// Copyright 2017 The NXT 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 "Utils.h"

#include "utils/NXTHelpers.h"

#include <vector>

nxt::Device device;

nxt::Buffer vertexBuffer;
nxt::Buffer vertexBufferQuad;

nxt::Texture renderTarget;
nxt::TextureView renderTargetView;
nxt::Sampler samplerPost;

nxt::Queue queue;
nxt::Pipeline pipeline;
nxt::Pipeline pipelinePost;
nxt::BindGroup bindGroup;
nxt::RenderPass renderpass;
nxt::Framebuffer framebuffer;

void initBuffers() {
    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::CreateFrozenBufferFromData(device, vertexData, sizeof(vertexData), nxt::BufferUsageBit::Vertex);

    static const float vertexDataQuad[24] = {
        -1.0f, -1.0f, 0.0f, 1.0f,
        -1.0f, 1.0f, 0.0f, 1.0f,
        1.0f, -1.0f, 0.0f, 1.0f,
        -1.0f, 1.0f, 0.0f, 1.0f,
        1.0f, -1.0f, 0.0f, 1.0f,
        1.0f, 1.0f, 0.0f, 1.0f,
    };
    vertexBufferQuad = utils::CreateFrozenBufferFromData(device, vertexDataQuad, sizeof(vertexDataQuad), nxt::BufferUsageBit::Vertex);
}

void initTextures() {
    renderTarget = device.CreateTextureBuilder()
        .SetDimension(nxt::TextureDimension::e2D)
        .SetExtent(640, 480, 1)
        .SetFormat(nxt::TextureFormat::R8G8B8A8Unorm)
        .SetMipLevels(1)
        .SetAllowedUsage(nxt::TextureUsageBit::ColorAttachment | nxt::TextureUsageBit::Sampled)
        .SetInitialUsage(nxt::TextureUsageBit::ColorAttachment)
        .GetResult();
    renderTargetView = renderTarget.CreateTextureViewBuilder().GetResult();

    samplerPost = device.CreateSamplerBuilder()
        .SetFilterMode(nxt::FilterMode::Linear, nxt::FilterMode::Linear, nxt::FilterMode::Linear)
        .GetResult();
}

void initRenderPass() {
    renderpass = device.CreateRenderPassBuilder()
        .SetAttachmentCount(2)
        .AttachmentSetFormat(0, nxt::TextureFormat::R8G8B8A8Unorm)
        .AttachmentSetFormat(1, nxt::TextureFormat::R8G8B8A8Unorm)
        .SetSubpassCount(2)
        // subpass 0
        .SubpassSetColorAttachment(0, 0, 0) // -> render target
        // subpass 1
        .SubpassSetColorAttachment(1, 0, 1) // -> back buffer
        .GetResult();
    framebuffer = device.CreateFramebufferBuilder()
        .SetRenderPass(renderpass)
        // attachment 0 -> render target
        .SetAttachment(0, renderTargetView)
        // attachment 1 -> back buffer
        // (implicit) // TODO(kainino@chromium.org): use the texture provided by WSI
        .SetDimensions(640, 480)
        .GetResult();
}

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

    nxt::ShaderModule fsModule = utils::CreateShaderModule(device, nxt::ShaderStage::Fragment, R"(
        #version 450
        layout(location = 0) out vec4 fragColor;
        void main() {
            fragColor = vec4(1.0, 0.0, 0.0, 1.0);
        })"
    );

    auto inputState = device.CreateInputStateBuilder()
        .SetAttribute(0, 0, nxt::VertexFormat::FloatR32G32B32A32, 0)
        .SetInput(0, 4 * sizeof(float), nxt::InputStepMode::Vertex)
        .GetResult();

    pipeline = device.CreatePipelineBuilder()
        .SetSubpass(renderpass, 0)
        .SetStage(nxt::ShaderStage::Vertex, vsModule, "main")
        .SetStage(nxt::ShaderStage::Fragment, fsModule, "main")
        .SetInputState(inputState)
        .GetResult();
}

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

    nxt::ShaderModule fsModule = utils::CreateShaderModule(device, nxt::ShaderStage::Fragment, R"(
        #version 450
        layout(set = 0, binding = 0) uniform sampler samp;
        layout(set = 0, binding = 1) uniform texture2D tex;
        layout(location = 0) out vec4 fragColor;
        void main() {
            fragColor = texture(sampler2D(tex, samp), gl_FragCoord.xy / vec2(640.0, 480.0)) + vec4(0.0, 0.0, 0.5, 0.0);
        })"
    );

    auto inputState = device.CreateInputStateBuilder()
        .SetAttribute(0, 0, nxt::VertexFormat::FloatR32G32B32A32, 0)
        .SetInput(0, 4 * sizeof(float), nxt::InputStepMode::Vertex)
        .GetResult();

    nxt::BindGroupLayout bgl = device.CreateBindGroupLayoutBuilder()
        .SetBindingsType(nxt::ShaderStageBit::Fragment, nxt::BindingType::Sampler, 0, 1)
        .SetBindingsType(nxt::ShaderStageBit::Fragment, nxt::BindingType::SampledTexture, 1, 1)
        .GetResult();

    nxt::PipelineLayout pl = device.CreatePipelineLayoutBuilder()
        .SetBindGroupLayout(0, bgl)
        .GetResult();

    pipelinePost = device.CreatePipelineBuilder()
        .SetSubpass(renderpass, 1)
        .SetLayout(pl)
        .SetStage(nxt::ShaderStage::Vertex, vsModule, "main")
        .SetStage(nxt::ShaderStage::Fragment, fsModule, "main")
        .SetInputState(inputState)
        .GetResult();

    bindGroup = device.CreateBindGroupBuilder()
        .SetLayout(bgl)
        .SetUsage(nxt::BindGroupUsage::Frozen)
        .SetSamplers(0, 1, &samplerPost)
        .SetTextureViews(1, 1, &renderTargetView)
        .GetResult();
}

void init() {
    device = CreateCppNXTDevice();

    queue = device.CreateQueueBuilder().GetResult();

    initBuffers();
    initTextures();
    initRenderPass();
    initPipeline();
    initPipelinePost();
}

void frame() {
    static const uint32_t vertexBufferOffsets[1] = {0};
    nxt::CommandBuffer commands = device.CreateCommandBufferBuilder()
        .BeginRenderPass(renderpass, framebuffer)
            // renderTarget is not transitioned here because it's implicit in
            // BeginRenderPass or AdvanceSubpass.
            .SetPipeline(pipeline)
            .SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets)
            .DrawArrays(3, 1, 0, 0)
        .AdvanceSubpass()
            // renderTarget must be transitioned here because it's Sampled, not
            // ColorAttachment or InputAttachment.
            .TransitionTextureUsage(renderTarget, nxt::TextureUsageBit::Sampled)
            .SetPipeline(pipelinePost)
            .SetBindGroup(0, bindGroup)
            .SetVertexBuffers(0, 1, &vertexBufferQuad, vertexBufferOffsets)
            .DrawArrays(6, 1, 0, 0)
        .EndRenderPass()
        .GetResult();

    queue.Submit(1, &commands);
    DoSwapBuffers();
}

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

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

    // TODO release stuff
}