// 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/DawnHelpers.h"
#include "utils/SystemUtils.h"

#include <vector>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

dawn::Device device;

dawn::Buffer indexBuffer;
dawn::Buffer vertexBuffer;
dawn::Buffer planeBuffer;
dawn::Buffer cameraBuffer;
dawn::Buffer transformBuffer[2];

dawn::BindGroup cameraBindGroup;
dawn::BindGroup bindGroup[2];
dawn::BindGroup cubeTransformBindGroup[2];

dawn::Queue queue;
dawn::SwapChain swapchain;
dawn::TextureView depthStencilView;
dawn::RenderPipeline pipeline;
dawn::RenderPipeline planePipeline;
dawn::RenderPipeline reflectionPipeline;

void initBuffers() {
    static const uint32_t indexData[6*6] = {
        0, 1, 2,
        0, 2, 3,

        4, 5, 6,
        4, 6, 7,

        8, 9, 10,
        8, 10, 11,

        12, 13, 14,
        12, 14, 15,

        16, 17, 18,
        16, 18, 19,

        20, 21, 22,
        20, 22, 23
    };
    indexBuffer = utils::CreateBufferFromData(device, indexData, sizeof(indexData), dawn::BufferUsageBit::Index);

    static const float vertexData[6 * 4 * 6] = {
        -1.0, -1.0,  1.0,    1.0, 0.0, 0.0,
        1.0, -1.0,  1.0,    1.0, 0.0, 0.0,
        1.0,  1.0,  1.0,    1.0, 0.0, 0.0,
        -1.0,  1.0,  1.0,    1.0, 0.0, 0.0,

        -1.0, -1.0, -1.0,    1.0, 1.0, 0.0,
        -1.0,  1.0, -1.0,    1.0, 1.0, 0.0,
        1.0,  1.0, -1.0,    1.0, 1.0, 0.0,
        1.0, -1.0, -1.0,    1.0, 1.0, 0.0,

        -1.0,  1.0, -1.0,    1.0, 0.0, 1.0,
        -1.0,  1.0,  1.0,    1.0, 0.0, 1.0,
        1.0,  1.0,  1.0,    1.0, 0.0, 1.0,
        1.0,  1.0, -1.0,    1.0, 0.0, 1.0,

        -1.0, -1.0, -1.0,    0.0, 1.0, 0.0,
        1.0, -1.0, -1.0,    0.0, 1.0, 0.0,
        1.0, -1.0,  1.0,    0.0, 1.0, 0.0,
        -1.0, -1.0,  1.0,    0.0, 1.0, 0.0,

        1.0, -1.0, -1.0,    0.0, 1.0, 1.0,
        1.0,  1.0, -1.0,    0.0, 1.0, 1.0,
        1.0,  1.0,  1.0,    0.0, 1.0, 1.0,
        1.0, -1.0,  1.0,    0.0, 1.0, 1.0,

        -1.0, -1.0, -1.0,    1.0, 1.0, 1.0,
        -1.0, -1.0,  1.0,    1.0, 1.0, 1.0,
        -1.0,  1.0,  1.0,    1.0, 1.0, 1.0,
        -1.0,  1.0, -1.0,    1.0, 1.0, 1.0
    };
    vertexBuffer = utils::CreateBufferFromData(device, vertexData, sizeof(vertexData), dawn::BufferUsageBit::Vertex);

    static const float planeData[6 * 4] = {
        -2.0, -1.0, -2.0,    0.5, 0.5, 0.5,
        2.0, -1.0, -2.0,    0.5, 0.5, 0.5,
        2.0, -1.0,  2.0,    0.5, 0.5, 0.5,
        -2.0, -1.0,  2.0,    0.5, 0.5, 0.5,
    };
    planeBuffer = utils::CreateBufferFromData(device, planeData, sizeof(planeData), dawn::BufferUsageBit::Vertex);
}

struct CameraData {
    glm::mat4 view;
    glm::mat4 proj;
} cameraData;

void init() {
    device = CreateCppDawnDevice();

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

    initBuffers();

    dawn::ShaderModule vsModule = utils::CreateShaderModule(device, utils::ShaderStage::Vertex, R"(
        #version 450
        layout(set = 0, binding = 0) uniform cameraData {
            mat4 view;
            mat4 proj;
        } camera;
        layout(set = 0, binding = 1) uniform modelData {
            mat4 modelMatrix;
        };
        layout(location = 0) in vec3 pos;
        layout(location = 1) in vec3 col;
        layout(location = 2) out vec3 f_col;
        void main() {
            f_col = col;
            gl_Position = camera.proj * camera.view * modelMatrix * vec4(pos, 1.0);
        })");

    dawn::ShaderModule fsModule =
        utils::CreateShaderModule(device, utils::ShaderStage::Fragment, R"(
        #version 450
        layout(location = 2) in vec3 f_col;
        layout(location = 0) out vec4 fragColor;
        void main() {
            fragColor = vec4(f_col, 1.0);
        })");

    dawn::ShaderModule fsReflectionModule =
        utils::CreateShaderModule(device, utils::ShaderStage::Fragment, R"(
        #version 450
        layout(location = 2) in vec3 f_col;
        layout(location = 0) out vec4 fragColor;
        void main() {
            fragColor = vec4(mix(f_col, vec3(0.5, 0.5, 0.5), 0.5), 1.0);
        })");

    utils::ComboVertexInputDescriptor vertexInput;
    vertexInput.cBuffers[0].attributeCount = 2;
    vertexInput.cAttributes[0].format = dawn::VertexFormat::Float3;
    vertexInput.cAttributes[1].shaderLocation = 1;
    vertexInput.cAttributes[1].offset = 3 * sizeof(float);
    vertexInput.cAttributes[1].format = dawn::VertexFormat::Float3;

    vertexInput.bufferCount = 1;
    vertexInput.cBuffers[0].stride = 6 * sizeof(float);

    auto bgl = utils::MakeBindGroupLayout(
        device, {
                    {0, dawn::ShaderStageBit::Vertex, dawn::BindingType::UniformBuffer},
                    {1, dawn::ShaderStageBit::Vertex, dawn::BindingType::UniformBuffer},
                });

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

    dawn::BufferDescriptor cameraBufDesc;
    cameraBufDesc.size = sizeof(CameraData);
    cameraBufDesc.usage = dawn::BufferUsageBit::CopyDst | dawn::BufferUsageBit::Uniform;
    cameraBuffer = device.CreateBuffer(&cameraBufDesc);

    glm::mat4 transform(1.0);
    transformBuffer[0] = utils::CreateBufferFromData(device, &transform, sizeof(glm::mat4), dawn::BufferUsageBit::Uniform);

    transform = glm::translate(transform, glm::vec3(0.f, -2.f, 0.f));
    transformBuffer[1] = utils::CreateBufferFromData(device, &transform, sizeof(glm::mat4), dawn::BufferUsageBit::Uniform);

    bindGroup[0] = utils::MakeBindGroup(device, bgl, {
        {0, cameraBuffer, 0, sizeof(CameraData)},
        {1, transformBuffer[0], 0, sizeof(glm::mat4)}
    });

    bindGroup[1] = utils::MakeBindGroup(device, bgl, {
        {0, cameraBuffer, 0, sizeof(CameraData)},
        {1, transformBuffer[1], 0, sizeof(glm::mat4)}
    });

    depthStencilView = CreateDefaultDepthStencilView(device);

    utils::ComboRenderPipelineDescriptor descriptor(device);
    descriptor.layout = pl;
    descriptor.cVertexStage.module = vsModule;
    descriptor.cFragmentStage.module = fsModule;
    descriptor.vertexInput = &vertexInput;
    descriptor.depthStencilState = &descriptor.cDepthStencilState;
    descriptor.cDepthStencilState.format = dawn::TextureFormat::Depth24PlusStencil8;
    descriptor.cColorStates[0]->format = GetPreferredSwapChainTextureFormat();
    descriptor.cDepthStencilState.depthWriteEnabled = true;
    descriptor.cDepthStencilState.depthCompare = dawn::CompareFunction::Less;

    pipeline = device.CreateRenderPipeline(&descriptor);

    utils::ComboRenderPipelineDescriptor pDescriptor(device);
    pDescriptor.layout = pl;
    pDescriptor.cVertexStage.module = vsModule;
    pDescriptor.cFragmentStage.module = fsModule;
    pDescriptor.vertexInput = &vertexInput;
    pDescriptor.depthStencilState = &pDescriptor.cDepthStencilState;
    pDescriptor.cDepthStencilState.format = dawn::TextureFormat::Depth24PlusStencil8;
    pDescriptor.cColorStates[0]->format = GetPreferredSwapChainTextureFormat();
    pDescriptor.cDepthStencilState.stencilFront.passOp = dawn::StencilOperation::Replace;
    pDescriptor.cDepthStencilState.stencilBack.passOp = dawn::StencilOperation::Replace;
    pDescriptor.cDepthStencilState.depthCompare = dawn::CompareFunction::Less;

    planePipeline = device.CreateRenderPipeline(&pDescriptor);

    utils::ComboRenderPipelineDescriptor rfDescriptor(device);
    rfDescriptor.layout = pl;
    rfDescriptor.cVertexStage.module = vsModule;
    rfDescriptor.cFragmentStage.module = fsReflectionModule;
    rfDescriptor.vertexInput = &vertexInput;
    rfDescriptor.depthStencilState = &rfDescriptor.cDepthStencilState;
    rfDescriptor.cDepthStencilState.format = dawn::TextureFormat::Depth24PlusStencil8;
    rfDescriptor.cColorStates[0]->format = GetPreferredSwapChainTextureFormat();
    rfDescriptor.cDepthStencilState.stencilFront.compare = dawn::CompareFunction::Equal;
    rfDescriptor.cDepthStencilState.stencilBack.compare = dawn::CompareFunction::Equal;
    rfDescriptor.cDepthStencilState.stencilFront.passOp = dawn::StencilOperation::Replace;
    rfDescriptor.cDepthStencilState.stencilBack.passOp = dawn::StencilOperation::Replace;
    rfDescriptor.cDepthStencilState.depthWriteEnabled = true;
    rfDescriptor.cDepthStencilState.depthCompare = dawn::CompareFunction::Less;

    reflectionPipeline = device.CreateRenderPipeline(&rfDescriptor);

    cameraData.proj = glm::perspective(glm::radians(45.0f), 1.f, 1.0f, 100.0f);
}

struct {uint32_t a; float b;} s;
void frame() {
    s.a = (s.a + 1) % 256;
    s.b += 0.01f;
    if (s.b >= 1.0f) {s.b = 0.0f;}
    static const uint64_t vertexBufferOffsets[1] = {0};

    cameraData.view = glm::lookAt(
        glm::vec3(8.f * std::sin(glm::radians(s.b * 360.f)), 2.f, 8.f * std::cos(glm::radians(s.b * 360.f))),
        glm::vec3(0.0f, 0.0f, 0.0f),
        glm::vec3(0.0f, -1.0f, 0.0f)
    );

    cameraBuffer.SetSubData(0, sizeof(CameraData), &cameraData);

    dawn::Texture backbuffer = swapchain.GetNextTexture();
    utils::ComboRenderPassDescriptor renderPass({backbuffer.CreateDefaultView()},
                                                depthStencilView);

    dawn::CommandEncoder encoder = device.CreateCommandEncoder();
    {
        dawn::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
        pass.SetPipeline(pipeline);
        pass.SetBindGroup(0, bindGroup[0], 0, nullptr);
        pass.SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets);
        pass.SetIndexBuffer(indexBuffer, 0);
        pass.DrawIndexed(36, 1, 0, 0, 0);

        pass.SetStencilReference(0x1);
        pass.SetPipeline(planePipeline);
        pass.SetBindGroup(0, bindGroup[0], 0, nullptr);
        pass.SetVertexBuffers(0, 1, &planeBuffer, vertexBufferOffsets);
        pass.DrawIndexed(6, 1, 0, 0, 0);

        pass.SetPipeline(reflectionPipeline);
        pass.SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets);
        pass.SetBindGroup(0, bindGroup[1], 0, nullptr);
        pass.DrawIndexed(36, 1, 0, 0, 0);

        pass.EndPass();
    }

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

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

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

    // TODO release stuff
}