/* -*-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_OPERATIONTHREAD
#define OSG_OPERATIONTHREAD 1

#include <osg/observer_ptr>
#include <osg/Object>

#include <OpenThreads/Thread>
#include <OpenThreads/Barrier>
#include <OpenThreads/Condition>
#include <OpenThreads/Block>

#include <list>
#include <set>

namespace osg {

class RefBlock : virtual public osg::Referenced, public OpenThreads::Block
{
    public:

        RefBlock():
            osg::Referenced(true) {}

};

class RefBlockCount : virtual public osg::Referenced, public OpenThreads::BlockCount
{
    public:

        RefBlockCount(unsigned blockCount):
            osg::Referenced(true),
            OpenThreads::BlockCount(blockCount) {}

};

/** Base class for implementing graphics operations.*/
class Operation : virtual public Referenced
{
    public:

        Operation(const std::string& name, bool keep):
            osg::Referenced(true),
            _name(name),
            _keep(keep) {}


        /** Set the human readable name of the operation.*/
        void setName(const std::string& name) { _name = name; }

        /** Get the human readable name of the operation.*/
        const std::string& getName() const { return _name; }

        /** Set whether the operation should be kept once its been applied.*/ 
        void setKeep(bool keep) { _keep = keep; }

        /** Get whether the operation should be kept once its been applied.*/ 
        bool getKeep() const { return _keep; }

        /** if this operation is a barrier then release it.*/
        virtual void release() {}

        /** Do the actual task of this operation.*/ 
        virtual void operator () (Object*) = 0;

    protected:
    
        Operation():
            Referenced(true),
            _keep(false) {}

        Operation(const Operation& op):
            Referenced(true),
            _name(op._name),
            _keep(op._keep) {}

        virtual ~Operation() {}

        std::string _name;
        bool        _keep;
};

class OperationThread;

class OSG_EXPORT OperationQueue : public Referenced
{
    public:
    
        OperationQueue();
        
        /** Get the next operation from the operation queue. 
          * Return null ref_ptr<> if no operations are left in queue. */  
        osg::ref_ptr<Operation> getNextOperation(bool blockIfEmpty = false);

        /** Return true if the operation queue is empty. */
        bool empty() const { return _operations.empty(); }
        
        /** Return the num of pending operations that are sitting in the OperationQueue.*/
        unsigned int getNumOperationsInQueue() const { return static_cast<unsigned int>(_operations.size()); }

        /** Add operation to end of OperationQueue, this will be 
          * executed by the operation thread once this operation gets to the head of the queue.*/
        void add(Operation* operation);
        
        /** Remove operation from OperationQueue.*/
        void remove(Operation* operation);

        /** Remove named operation from OperationQueue.*/
        void remove(const std::string& name);

        /** Remove all operations from OperationQueue.*/
        void removeAllOperations();
        
        /** Run the operations. */
        void runOperations(Object* callingObject=0);

        /** Call release on all operations. */
        void releaseAllOperations(); 

        /** Release operations block that is used to block threads that are waiting on an empty operations queue.*/
        void releaseOperationsBlock();

        typedef std::set<OperationThread*> OperationThreads;
        
        /** Get the set of OperationThreads that are sharing this OperationQueue. */
        const OperationThreads& getOperationThreads() const { return _operationThreads; }

    protected:

        virtual ~OperationQueue();

        friend class OperationThread;
        
        void addOperationThread(OperationThread* thread);
        void removeOperationThread(OperationThread* thread);
        
        typedef std::list< osg::ref_ptr<Operation> > Operations;

        OpenThreads::Mutex          _operationsMutex;
        osg::ref_ptr<osg::RefBlock> _operationsBlock;
        Operations                  _operations;
        Operations::iterator        _currentOperationIterator;

        OperationThreads            _operationThreads;
};

/** OperationThread is a helper class for running Operation within a single thread.*/
class OSG_EXPORT OperationThread : public Referenced, public OpenThreads::Thread
{
    public:
        OperationThread();

        void setParent(Object* parent) { _parent = parent; }

        Object* getParent() { return _parent.get(); }
        
        const Object* getParent() const { return _parent.get(); }


        /** Set the OperationQueue. */
        void setOperationQueue(OperationQueue* opq);

        /** Get the OperationQueue. */
        OperationQueue* getOperationQueue() { return _operationQueue.get(); }

        /** Get the const OperationQueue. */
        const OperationQueue* getOperationQueue() const { return _operationQueue.get(); }

        
        /** Add operation to end of OperationQueue, this will be 
          * executed by the graphics thread once this operation gets to the head of the queue.*/
        void add(Operation* operation);
        
        /** Remove operation from OperationQueue.*/
        void remove(Operation* operation);

        /** Remove named operation from OperationQueue.*/
        void remove(const std::string& name);

        /** Remove all operations from OperationQueue.*/
        void removeAllOperations();

        
        /** Get the operation currently being run.*/
        osg::ref_ptr<Operation> getCurrentOperation() { return _currentOperation; }

        /** Run does the opertion thread run loop.*/
        virtual void run();
        
        void setDone(bool done);
        
        bool getDone() const { return _done; }

        /** Cancel this graphics thread.*/        
        virtual int cancel();

    protected:
    
        virtual ~OperationThread();
        
        observer_ptr<Object>            _parent;

        bool                            _done;

        OpenThreads::Mutex              _threadMutex;
        osg::ref_ptr<OperationQueue>    _operationQueue;
        osg::ref_ptr<Operation>         _currentOperation;

};

typedef OperationThread OperationsThread;

}

#endif