//
//  Created by Bradley Austin Davis on 2015/06/12
//  Copyright 2015 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
#pragma once

#include <QtGlobal>

#include <openvr.h>

#include <display-plugins/hmd/HmdDisplayPlugin.h>

const float TARGET_RATE_OpenVr = 90.0f;  // FIXME: get from sdk tracked device property? This number is vive-only.

namespace gl {
    class OffscreenContext;
}
class OpenVrSubmitThread;
class OffscreenGLCanvas;
static const size_t COMPOSITING_BUFFER_SIZE = 3;

struct CompositeInfo {
    using Queue = std::queue<CompositeInfo>;
    using Array = std::array<CompositeInfo, COMPOSITING_BUFFER_SIZE>;
    
    gpu::TexturePointer texture;
    uint32_t textureID { 0 };
    glm::mat4 pose;
    void* fence{ 0 };
};

class OpenVrDisplayPlugin : public HmdDisplayPlugin {
    using Parent = HmdDisplayPlugin;
public:
    bool isSupported() const override;
    const QString getName() const override { return NAME; }

    glm::mat4 getEyeProjection(Eye eye, const glm::mat4& baseProjection) const override;
    glm::mat4 getCullingProjection(const glm::mat4& baseProjection) const override;

    void init() override;

    float getTargetFrameRate() const override;
    bool hasAsyncReprojection() const override { return _asyncReprojectionActive; }

    void customizeContext() override;
    void uncustomizeContext() override;

    // Stereo specific methods
    void resetSensors() override;
    bool beginFrameRender(uint32_t frameIndex) override;
    void cycleDebugOutput() override { _lockCurrentTexture = !_lockCurrentTexture; }

    bool suppressKeyboard() override;
    void unsuppressKeyboard() override;
    bool isKeyboardVisible() override;

    // Possibly needs an additional thread for VR submission
    int getRequiredThreadCount() const override;

    QString getPreferredAudioInDevice() const override;
    QString getPreferredAudioOutDevice() const override;

protected:
    bool internalActivate() override;
    void internalDeactivate() override;
    void updatePresentPose() override;

    void compositeLayers() override;
    void hmdPresent() override;
    bool isHmdMounted() const override;
    void postPreview() override;

private:
    vr::IVRSystem* _system { nullptr };
    std::atomic<vr::EDeviceActivityLevel> _hmdActivityLevel { vr::k_EDeviceActivityLevel_Unknown };
    std::atomic<uint32_t> _keyboardSupressionCount{ 0 };
    static const char* NAME;

    vr::HmdMatrix34_t _lastGoodHMDPose;
    mat4 _sensorResetMat;
    bool _threadedSubmit { true };

    CompositeInfo::Array _compositeInfos;
    size_t _renderingIndex { 0 };
    std::shared_ptr<OpenVrSubmitThread> _submitThread;
    std::shared_ptr<gl::OffscreenContext> _submitCanvas;
    friend class OpenVrSubmitThread;

    bool _asyncReprojectionActive { false };
};