// 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 "SampleUtils.h"

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

#include <vector>

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 =
        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 = 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.depth = 1;
    descriptor.arrayLayerCount = 1;
    descriptor.sampleCount = 1;
    descriptor.format = wgpu::TextureFormat::RGBA8Unorm;
    descriptor.mipLevelCount = 1;
    descriptor.usage = wgpu::TextureUsage::CopyDst | wgpu::TextureUsage::Sampled;
    texture = device.CreateTexture(&descriptor);

    wgpu::SamplerDescriptor samplerDesc = utils::GetDefaultSamplerDescriptor();
    sampler = device.CreateSampler(&samplerDesc);

    // 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 = utils::CreateBufferFromData(
        device, data.data(), static_cast<uint32_t>(data.size()), wgpu::BufferUsage::CopySrc);
    wgpu::BufferCopyView bufferCopyView = utils::CreateBufferCopyView(stagingBuffer, 0, 0, 0);
    wgpu::TextureCopyView textureCopyView = utils::CreateTextureCopyView(texture, 0, 0, {0, 0, 0});
    wgpu::Extent3D copySize = {1024, 1024, 1};

    wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
    encoder.CopyBufferToTexture(&bufferCopyView, &textureCopyView, &copySize);

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

void init() {
    device = CreateCppDawnDevice();

    queue = device.CreateQueue();
    swapchain = GetSwapChain(device);
    swapchain.Configure(GetPreferredSwapChainTextureFormat(), wgpu::TextureUsage::OutputAttachment,
                        640, 480);

    initBuffers();
    initTextures();

    wgpu::ShaderModule vsModule =
        utils::CreateShaderModule(device, utils::SingleShaderStage::Vertex, R"(
        #version 450
        layout(location = 0) in vec4 pos;
        void main() {
            gl_Position = pos;
        })");

    wgpu::ShaderModule fsModule =
        utils::CreateShaderModule(device, utils::SingleShaderStage::Fragment, R"(
        #version 450
        layout(set = 0, binding = 0) uniform sampler mySampler;
        layout(set = 0, binding = 1) uniform texture2D myTexture;

        layout(location = 0) out vec4 fragColor;
        void main() {
            fragColor = texture(sampler2D(myTexture, mySampler), gl_FragCoord.xy / vec2(640.0, 480.0));
        })");

    auto bgl = utils::MakeBindGroupLayout(
        device, {
                    {0, wgpu::ShaderStage::Fragment, wgpu::BindingType::Sampler},
                    {1, wgpu::ShaderStage::Fragment, wgpu::BindingType::SampledTexture},
                });

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

    depthStencilView = CreateDefaultDepthStencilView(device);

    utils::ComboRenderPipelineDescriptor descriptor(device);
    descriptor.layout = utils::MakeBasicPipelineLayout(device, &bgl);
    descriptor.vertexStage.module = vsModule;
    descriptor.cFragmentStage.module = fsModule;
    descriptor.cVertexState.vertexBufferCount = 1;
    descriptor.cVertexState.cVertexBuffers[0].arrayStride = 4 * sizeof(float);
    descriptor.cVertexState.cVertexBuffers[0].attributeCount = 1;
    descriptor.cVertexState.cAttributes[0].format = wgpu::VertexFormat::Float4;
    descriptor.depthStencilState = &descriptor.cDepthStencilState;
    descriptor.cDepthStencilState.format = wgpu::TextureFormat::Depth24PlusStencil8;
    descriptor.cColorStates[0].format = GetPreferredSwapChainTextureFormat();

    pipeline = device.CreateRenderPipeline(&descriptor);

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

    bindGroup = 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();
    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);
        pass.DrawIndexed(3);
        pass.EndPass();
    }

    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()) {
        frame();
        utils::USleep(16000);
    }

    // TODO release stuff
}