// Written by David Megginson, started 2000-12
//
// Copyright (C) 2000  David Megginson, david@megginson.com
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$

#ifdef HAVE_CONFIG_H
#  include <simgear_config.h>
#endif

#include <simgear/debug/logstream.hxx>
#include <simgear/timing/timestamp.hxx>

#include "exception.hxx"
#include "subsystem_mgr.hxx"

#include <simgear/math/SGMath.hxx>
#include "SGSmplstat.hxx"

const int SG_MAX_SUBSYSTEM_EXCEPTIONS = 4;

using std::string;

////////////////////////////////////////////////////////////////////////
// Implementation of SGSubsystem
////////////////////////////////////////////////////////////////////////

SGSubsystemTimingCb SGSubsystem::reportTimingCb = NULL;
void* SGSubsystem::reportTimingUserData = NULL;

SGSubsystem::SGSubsystem ()
  : _suspended(false)
{
}

SGSubsystem::~SGSubsystem ()
{
}

void
SGSubsystem::init ()
{
}

SGSubsystem::InitStatus
SGSubsystem::incrementalInit ()
{
  init();
  return INIT_DONE;
}

void
SGSubsystem::postinit ()
{
}

void
SGSubsystem::reinit ()
{
}

void
SGSubsystem::shutdown ()
{
}

void
SGSubsystem::bind ()
{
}

void
SGSubsystem::unbind ()
{
}

void
SGSubsystem::suspend ()
{
  _suspended = true;
}

void
SGSubsystem::suspend (bool suspended)
{
  _suspended = suspended;
}

void
SGSubsystem::resume ()
{
  _suspended = false;
}

bool
SGSubsystem::is_suspended () const
{
  return _suspended;
}

void SGSubsystem::stamp(const string& name)
{
    timingInfo.push_back(TimingInfo(name, SGTimeStamp::now()));
}

////////////////////////////////////////////////////////////////////////
// Implementation of SGSubsystemGroup.
////////////////////////////////////////////////////////////////////////

class SGSubsystemGroup::Member
{    
private:
    Member (const Member &member);
public:
    Member ();
    virtual ~Member ();
    
    virtual void update (double delta_time_sec);

    void reportTiming(void) { if (reportTimingCb) reportTimingCb(reportTimingUserData, name, &timeStat); }
    void updateExecutionTime(double time) { timeStat += time;}

    SampleStatistic timeStat;
    std::string name;
    SGSharedPtr<SGSubsystem> subsystem;
    double min_step_sec;
    double elapsed_sec;
    bool collectTimeStats;
    int exceptionCount;
    int initTime;
};



SGSubsystemGroup::SGSubsystemGroup () :
  _fixedUpdateTime(-1.0),
  _updateTimeRemainder(0.0),
  _initPosition(0)
{
}

SGSubsystemGroup::~SGSubsystemGroup ()
{
    // reverse order to prevent order dependency problems
    for( size_t i = _members.size(); i > 0; i-- )
    {
        delete _members[i-1];
    }
}

void
SGSubsystemGroup::init ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->init();
}

SGSubsystem::InitStatus
SGSubsystemGroup::incrementalInit()
{
  if (_initPosition >= _members.size())
    return INIT_DONE;
  
  SGTimeStamp st;
  st.stamp();
  InitStatus memberStatus = _members[_initPosition]->subsystem->incrementalInit();
  _members[_initPosition]->initTime += st.elapsedMSec();
  
  if (memberStatus == INIT_DONE)
    ++_initPosition;
  
  return INIT_CONTINUE;
}

void
SGSubsystemGroup::postinit ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->postinit();
}

void
SGSubsystemGroup::reinit ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->reinit();
}

void
SGSubsystemGroup::shutdown ()
{
    // reverse order to prevent order dependency problems
    for( size_t i = _members.size(); i > 0; i-- )
        _members[i-1]->subsystem->shutdown();
  _initPosition = 0;
}

void
SGSubsystemGroup::bind ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->bind();
}

void
SGSubsystemGroup::unbind ()
{
    // reverse order to prevent order dependency problems
    for( size_t i = _members.size(); i > 0; i-- )
       _members[i-1]->subsystem->unbind();
}

void
SGSubsystemGroup::update (double delta_time_sec)
{
    int loopCount = 1;
    // if dt == 0.0, we are paused, so we need to run one iteration
    // of our members; if we have a fixed update time, we compute a
    // loop count, and locally adjust dt
    if ((delta_time_sec > 0.0) && (_fixedUpdateTime > 0.0)) {
      double localDelta = delta_time_sec + _updateTimeRemainder;
      loopCount = SGMiscd::roundToInt(localDelta / _fixedUpdateTime);
      _updateTimeRemainder = delta_time_sec - (loopCount * _fixedUpdateTime);
      delta_time_sec = _fixedUpdateTime;
    }

    bool recordTime = (reportTimingCb != NULL);
    SGTimeStamp timeStamp;
    while (loopCount-- > 0) {
      for( size_t i = 0; i < _members.size(); i++ )
      {
          if (recordTime)
              timeStamp = SGTimeStamp::now();

          _members[i]->update(delta_time_sec); // indirect call

          if ((recordTime)&&(reportTimingCb))
          {
              timeStamp = SGTimeStamp::now() - timeStamp;
              _members[i]->updateExecutionTime(timeStamp.toUSecs());
          }
      }
    } // of multiple update loop
}

void
SGSubsystemGroup::reportTiming(void)
{
    for( size_t i = _members.size(); i > 0; i-- )
    {
        _members[i-1]->reportTiming();
    }
}

void
SGSubsystemGroup::suspend ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->suspend();
}

void
SGSubsystemGroup::resume ()
{
    for( size_t i = 0; i < _members.size(); i++ )
        _members[i]->subsystem->resume();
}

string_list
SGSubsystemGroup::member_names() const
{
	string_list result;
	for( size_t i = 0; i < _members.size(); i++ )
		result.push_back( _members[i]->name );
	
	return result;
}

bool
SGSubsystemGroup::is_suspended () const
{
    return false;
}

void
SGSubsystemGroup::set_subsystem (const string &name, SGSubsystem * subsystem,
                                 double min_step_sec)
{
    Member * member = get_member(name, true);
    if (member->subsystem != 0)
        delete member->subsystem;
    member->name = name;
    member->subsystem = subsystem;
    member->min_step_sec = min_step_sec;
}

SGSubsystem *
SGSubsystemGroup::get_subsystem (const string &name)
{
    Member * member = get_member(name);
    if (member != 0)
        return member->subsystem;
    else
        return 0;
}

void
SGSubsystemGroup::remove_subsystem (const string &name)
{
    MemberVec::iterator it = _members.begin();
    for (; it != _members.end(); ++it) {
        if (name == (*it)->name) {
            delete *it;
            _members.erase(it);
            return;
        }
    }
    
    SG_LOG(SG_GENERAL, SG_WARN, "remove_subsystem: missing:" << name);
}

//------------------------------------------------------------------------------
void SGSubsystemGroup::clearSubsystems()
{
  for( MemberVec::iterator it = _members.begin();
                           it != _members.end();
                         ++it )
    delete *it;
  _members.clear();
}

void
SGSubsystemGroup::set_fixed_update_time(double dt)
{
  _fixedUpdateTime = dt;
}

bool
SGSubsystemGroup::has_subsystem (const string &name) const
{
    return (((SGSubsystemGroup *)this)->get_member(name) != 0);
}

SGSubsystemGroup::Member *
SGSubsystemGroup::get_member (const string &name, bool create)
{
    for( size_t i = 0; i < _members.size(); i++ ) {
        if (_members[i]->name == name)
            return _members[i];
    }
    if (create) {
        Member * member = new Member;
        _members.push_back(member);
        return member;
    } else {
        return 0;
    }
}


////////////////////////////////////////////////////////////////////////
// Implementation of SGSubsystemGroup::Member
////////////////////////////////////////////////////////////////////////


SGSubsystemGroup::Member::Member ()
    : name(""),
      subsystem(0),
      min_step_sec(0),
      elapsed_sec(0),
      exceptionCount(0),
      initTime(0)
{
}

// This shouldn't be called due to subsystem pointer ownership issues.
SGSubsystemGroup::Member::Member (const Member &)
{
}

SGSubsystemGroup::Member::~Member ()
{
}

void
SGSubsystemGroup::Member::update (double delta_time_sec)
{
    elapsed_sec += delta_time_sec;
    if (elapsed_sec < min_step_sec) {
        return;
    }
    
    if (subsystem->is_suspended()) {
        return;
    }
    
    try {
      subsystem->update(elapsed_sec);
      elapsed_sec = 0;
    } catch (sg_exception& e) {
      SG_LOG(SG_GENERAL, SG_ALERT, "caught exception processing subsystem:" << name
        << "\nmessage:" << e.getMessage());
      
      if (++exceptionCount > SG_MAX_SUBSYSTEM_EXCEPTIONS) {
        SG_LOG(SG_GENERAL, SG_ALERT, "(exceptionCount=" << exceptionCount <<
          ", suspending)");
        subsystem->suspend();
      }
    }
}


////////////////////////////////////////////////////////////////////////
// Implementation of SGSubsystemMgr.
////////////////////////////////////////////////////////////////////////


SGSubsystemMgr::SGSubsystemMgr () :
  _initPosition(0)
{
  for (int i = 0; i < MAX_GROUPS; i++) {
    _groups[i] = new SGSubsystemGroup;
  }
}

SGSubsystemMgr::~SGSubsystemMgr ()
{
  // ensure get_subsystem returns NULL from now onwards,
  // before the SGSubsystemGroup destructors are run
  _subsystem_map.clear();
  
  for (int i = 0; i < MAX_GROUPS; i++) {
    delete _groups[i];
  }
}

void
SGSubsystemMgr::init ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
            _groups[i]->init();
}

SGSubsystem::InitStatus
SGSubsystemMgr::incrementalInit()
{
  if (_initPosition >= MAX_GROUPS)
    return INIT_DONE;
  
  InitStatus memberStatus = _groups[_initPosition]->incrementalInit();  
  if (memberStatus == INIT_DONE)
    ++_initPosition;
  
  return INIT_CONTINUE;
}

void
SGSubsystemMgr::postinit ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
            _groups[i]->postinit();
}

void
SGSubsystemMgr::reinit ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
            _groups[i]->reinit();
}

void
SGSubsystemMgr::shutdown ()
{
    // reverse order to prevent order dependency problems
    for (int i = MAX_GROUPS-1; i >= 0; i--)
        _groups[i]->shutdown();
  
    _initPosition = 0;
}


void
SGSubsystemMgr::bind ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
        _groups[i]->bind();
}

void
SGSubsystemMgr::unbind ()
{
    // reverse order to prevent order dependency problems
    for (int i = MAX_GROUPS-1; i >= 0; i--)
        _groups[i]->unbind();
}

void
SGSubsystemMgr::update (double delta_time_sec)
{
    for (int i = 0; i < MAX_GROUPS; i++) {
        _groups[i]->update(delta_time_sec);
    }
}

void
SGSubsystemMgr::suspend ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
        _groups[i]->suspend();
}

void
SGSubsystemMgr::resume ()
{
    for (int i = 0; i < MAX_GROUPS; i++)
        _groups[i]->resume();
}

bool
SGSubsystemMgr::is_suspended () const
{
    return false;
}

void
SGSubsystemMgr::add (const char * name, SGSubsystem * subsystem,
                     GroupType group, double min_time_sec)
{
    SG_LOG(SG_GENERAL, SG_DEBUG, "Adding subsystem " << name);
    get_group(group)->set_subsystem(name, subsystem, min_time_sec);

    if (_subsystem_map.find(name) != _subsystem_map.end()) {
        SG_LOG(SG_GENERAL, SG_ALERT, "Adding duplicate subsystem " << name);
        throw sg_exception("duplicate subsystem:" + std::string(name));
    }
    _subsystem_map[name] = subsystem;
}

void
SGSubsystemMgr::remove(const char* name)
{
  SubsystemDict::iterator s =_subsystem_map.find(name);
  if (s == _subsystem_map.end()) {
    return;
  }
  
  _subsystem_map.erase(s);
  
// tedious part - we don't know which group the subsystem belongs too
  for (int i = 0; i < MAX_GROUPS; i++) {
    if (_groups[i]->get_subsystem(name) != NULL) {
      _groups[i]->remove_subsystem(name);
      break;
    }
  } // of groups iteration
}


SGSubsystemGroup *
SGSubsystemMgr::get_group (GroupType group)
{
    return _groups[group];
}

SGSubsystem *
SGSubsystemMgr::get_subsystem (const string &name) const
{
    SubsystemDict::const_iterator s =_subsystem_map.find(name);

    if (s == _subsystem_map.end())
        return 0;
    else
        return s->second;
}

/** Trigger the timing callback to report data for all subsystems. */
void
SGSubsystemMgr::reportTiming()
{
    for (int i = 0; i < MAX_GROUPS; i++) {
        _groups[i]->reportTiming();
    } // of groups iteration
}

// end of subsystem_mgr.cxx