/**
 * Stone of Orthanc
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2019 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program 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 GNU
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#pragma once

#include "../Messages/IObservable.h"
#include "../Messages/IObserver.h"
#include "../Oracle/GetOrthancImageCommand.h"
#include "../Oracle/GetOrthancWebViewerJpegCommand.h"
#include "../Oracle/IOracle.h"
#include "../Oracle/OracleCommandExceptionMessage.h"
#include "../Oracle/OrthancRestApiCommand.h"

#include <Core/IDynamicObject.h>

#include <list>

namespace OrthancStone
{
  /**
     This class is supplied with Oracle commands and will schedule up to 
     simultaneousDownloads_ of them at the same time, then will schedule the 
     rest once slots become available. It is used, a.o., by the 
     OrtancMultiframeVolumeLoader class.
  */
  class LoaderStateMachine : public IObserver
  {
  protected:
    class State : public Orthanc::IDynamicObject
    {
    private:
      LoaderStateMachine&  that_;

    public:
      State(LoaderStateMachine& that) :
      that_(that)
      {
      }

      State(const State& currentState) :
      that_(currentState.that_)
      {
      }

      void Schedule(OracleCommandWithPayload* command) const
      {
        that_.Schedule(command);
      }

      template <typename T>
      T& GetLoader() const
      {
        return dynamic_cast<T&>(that_);
      }
      
      virtual void Handle(const OrthancRestApiCommand::SuccessMessage& message);
      
      virtual void Handle(const GetOrthancImageCommand::SuccessMessage& message);
      
      virtual void Handle(const GetOrthancWebViewerJpegCommand::SuccessMessage& message);
    };

    void Schedule(OracleCommandWithPayload* command);

    void Start();

  private:
    void Step();

    void Clear();

    void HandleExceptionMessage(const OracleCommandExceptionMessage& message);

    template <typename T>
    void HandleSuccessMessage(const T& message);

    typedef std::list<IOracleCommand*>  PendingCommands;

    IOracle&         oracle_;
    bool             active_;
    unsigned int     simultaneousDownloads_;
    PendingCommands  pendingCommands_;
    unsigned int     activeCommands_;

  public:
    LoaderStateMachine(IOracle& oracle,
                       IObservable& oracleObservable);

    virtual ~LoaderStateMachine()
    {
      Clear();
    }

    bool IsActive() const
    {
      return active_;
    }

    void SetSimultaneousDownloads(unsigned int count);  
  };
}