/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_VIEW
#define OSG_VIEW 1

#include <osg/Camera>
#include <osg/Light>
#include <osg/Stats>

#include <OpenThreads/Mutex>

namespace osg {

/** View - maintains a master camera view and a list of slave cameras that are relative to this master camera.
  * Note, if no slave cameras are attached to the view then the master camera does both the control and implementation of the rendering of the scene,
  * but if slave cameras are present then the master controls the view onto the scene, while the slaves implement the rendering of the scene.
*/
class OSG_EXPORT View : public virtual osg::Object
{
    public :

        View();

        View(const osg::View& view, const osg::CopyOp& copyop=CopyOp::SHALLOW_COPY);

        META_Object(osg,View);

        /** Take all the settings, Camera and Slaves from the passed in view, leaving it empty. */
        virtual void take(View& rhs);


        /** Set the Stats object used for collect various frame related timing and scene graph stats.*/
        void setStats(osg::Stats* stats) { _stats = stats; }

        /** Get the Viewers Stats object.*/
        osg::Stats* getStats() { return _stats.get(); }

        /** Get the Viewers Stats object.*/
        const osg::Stats* getStats() const { return _stats.get(); }


        /** Options for controlling the global lighting used for the view.*/
        enum LightingMode
        {
            NO_LIGHT,
            HEADLIGHT,
            SKY_LIGHT
        };

        /** Set the global lighting to use for this view.
          * Defaults to headlight. */
        void setLightingMode(LightingMode lightingMode);

        /** Get the global lighting used for this view.*/
        LightingMode getLightingMode() const { return _lightingMode; }

        /** Get the global light.*/
        void setLight(osg::Light* light) { _light = light; }

        /** Get the global lighting if assigned.*/
        osg::Light* getLight() { return _light.get(); }

        /** Get the const global lighting if assigned.*/
        const osg::Light* getLight() const { return _light.get(); }

        /** Set the master camera of the view. */
        void setCamera(osg::Camera* camera);

        /** Get the master camera of the view. */
        osg::Camera* getCamera() { return _camera.get(); }

        /** Get the const master camera of the view. */
        const osg::Camera* getCamera() const { return _camera.get(); }

        /** Set the frame stamp of the view. */
        void setFrameStamp(osg::FrameStamp* fs) { _frameStamp = fs; }

        /** Get the frame stamp of the view. */
        osg::FrameStamp* getFrameStamp() { return _frameStamp.get(); }

        /** Get the frame stamp of the view. */
        const osg::FrameStamp* getFrameStamp() const { return _frameStamp.get(); }


        /** Slave allows one to up a camera that follows the master with a local offset to the project and view matrices.*/
        struct OSG_EXPORT Slave
        {
            Slave(bool useMastersSceneData=true):
                _useMastersSceneData(useMastersSceneData) {}

            Slave(osg::Camera* camera, const osg::Matrixd& projectionOffset, const osg::Matrixd& viewOffset, bool useMastersSceneData=true):
                _camera(camera),
                _projectionOffset(projectionOffset),
                _viewOffset(viewOffset),
                _useMastersSceneData(useMastersSceneData) {}

            Slave(const Slave& rhs) :
                _camera(rhs._camera),
                _projectionOffset(rhs._projectionOffset),
                _viewOffset(rhs._viewOffset),
                _useMastersSceneData(rhs._useMastersSceneData),
                _updateSlaveCallback(rhs._updateSlaveCallback) {}

            virtual ~Slave() {}

            Slave& operator = (const Slave& rhs)
            {
                _camera = rhs._camera;
                _projectionOffset = rhs._projectionOffset;
                _viewOffset = rhs._viewOffset;
                _useMastersSceneData = rhs._useMastersSceneData;
                _updateSlaveCallback = rhs._updateSlaveCallback;
                return *this;
            }

            struct UpdateSlaveCallback : public virtual Referenced
            {
                virtual void updateSlave(osg::View& view, osg::View::Slave& slave) = 0;
            };

            void updateSlave(View& view)
            {
                if (_updateSlaveCallback.valid()) _updateSlaveCallback->updateSlave(view, *this);
                else updateSlaveImplementation(view);
            }

            virtual void updateSlaveImplementation(View& view);

            osg::ref_ptr<osg::Camera>           _camera;
            osg::Matrixd                        _projectionOffset;
            osg::Matrixd                        _viewOffset;
            bool                                _useMastersSceneData;
            osg::ref_ptr<UpdateSlaveCallback>   _updateSlaveCallback;
        };

        bool addSlave(osg::Camera* camera, bool useMastersSceneData=true) { return addSlave(camera, osg::Matrix::identity(), osg::Matrix::identity(), useMastersSceneData); }

        bool addSlave(osg::Camera* camera, const osg::Matrix& projectionOffset, const osg::Matrix& viewOffset, bool useMastersSceneData=true);

        bool removeSlave(unsigned int pos);

        unsigned int getNumSlaves() const { return static_cast<unsigned int>(_slaves.size()); }

        Slave& getSlave(unsigned int pos) { return _slaves[pos]; }
        const Slave& getSlave(unsigned int pos) const { return _slaves[pos]; }

        unsigned int findSlaveIndexForCamera(osg::Camera* camera) const;

        Slave * findSlaveForCamera(osg::Camera* camera);

        void updateSlaves();

    protected :

        virtual ~View();

        virtual osg::GraphicsOperation* createRenderer(osg::Camera*) { return 0; }

        osg::ref_ptr<osg::Stats>        _stats;

        LightingMode                    _lightingMode;
        osg::ref_ptr<osg::Light>        _light;

        osg::ref_ptr<osg::Camera>       _camera;

        typedef std::vector<Slave>      Slaves;
        Slaves                          _slaves;

        osg::ref_ptr<osg::FrameStamp>   _frameStamp;
};

}

#endif
