// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2023 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------

#pragma once

#include "open3d/visualization/rendering/RenderToBuffer.h"

/// @cond
namespace filament {
class Engine;
class Renderer;
class Scene;
class SwapChain;
}  // namespace filament
/// @endcond

namespace open3d {
namespace visualization {
namespace rendering {

class FilamentRenderer;
class FilamentScene;
class FilamentView;

class FilamentRenderToBuffer : public RenderToBuffer {
public:
    // Use Renderer::CreateBufferRenderer to instantiate
    // FilamentRenderToBuffer, unless you are NOT using
    // open3d::visualization::gui or another FilamentRenderer instance.
    explicit FilamentRenderToBuffer(filament::Engine& engine);
    ~FilamentRenderToBuffer() override;

    void Configure(const View* view,
                   Scene* scene,
                   int width,
                   int height,
                   int n_channels,
                   bool depth_image,
                   BufferReadyCallback cb) override;
    void SetDimensions(std::uint32_t width, std::uint32_t height) override;
    View& GetView() override;

    void Render() override;

    // Renders the minimum necessary to get Filament to tick its rendering
    // thread.
    void RenderTick();

private:
    friend class FilamentRenderer;

    filament::Engine& engine_;
    filament::Renderer* renderer_ = nullptr;
    filament::SwapChain* swapchain_ = nullptr;
    FilamentView* view_ = nullptr;
    FilamentScene* scene_ = nullptr;

    std::size_t width_ = 0;
    std::size_t height_ = 0;
    std::size_t n_channels_ = 0;
    std::uint8_t* buffer_ = nullptr;
    std::size_t buffer_size_ = 0;
    bool depth_image_ = false;

    BufferReadyCallback callback_;
    bool frame_done_ = true;
    bool pending_ = false;

    static void ReadPixelsCallback(void* buffer, size_t size, void* user);
    void CopySettings(const View* view);
};

}  // namespace rendering
}  // namespace visualization
}  // namespace open3d