, 0);

    queue.Submit(1, &commandsClearGreen);
    EXPECT_TEXTURE_RGBA8_EQ(expectGreen.data(), renderTarget, 0, 0, kRTSize, kRTSize, 0, 0);

    // Part 2: draw a blue quad into the right half of the render target, and check result
    utils::ComboRenderPassDescriptor renderPassLoad({renderTargetView});
    renderPassLoad.cColorAttachments[0].loadOp = wgpu::LoadOp::Load;
    wgpu::CommandBuffer commandsLoad;
    {
        auto encoder = device.CreateCommandEncoder();
        auto pass = encoder.BeginRenderPass(&renderPassLoad);
        blueQuad.Draw(&pass);
        pass.EndPass();
        commandsLoad = encoder.Finish();
    }

    queue.Submit(1, &commandsLoad);
    // Left half should still be green
    EXPECT_TEXTURE_RGBA8_EQ(expectGreen.data(), renderTarget, 0, 0, kRTSize / 2, kRTSize, 0, 0);
    // Right half should now be blue
    EXPECT_TEXTURE_RGBA8_EQ(expectBlue.data(), renderTarget, kRTSize / 2, 0, kRTSize / 2, kRTSize,
                            0, 0);
}

DAWN_INSTANTIATE_TEST(RenderPassLoadOpTests,
                      D3D12Backend(),
                      MetalBackend(),
                      OpenGLBackend(),
                      VulkanBackend());