// 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 <vector>

#include "dawn/samples/SampleUtils.h"

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

wgpu::Device device;

wgpu::Buffer indexBuffer;
wgpu::Buffer vertexBuffer;

wgpu::Texture texture;
wgpu::Sampler sampler;

wgpu::Queue queue;
wgpu::SwapChain swapchain;
wgpu::TextureView depthStencilView;
wgpu::RenderPipeline pipeline;
wgpu::BindGroup bindGroup;

void initBuffers() {
    static const uint32_t indexData[3] = {
        0,
        1,
        2,
    };
    indexBuffer = dawn::utils::CreateBufferFromData(device, indexData, sizeof(indexData),
                                                    wgpu::BufferUsage::Index);

    static const float vertexData[12] = {
        0.0f, 0.5f, 0.0f, 1.0f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, 0.0f, 1.0f,
    };
    vertexBuffer = dawn::utils::CreateBufferFromData(device, vertexData, sizeof(vertexData),
                                                     wgpu::BufferUsage::Vertex);
}

void initTextures() {
    wgpu::TextureDescriptor descriptor;
    descriptor.dimension = wgpu::TextureDimension::e2D;
    descriptor.size.width = 1024;
    descriptor.size.height = 1024;
    descriptor.size.depthOrArrayLayers = 1;
    descriptor.sampleCount = 1;
    descriptor.format = wgpu::TextureFormat::RGBA8Unorm;
    descriptor.mipLevelCount = 1;
    descriptor.usage = wgpu::TextureUsage::CopyDst | wgpu::TextureUsage::TextureBinding;
    texture = device.CreateTexture(&descriptor);

    sampler = device.CreateSampler();

    // Initialize the texture with arbitrary data until we can load images
    std::vector<uint8_t> data(4 * 1024 * 1024, 0);
    for (size_t i = 0; i < data.size(); ++i) {
        data[i] = static_cast<uint8_t>(i % 253);
    }

    wgpu::Buffer stagingBuffer = dawn::utils::CreateBufferFromData(
        device, data.data(), static_cast<uint32_t>(data.size()), wgpu::BufferUsage::CopySrc);
    wgpu::ImageCopyBuffer imageCopyBuffer =
        dawn::utils::CreateImageCopyBuffer(stagingBuffer, 0, 4 * 1024);
    wgpu::ImageCopyTexture imageCopyTexture =
        dawn::utils::CreateImageCopyTexture(texture, 0, {0, 0, 0});
    wgpu::Extent3D copySize = {1024, 1024, 1};

    wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
    encoder.CopyBufferToTexture(&imageCopyBuffer, &imageCopyTexture, &copySize);

    wgpu::CommandBuffer copy = encoder.Finish();
    queue.Submit(1, &copy);
}

void init() {
    device = CreateCppDawnDevice();

    queue = device.GetQueue();
    swapchain = GetSwapChain();

    initBuffers();
    initTextures();

    wgpu::ShaderModule vsModule = dawn::utils::CreateShaderModule(device, R"(
        @vertex fn main(@location(0) pos : vec4f)
                            -> @builtin(position) vec4f {
            return pos;
        })");

    wgpu::ShaderModule fsModule = dawn::utils::CreateShaderModule(device, R"(
        @group(0) @binding(0) var mySampler: sampler;
        @group(0) @binding(1) var myTexture : texture_2d<f32>;

        @fragment fn main(@builtin(position) FragCoord : vec4f)
                              -> @location(0) vec4f {
            return textureSample(myTexture, mySampler, FragCoord.xy / vec2f(640.0, 480.0));
        })");

    auto bgl = dawn::utils::MakeBindGroupLayout(
        device, {
                    {0, wgpu::ShaderStage::Fragment, wgpu::SamplerBindingType::Filtering},
                    {1, wgpu::ShaderStage::Fragment, wgpu::TextureSampleType::Float},
                });

    wgpu::PipelineLayout pl = dawn::utils::MakeBasicPipelineLayout(device, &bgl);

    depthStencilView = CreateDefaultDepthStencilView(device);

    dawn::utils::ComboRenderPipelineDescriptor descriptor;
    descriptor.layout = dawn::utils::MakeBasicPipelineLayout(device, &bgl);
    descriptor.vertex.module = vsModule;
    descriptor.vertex.bufferCount = 1;
    descriptor.cBuffers[0].arrayStride = 4 * sizeof(float);
    descriptor.cBuffers[0].attributeCount = 1;
    descriptor.cAttributes[0].format = wgpu::VertexFormat::Float32x4;
    descriptor.cFragment.module = fsModule;
    descriptor.cTargets[0].format = GetPreferredSwapChainTextureFormat();
    descriptor.EnableDepthStencil(wgpu::TextureFormat::Depth24PlusStencil8);

    pipeline = device.CreateRenderPipeline(&descriptor);

    wgpu::TextureView view = texture.CreateView();

    bindGroup = dawn::utils::MakeBindGroup(device, bgl, {{0, sampler}, {1, view}});
}

struct {
    uint32_t a;
    float b;
} s;
void frame() {
    s.a = (s.a + 1) % 256;
    s.b += 0.02f;
    if (s.b >= 1.0f) {
        s.b = 0.0f;
    }

    wgpu::TextureView backbufferView = swapchain.GetCurrentTextureView();
    dawn::utils::ComboRenderPassDescriptor renderPass({backbufferView}, depthStencilView);

    wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
    {
        wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
        pass.SetPipeline(pipeline);
        pass.SetBindGroup(0, bindGroup);
        pass.SetVertexBuffer(0, vertexBuffer);
        pass.SetIndexBuffer(indexBuffer, wgpu::IndexFormat::Uint32);
        pass.DrawIndexed(3);
        pass.End();
    }

    wgpu::CommandBuffer commands = encoder.Finish();
    queue.Submit(1, &commands);
    swapchain.Present();
    DoFlush();
}

int main(int argc, const char* argv[]) {
    if (!InitSample(argc, argv)) {
        return 1;
    }
    init();

    while (!ShouldQuit()) {
        ProcessEvents();
        frame();
        dawn::utils::USleep(16000);
    }
}