/*
  JOB-TICKET.hpp  -  execution plan for render jobs

  Copyright (C)         Lumiera.org
    2012,               Hermann Vosseler <Ichthyostega@web.de>

  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.

  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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/


#ifndef PROC_ENGINE_JOB_TICKET_H
#define PROC_ENGINE_JOB_TICKET_H

#include "proc/common.hpp"
//#include "proc/state.hpp"
#include "proc/engine/job.hpp"
#include "proc/engine/frame-coord.hpp"
//#include "lib/time/timevalue.hpp"
//#include "lib/time/timequant.hpp"
#include "lib/linked-elements.hpp"
#include "lib/iter-adapter.hpp"

#include <boost/noncopyable.hpp>
#include <stack>


namespace proc {
namespace engine {
  
//using lib::time::TimeSpan;
//using lib::time::Duration;
//using lib::time::FSecs;
//using lib::time::Time;
using lib::LinkedElements;
//  
//class ExitNode;
  
  /** 
   * a job closure represents the execution context of a job.
   * This allows us to enqueue simple job-"functions" with the scheduler.
   * By virtue of the JobClosure-pointer, embedded into #lumiera_jobDefinition,
   * the invocation of such a job may re-gain the full context, including the
   * actual ProcNode to pull and further specifics, like the media channel.
   */ 
  class JobClosure
    : public lumiera_jobClosure
    {
    public:
      virtual ~JobClosure();     ///< this is an interface
      
      
      virtual void invokeJobOperation (JobParameter parameter)  =0;
      virtual void signalFailure      (JobParameter parameter)  =0;
      
      virtual JobKind getJobKind()  const                       =0;
      virtual bool verify (Time nominalJobTime)  const          =0;
    };
  
  
  
  /**
   * execution plan for pulling a specific exit node.
   * Usable as blue print for generating actual render jobs.
   * Job tickets are created on demand, specialised for each segment
   * of the low-level model, and for each individual feed (corresponding
   * to a single model port). Once created, they are final for this segment,
   * stored together with the other descriptor objects (ProcNode and WiringDescriptor)
   * and finally discarded in bulk, in case that segment of the low-level model becomes
   * obsolete and is replaced by a newly built new version of this model segment.
   * 
   * Job tickets are created by a classical recursive descent call on the exit node,
   * which figures out everything to be done for generating data from this node.
   * To turn a JobTicket into an actual job, we need the additional information
   * regarding the precise frame number (=nominal time) and the channel number
   * to calculate (in case the actual feed is multichannel, which is the default).
   * This way, the JobTicket acts as <i>higher order function:</i> a function
   * generating on invocation another, specific function (= the job).
   * 
   * @todo 1/12 WIP-WIP-WIP defining the invocation sequence and render jobs
   */
  class JobTicket
    : boost::noncopyable
    {
      struct Provision
        {
          Provision* next;
        };
      
      struct Prerequisite
        {
          Prerequisite* next;
          JobTicket* descriptor;
        };
      
      struct Prerequisites ///< per channel
        {
          Prerequisites* next;
          LinkedElements<Prerequisite> requiredJobs_;
        };
      
      
      
      LinkedElements<Provision>   channelConfig_;
      LinkedElements<Prerequisites> requirement_;
      
      
      class ExplorationState;
      friend class ExplorationState;
      
      struct TraversalOfPrerequisites;
        
    public:
        
      typedef TraversalOfPrerequisites iterator;
      
      
      JobTicket()
        {
          UNIMPLEMENTED ("job representation, planning and scheduling");
        }
      
      
      iterator discoverPrerequisites()  const;
      
      Job createJobFor (FrameCoord coordinates);
      
      
      bool
      isValid()  const
        {
          UNIMPLEMENTED ("validity self check");
        }
    };
  
  
  class JobTicket::ExplorationState
    {
      typedef LinkedElements<Prerequisite>::iterator SubTicketSeq;
      typedef std::stack<SubTicketSeq> SubTicketStack;               //////////////////////////TODO use a custom container to avoid heap allocations
      
      SubTicketStack toExplore_;
      
    public:
      // using default ctor and copy operations
      
      
      
      /* === Iteration control API for IterStateWrapper== */
  
      friend bool
      checkPoint (ExplorationState const& plan)
      {
        UNIMPLEMENTED ("detect end of prerequisites");
      }
      
      friend JobTicket&
      yield (ExplorationState const& plan)
      {
        UNIMPLEMENTED ("access prerequisite and follow up to prerequisite JobTicket");
      }
      
      friend void
      iterNext (ExplorationState & plan)
      {
        UNIMPLEMENTED ("step ahead to next prerequisite");
      }      
    };
    
  
  struct JobTicket::TraversalOfPrerequisites
    : lib::IterStateWrapper<JobTicket, JobTicket::ExplorationState>
    {
      void
      push (TraversalOfPrerequisites subExploration)
        {
          UNIMPLEMENTED ("integrate a branch of prerequisites");
        }
      
    };
  
  
  inline JobTicket::iterator
  JobTicket::discoverPrerequisites()  const
  {
    UNIMPLEMENTED("delve into the requirement_ datastructure");
  }

  
  
  
}} // namespace proc::engine
#endif