/***************************************************************************
  qgs3dmapscene.h
  --------------------------------------
  Date                 : July 2017
  Copyright            : (C) 2017 by Martin Dobias
  Email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGS3DMAPSCENE_H
#define QGS3DMAPSCENE_H

#include "qgis_3d.h"

#include <Qt3DCore/QEntity>

#include "qgsrectangle.h"
#include "qgscameracontroller.h"

#ifndef SIP_RUN
namespace Qt3DRender
{
  class QRenderSettings;
  class QCamera;
}

namespace Qt3DLogic
{
  class QFrameAction;
}

namespace Qt3DExtras
{
  class QForwardRenderer;
  class QSkyboxEntity;
}
#endif


class Qgs3DAxis;
class QgsAbstract3DEngine;
class QgsAbstract3DRenderer;
class QgsMapLayer;
class Qgs3DMapSettings;
class QgsTerrainEntity;
class QgsChunkedEntity;
class QgsSkyboxEntity;
class QgsSkyboxSettings;
class Qgs3DMapExportSettings;
class QgsPostprocessingEntity;
class QgsChunkNode;
class QgsDoubleRange;
class Qgs3DMapSceneEntity;


/**
 * \ingroup 3d
 * \brief Entity that encapsulates our 3D scene - contains all other entities (such as terrain) as children.
 */
#ifndef SIP_RUN
class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
{
#else
class _3D_EXPORT Qgs3DMapScene : public QObject
{
#endif

    Q_OBJECT
  public:
    //! Constructs a 3D scene based on map settings and Qt 3D renderer configuration
    Qgs3DMapScene( Qgs3DMapSettings &map, QgsAbstract3DEngine *engine ) SIP_SKIP;

    //! Returns camera controller
    QgsCameraController *cameraController() const { return mCameraController; }

    /**
     * Returns terrain entity (may be temporarily NULLPTR)
     * \note Not available in Python bindings
     */
    QgsTerrainEntity *terrainEntity() SIP_SKIP { return mTerrain; }

    //! Resets camera view to show the whole scene (top view)
    void viewZoomFull();

    /**
     * Resets camera view to show the extent \a extent (top view)
     *
     * \since QGIS 3.26
     */
    void setViewFrom2DExtent( const QgsRectangle &extent );

    /**
     * Calculates the 2D extent viewed by the 3D camera as the vertices of the viewed trapezoid
     *
     * \since QGIS 3.26
     */
    QVector<QgsPointXY> viewFrustum2DExtent() const;

    //! Returns number of pending jobs of the terrain entity
    int terrainPendingJobsCount() const;

    /**
     * Returns number of pending jobs for all chunked entities
     * \since QGIS 3.12
     */
    int totalPendingJobsCount() const;

    //! Enumeration of possible states of the 3D scene
    enum SceneState
    {
      Ready,     //!< The scene is fully loaded/updated
      Updating,  //!< The scene is still being loaded/updated
    };

    //! Returns the current state of the scene
    SceneState sceneState() const { return mSceneState; }

    /**
     * Given screen error (in pixels) and distance from camera (in 3D world coordinates), this function
     * estimates the error in world space. Takes into account camera's field of view and the screen (3D view) size.
     */
    float worldSpaceError( float epsilon, float distance ) const;

    //! Exports the scene according to the scene export settings
    void exportScene( const Qgs3DMapExportSettings &exportSettings );

    /**
     * Returns the active chunk nodes of \a layer
     *
     * \since QGIS 3.18
     */
    QVector<const QgsChunkNode *> getLayerActiveChunkNodes( QgsMapLayer *layer ) SIP_SKIP;

    /**
     * Returns the layers that contain chunked entities
     *
     * \since QGIS 3.32
     */
    QList<QgsMapLayer *> layers() const SIP_SKIP { return mLayerEntities.keys(); }

    /**
     * Returns the entity belonging to \a layer
     *
     * \since QGIS 3.32
     */
    Qt3DCore::QEntity *layerEntity( QgsMapLayer *layer ) const SIP_SKIP { return mLayerEntities.value( layer ); }

    /**
     * Returns the scene extent in the map's CRS
     *
     * \since QGIS 3.20
     */
    QgsRectangle sceneExtent() const;

    /**
     * Returns the scene's elevation range
     * \note Only some layer types are considered by this method (eg terrain, point cloud and mesh layers)
     *
     * \since QGIS 3.30
     */
    QgsDoubleRange elevationRange() const;

    /**
     * Returns the 3D axis object
     *
     * \since QGIS 3.26
     */
    Qgs3DAxis *get3DAxis() const SIP_SKIP { return m3DAxis; }

    /**
     * Returns the abstract 3D engine
     *
     * \since QGIS 3.26
     */
    QgsAbstract3DEngine *engine() const SIP_SKIP { return mEngine; }

    /**
     * Returns the 3D map settings.
     *
     * \since QGIS 3.30
     */
    Qgs3DMapSettings *mapSettings() const { return &mMap; }

    /**
     * Returns whether updates of the 3D scene's entities are allowed.
     * Normally, scene updates are enabled. But for debugging purposes,
     * it may be useful to temporarily disable scene updates.
     *
     * \since QGIS 3.40
     */
    bool hasSceneUpdatesEnabled() const { return mSceneUpdatesEnabled; }

    /**
     * Sets whether updates of the 3D scene's entities are allowed.
     * Normally, scene updates are enabled. But for debugging purposes,
     * it may be useful to temporarily disable scene updates.
     *
     * \since QGIS 3.40
     */
    void setSceneUpdatesEnabled( bool enabled ) { mSceneUpdatesEnabled = enabled; }

    /**
     * Returns a map of 3D map scenes (by name) open in the QGIS application.
     *
     * \note Only available from the QGIS desktop application.
     * \deprecated QGIS 3.36. Use QgisAppInterface::mapCanvases3D() instead.
     * \since QGIS 3.30
     */
    Q_DECL_DEPRECATED static QMap< QString, Qgs3DMapScene * > openScenes() SIP_DEPRECATED;

    /**
     * Enables OpenGL clipping based on the planes equations defined in \a clipPlaneEquations.
     * The number of planes is equal to the size of \a clipPlaneEquations.
     * A plane equation contains 4 elements.
     * A simple way to define a clip plane equation is to define a normalized normal to
     * the plane and its distance from the origin of the scene.
     * In that case, the first 3 elements are the coordinates of the normal of the plane as ``(X, Y, Z)``.
     * They need to be normalized.
     * The last element is the distance of the plane from the origin of the scene.
     * In mathematical terms, a 3d plane can be defined with the equation ``ax+by+cz+d=0``
     * The normal is ``(a, b, c)`` with ``|a, b, c| = 1``
     * The distance is ``-d``.
     *
     * By default, OpenGL supports up to 8 additional clipping planes. If \a clipPlaneEquations
     * contains more than 8 planes, only the first 8 ones will be used.
     * If \a clipPlaneEquations is empty, the clipping is disabled.
     *
     * \see disableClipping()
     * \since QGIS 3.40
    */
    void enableClipping( const QList<QVector4D> &clipPlaneEquations );

    /**
     * Disables OpenGL clipping.
     *
     * \see enableClipping()
     * \since QGIS 3.40
     */
    void disableClipping();

#ifndef SIP_RUN
    //! Static function for returning open 3D map scenes
    static std::function< QMap< QString, Qgs3DMapScene * >() > sOpenScenesFunction;
#endif

  signals:
    //! Emitted when the current terrain entity is replaced by a new one
    void terrainEntityChanged();
    //! Emitted when the number of terrain's pending jobs changes
    void terrainPendingJobsCountChanged();

    /**
     * Emitted when the total number of pending jobs changes
     * \since QGIS 3.12
     */
    void totalPendingJobsCountChanged();
    //! Emitted when the scene's state has changed
    void sceneStateChanged();

    //! Emitted when the FPS count changes
    void fpsCountChanged( float fpsCount );
    //! Emitted when the FPS counter is activated or deactivated
    void fpsCounterEnabledChanged( bool fpsCounterEnabled );

    /**
     * Emitted when the viewed 2D extent seen by the 3D camera has changed
     *
     * \since QGIS 3.26
     */
    void viewed2DExtentFrom3DChanged( QVector<QgsPointXY> extent );

    /**
     *  Emitted when one of the entities reaches its GPU memory limit
     *  and it is not possible to lower the GPU memory use by unloading
     *  data that's not currently needed.
     */
    void gpuMemoryLimitReached();

  public slots:
    //! Updates the temporale entities
    void updateTemporal();

  private slots:
    void onCameraChanged();
    void onFrameTriggered( float dt );
    void createTerrain();
    void onLayerRenderer3DChanged();
    void onLayersChanged();
    void createTerrainDeferred();
    void onBackgroundColorChanged();
    void updateLights();
    void updateCameraLens();
    void onSkyboxSettingsChanged();
    void onShadowSettingsChanged();
    void onAmbientOcclusionSettingsChanged();
    void onEyeDomeShadingSettingsChanged();
    void onDebugShadowMapSettingsChanged();
    void onDebugDepthMapSettingsChanged();
    void onCameraMovementSpeedChanged();
    void onCameraNavigationModeChanged();
    void onDebugOverlayEnabledChanged();

    void on3DAxisSettingsChanged();

    bool updateCameraNearFarPlanes();

  private:
#ifdef SIP_RUN
    Qgs3DMapScene();
    Qgs3DMapScene( const Qgs3DMapScene &other );
#endif

    void addLayerEntity( QgsMapLayer *layer );
    void removeLayerEntity( QgsMapLayer *layer );
    void addCameraViewCenterEntity( Qt3DRender::QCamera *camera );
    void addCameraRotationCenterEntity( QgsCameraController *controller );
    void setSceneState( SceneState state );
    void updateSceneState();
    void updateScene( bool forceUpdate = false );
    void finalizeNewEntity( Qt3DCore::QEntity *newEntity );
    int maximumTextureSize() const;

    void handleClippingOnEntity( QEntity *entity ) const;
    void handleClippingOnAllEntities() const;

  private:

    Qgs3DMapSettings &mMap;
    QgsAbstract3DEngine *mEngine = nullptr;
    //! Provides a way to have a synchronous function executed each frame
    Qt3DLogic::QFrameAction *mFrameAction = nullptr;
    QgsCameraController *mCameraController = nullptr;
    QgsTerrainEntity *mTerrain = nullptr;
    QList<Qgs3DMapSceneEntity *> mSceneEntities;
    //! Entity that shows view center - useful for debugging camera issues
    Qt3DCore::QEntity *mEntityCameraViewCenter = nullptr;
    //! Keeps track of entities that belong to a particular layer
    QMap<QgsMapLayer *, Qt3DCore::QEntity *> mLayerEntities;
    bool mTerrainUpdateScheduled = false;
    SceneState mSceneState = Ready;
    //! List of lights in the scene
    QList<Qt3DCore::QEntity *> mLightEntities;
    QList<QgsMapLayer *> mModelVectorLayers;
    QgsSkyboxEntity *mSkybox = nullptr;
    //! Entity that shows rotation center = useful for debugging camera issues
    Qt3DCore::QEntity *mEntityRotationCenter = nullptr;

    //! 3d axis visualization
    Qgs3DAxis *m3DAxis = nullptr;

    bool mSceneUpdatesEnabled = true;

    QList<QVector4D> mClipPlanesEquations;

};
#endif // QGS3DMAPSCENE_H
