//
// Software License for AMDiS
//
// Copyright (c) 2010 Dresden University of Technology 
// All rights reserved.
// Authors: Simon Vey, Thomas Witkowski et al.
//
// This file is part of AMDiS
//
// See also license.opensource.txt in the distribution.


#include "AdaptInstationary.h"
#include "Parameters.h"
#include "Estimator.h"
#include "ProblemIterationInterface.h"
#include "ProblemTimeInterface.h"
#include "Serializer.h"

#if HAVE_PARALLEL_DOMAIN_AMDIS
#include "parallel/MeshDistributor.h"
#include <petsc.h>
#endif

namespace AMDiS {

  AdaptInstationary::AdaptInstationary(std::string name,
				       ProblemIterationInterface *problemStat,  
				       AdaptInfo *info,
				       ProblemTimeInterface *problemInstat,
				       AdaptInfo *initialInfo,
				       time_t initialTimestampSet)
    : AdaptBase(name, problemStat, info, problemInstat, initialInfo),
      breakWhenStable(0),
      dbgMode(false)
  {
    FUNCNAME("AdaptInstationary::AdaptInstationary()");

    MSG("You make use of the obsolete constructor AdaptInstationary::AdaptInstationary(...)!\n");
    MSG("Please use the constructor that uses references instead of pointers!\n");

    initConstructor(problemStat, info, initialInfo, initialTimestampSet);
 }


  AdaptInstationary::AdaptInstationary(std::string name,
				       ProblemIterationInterface &problemStat,  
				       AdaptInfo &info,
				       ProblemTimeInterface &problemInstat,
				       AdaptInfo &initialInfo,
				       time_t initialTimestampSet)
    : AdaptBase(name, &problemStat, &info, &problemInstat, &initialInfo),
      breakWhenStable(0),
      dbgMode(false)
  {
    FUNCNAME("AdaptInstationary::AdaptInstationary()");

    initConstructor(&problemStat, &info, &initialInfo, initialTimestampSet);
  }


  void AdaptInstationary::initConstructor(ProblemIterationInterface *problemStat,  
					  AdaptInfo *info,
					  AdaptInfo *initialInfo,
					  time_t initialTimestampSet)
  {
    initialize(name);

    fixedTimestep = (info->getMinTimestep() == info->getMaxTimestep());
 
    if (initialTimestampSet == 0)
      initialTimestamp = time(NULL);
    else
      initialTimestamp = initialTimestampSet;

    // Check if the problem should be deserialized because of the -rs parameter.
    std::string serializationFilename = "";
    Parameters::get("argv->rs", serializationFilename);

    if (serializationFilename.compare("")) {
      // The value of the -rs argument is ignored, because we want to use the 
      // serialization file mentioned in the used init file.
      MSG("Deserialization from file: %s\n", queueSerializationFilename.c_str());

      std::ifstream in(queueSerializationFilename.c_str());
      deserialize(in);
      in.close();

      info->setIsDeserialized(true);
      initialInfo->setIsDeserialized(true);
    } else {
      int readSerialization = 0;
      int readSerializationWithAdaptInfo = 0;

      Parameters::get((*problemStat).getName() + "->input->read serialization",
		      readSerialization);
      Parameters::get((*problemStat).getName() + "->input->serialization with adaptinfo",
		      readSerializationWithAdaptInfo);

      if (readSerialization && readSerializationWithAdaptInfo) {
	std::string serializationFilename = "";

	Parameters::get((*problemStat).getName() + "->input->serialization filename", 
			serializationFilename);
	TEST_EXIT(serializationFilename != "")("no serialization file\n");

	MSG("Deserialization with AdaptInfo from file: %s\n", serializationFilename.c_str());
	std::ifstream in(serializationFilename.c_str());
	deserialize(in);
	in.close();
      }
    }
  }


  void AdaptInstationary::explicitTimeStrategy()
  {
    FUNCNAME("AdaptInstationary::explicitTimeStrategy()");

    // estimate before first adaption
    if (adaptInfo->getTime() <= adaptInfo->getStartTime())
      problemIteration->oneIteration(adaptInfo, ESTIMATE);


    // increment time
    adaptInfo->setTime(adaptInfo->getTime() + adaptInfo->getTimestep());

    problemTime->setTime(adaptInfo);

    INFO(info, 6)("time = %e, timestep = %e\n",
		  adaptInfo->getTime(), adaptInfo->getTimestep());

    adaptInfo->setSpaceIteration(0);
  
    // do the iteration
    problemIteration->beginIteration(adaptInfo);
    problemIteration->oneIteration(adaptInfo, FULL_ITERATION);
    problemIteration->endIteration(adaptInfo);
    adaptInfo->setLastProcessedTimestep(adaptInfo->getTimestep()); 
  }


  void AdaptInstationary::implicitTimeStrategy()
  {
    FUNCNAME("AdaptInstationary::implicitTimeStrategy()");

    do {
      adaptInfo->setTime(adaptInfo->getTime() + adaptInfo->getTimestep());
      problemTime->setTime(adaptInfo);

      INFO(info,6)("time = %e, try timestep = %e\n",
		   adaptInfo->getTime(), adaptInfo->getTimestep());

      problemIteration->oneIteration(adaptInfo, NO_ADAPTION);

      adaptInfo->incTimestepIteration();

      if (!fixedTimestep && 
	  !adaptInfo->timeToleranceReached() &&
	  adaptInfo->getTimestepIteration() <= adaptInfo->getMaxTimestepIteration() &&
	  !(adaptInfo->getTimestep() <= adaptInfo->getMinTimestep())) {
  
	adaptInfo->setTime(adaptInfo->getTime() - adaptInfo->getTimestep());
	adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta1);
	continue;
      }


      adaptInfo->setSpaceIteration(0);


      // === Do only space iterations only if the maximum is higher than 0. === 

      if (adaptInfo->getMaxSpaceIteration() > 0) {
    
	// === Space iterations. ===
	do {
	  problemIteration->beginIteration(adaptInfo);
	  
	  if (problemIteration->oneIteration(adaptInfo, FULL_ITERATION)) {
	    if (!fixedTimestep && 
		!adaptInfo->timeToleranceReached() &&
		!(adaptInfo->getTimestep() <= adaptInfo->getMinTimestep())) {
	      adaptInfo->setTime(adaptInfo->getTime() - adaptInfo->getTimestep());
	      adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta2);
	      problemIteration->endIteration(adaptInfo);
	      adaptInfo->incSpaceIteration();
	      break;
	    }	
	  }

	  adaptInfo->incSpaceIteration();
	  problemIteration->endIteration(adaptInfo);
	  
	} while (!adaptInfo->spaceToleranceReached() && 
		 adaptInfo->getSpaceIteration() <= adaptInfo->getMaxSpaceIteration());

      } else {
	problemIteration->endIteration(adaptInfo);
      }


    } while(!adaptInfo->timeToleranceReached() &&
	    !(adaptInfo->getTimestep() <= adaptInfo->getMinTimestep()) && 
	    adaptInfo->getTimestepIteration() <= adaptInfo->getMaxTimestepIteration());  

    adaptInfo->setLastProcessedTimestep(adaptInfo->getTimestep()); 

    // After successful iteration/timestep the timestep will be changed according 
    // adaption rules for next timestep. 
    // First, check for increase of timestep
    if (!fixedTimestep && adaptInfo->timeErrorLow()) {
      adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta2);
      if (dbgMode) {
	// print information about timestep increase
      }
    } else {
      if (dbgMode) {
	std::cout << "=== ADAPT INFO DEBUG MODE ===\n";
	std::cout << " Do not increase timestep: \n";
	if (fixedTimestep)
	  std::cout << "   fixedTimestep = true\n";	
	if (!adaptInfo->timeErrorLow())
	  adaptInfo->printTimeErrorLowInfo();
      }
    }

    // Second, check for decrease of timestep
    if (!fixedTimestep &&
	!adaptInfo->timeToleranceReached() &&
	!(adaptInfo->getTimestep() <= adaptInfo->getMinTimestep()))
	adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta1);    
  }


  void AdaptInstationary::simpleAdaptiveTimeStrategy()
  {
    FUNCNAME("AdaptInstationary::simpleAdaptiveTimeStrategy()");

    // estimate before first adaption
    if (adaptInfo->getTime() <= adaptInfo->getStartTime())
      problemIteration->oneIteration(adaptInfo, ESTIMATE);

    adaptInfo->setTime(adaptInfo->getTime() + adaptInfo->getTimestep());
    problemTime->setTime(adaptInfo);
    
    INFO(info,6)("time = %e, timestep = %e\n",
		 adaptInfo->getTime(), adaptInfo->getTimestep());
    
    problemIteration->oneIteration(adaptInfo, FULL_ITERATION);

    adaptInfo->setLastProcessedTimestep(adaptInfo->getTimestep());        

    if (dbgMode) {
	std::cout << "=== ADAPT INFO DEBUG MODE           ===\n";
	std::cout << "=== in simpleAdaptiveTimeStrategy() ===\n";
	adaptInfo->printTimeErrorLowInfo();
    }
    
    // First, check for increase of timestep
    if (!fixedTimestep && adaptInfo->timeErrorLow())
      adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta2);
    
    // Second, check for decrease of timestep
    if (!fixedTimestep &&
	!adaptInfo->timeToleranceReached() &&
	!(adaptInfo->getTimestep() <= adaptInfo->getMinTimestep()))
      adaptInfo->setTimestep(adaptInfo->getTimestep() * timeDelta1);    
  }


  void AdaptInstationary::oneTimestep()
  {
    FUNCNAME("AdaptInstationary::oneTimestep()");

    MSG("ONE TIMESTEP!\n");

    adaptInfo->setTimestepIteration(0);

    switch (strategy) {
    case 0:
      explicitTimeStrategy();
      break;
    case 1:
      implicitTimeStrategy();
      break;
    case 2:
      simpleAdaptiveTimeStrategy();
      break;
    default:
      ERROR_EXIT("Unknown strategy = %d!\n", strategy);
    }

    adaptInfo->incTimestepNumber();
  }


  int AdaptInstationary::adapt()
  {
    FUNCNAME("AdaptInstationary::adapt()");
    int errorCode = 0;

    TEST_EXIT(adaptInfo->getTimestep() >= adaptInfo->getMinTimestep())
      ("timestep < min timestep\n");
    TEST_EXIT(adaptInfo->getTimestep() <= adaptInfo->getMaxTimestep())
      ("timestep > max timestep\n");

    TEST_EXIT(adaptInfo->getTimestep() > 0)("timestep <= 0!\n");

#if HAVE_PARALLEL_DOMAIN_AMDIS
    MeshDistributor::globalMeshDistributor->initParallelization(); 
#endif

    if (adaptInfo->getTimestepNumber() == 0) {
      adaptInfo->setTime(adaptInfo->getStartTime());
      initialAdaptInfo->setStartTime(adaptInfo->getStartTime());
      initialAdaptInfo->setTime(adaptInfo->getStartTime());

      problemTime->setTime(adaptInfo);

      // initial adaption
      problemTime->solveInitialProblem(initialAdaptInfo);
      problemTime->transferInitialSolution(adaptInfo);
    }

    while (!adaptInfo->reachedEndTime()) {
      iterationTimestamp = time(NULL);

      problemTime->initTimestep(adaptInfo);
      oneTimestep();
      problemTime->closeTimestep(adaptInfo);

      if (breakWhenStable && (adaptInfo->getSolverIterations() == 0)) 
	break;

      // Check if there is a runtime limitation. If there is a runtime limitation
      // and there is no more time for a next adaption loop, than return the error
      // code for rescheduling the problem and break the adaption loop.
      if (checkQueueRuntime()) {
	errorCode = RescheduleErrorCode;
	break;
      }
    }

#ifdef HAVE_PARALLEL_DOMAIN_AMDIS
    MeshDistributor::globalMeshDistributor->exitParallelization();
    PetscFinalize();
#endif

    return errorCode;
  }


  void AdaptInstationary::initialize(std::string aName)
  {
    FUNCNAME("AdaptInstationary::initialize()");

    strategy = 0;
    timeDelta1 = 0.7071;
    timeDelta2 = 1.4142;
    queueRuntime = -1;
    queueSerializationFilename = "__serialized_problem.ser";

    Parameters::get(aName + "->strategy", strategy);
    Parameters::get(aName + "->time delta 1", timeDelta1);
    Parameters::get(aName + "->time delta 2", timeDelta2);
    Parameters::get(aName + "->info", info);
    Parameters::get(aName + "->break when stable", breakWhenStable);
    Parameters::get(aName + "->time adaptivity debug mode", dbgMode);
    Parameters::get(aName + "->queue->runtime", queueRuntime);
    Parameters::get(aName + "->queue->serialization filename", 
		    queueSerializationFilename);
  }


  void AdaptInstationary::serialize(std::ostream &out)
  {
    FUNCNAME("AdaptInstationary::serialize()");

    SerUtil::serialize(out, amdisRevisionNumber);
    problemIteration->serialize(out);
    adaptInfo->serialize(out);
    if (problemTime)
      problemTime->serialize(out);    
  }


  void AdaptInstationary::deserialize(std::istream &in)
  {
    FUNCNAME("AdaptInstationary::deserialize()");

    problemIteration->deserialize(in);
    adaptInfo->deserialize(in);
    if (problemTime)
      problemTime->deserialize(in);    
  }


  bool AdaptInstationary::checkQueueRuntime()
  {
    // If there is no time limited runtime queue, there is also nothing to check.
    if (queueRuntime == -1) {
      return false;
    }
    // Get the current time.
    time_t currentTimestamp = time(NULL);

    // Update list with the last iteration runtimes.
    lastIterationsDuration.push(currentTimestamp - iterationTimestamp);
    // The list should not contain more than 5 elements. If so, delete the oldest one.
    if (lastIterationsDuration.size() > 5)
      lastIterationsDuration.pop();    

    // Calculate the avarage of the last iterations.
    std::queue<int> tmpQueue = lastIterationsDuration;
    int avrgLastIterations = 0;
    while (!tmpQueue.empty()) {
	avrgLastIterations += tmpQueue.front();
	tmpQueue.pop();
    } 
    avrgLastIterations /= lastIterationsDuration.size();

    // Check if there is enough time for a further iteration.
    if (initialTimestamp + queueRuntime - currentTimestamp < avrgLastIterations * 2) {
      std::ofstream out(queueSerializationFilename.c_str());
      serialize(out);
      out.close();

      return true;
    }

    return false;
  }

}