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

#pragma once

#include <memory>
#include <unordered_map>
#include <unordered_set>

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

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

namespace open3d {
namespace visualization {
namespace rendering {

class FilamentMaterialModifier;
class FilamentRenderToBuffer;
class FilamentResourceManager;
class FilamentScene;
class FilamentView;

class FilamentRenderer : public Renderer {
public:
    FilamentRenderer(filament::Engine& engine,
                     void* native_drawable,
                     FilamentResourceManager& resource_mgr);
    // This will create an offscreen renderer
    explicit FilamentRenderer(filament::Engine& engine,
                              int width,
                              int height,
                              FilamentResourceManager& resource_mgr);
    ~FilamentRenderer() override;

    SceneHandle CreateScene() override;
    Scene* GetScene(const SceneHandle& id) const override;
    void DestroyScene(const SceneHandle& id) override;

    virtual void SetClearColor(const Eigen::Vector4f& color) override;
    void UpdateSwapChain() override;
    void UpdateBitmapSwapChain(int width, int height) override;

    void BeginFrame() override;
    void Draw() override;
    void RequestReadPixels(int width,
                           int height,
                           std::function<void(std::shared_ptr<core::Tensor>)>
                                   callback) override;
    void EndFrame() override;

    void SetOnAfterDraw(std::function<void()> callback) override;

    MaterialHandle AddMaterial(const ResourceLoadRequest& request) override;
    MaterialInstanceHandle AddMaterialInstance(
            const MaterialHandle& material) override;
    MaterialModifier& ModifyMaterial(const MaterialHandle& id) override;
    MaterialModifier& ModifyMaterial(const MaterialInstanceHandle& id) override;
    void RemoveMaterialInstance(const MaterialInstanceHandle& id) override;

    TextureHandle AddTexture(const ResourceLoadRequest& request,
                             bool srgb = false) override;
    TextureHandle AddTexture(const std::shared_ptr<geometry::Image> image,
                             bool srgb = false) override;
    TextureHandle AddTexture(const t::geometry::Image& image,
                             bool srgb = false) override;
    bool UpdateTexture(TextureHandle texture,
                       const std::shared_ptr<geometry::Image> image,
                       bool srgb) override;
    bool UpdateTexture(TextureHandle texture,
                       const t::geometry::Image& image,
                       bool srgb) override;
    void RemoveTexture(const TextureHandle& id) override;

    IndirectLightHandle AddIndirectLight(
            const ResourceLoadRequest& request) override;
    void RemoveIndirectLight(const IndirectLightHandle& id) override;

    SkyboxHandle AddSkybox(const ResourceLoadRequest& request) override;
    void RemoveSkybox(const SkyboxHandle& id) override;

    std::shared_ptr<visualization::rendering::RenderToBuffer>
    CreateBufferRenderer() override;

    // Removes scene from scenes list and draws it last
    // WARNING: will destroy previous gui scene if there was any
    void ConvertToGuiScene(const SceneHandle& id);
    FilamentScene* GetGuiScene() const { return gui_scene_.get(); }

    filament::Renderer* GetNative() { return renderer_; }

private:
    friend class FilamentRenderToBuffer;

    filament::Engine& engine_;
    filament::Renderer* renderer_ = nullptr;
    filament::SwapChain* swap_chain_ = nullptr;
    filament::SwapChain* swap_chain_cached_ = nullptr;

    std::unordered_map<REHandle_abstract, std::unique_ptr<FilamentScene>>
            scenes_;
    std::unique_ptr<FilamentScene> gui_scene_;

    std::unique_ptr<FilamentMaterialModifier> materials_modifier_;
    FilamentResourceManager& resource_mgr_;

    std::unordered_set<std::shared_ptr<FilamentRenderToBuffer>>
            buffer_renderers_;

    bool frame_started_ = false;
    std::function<void()> on_after_draw_;
    bool needs_wait_after_draw_ = false;
};

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