// src/backend/policies_gatekeeper.cc - Copyright 2005, 2006, University
//               of Padova, dept. of Pure and Applied
//               Mathematics
//
// This file is part of SGPEMv2.
//
// This 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.
//
// SGPEMv2 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 SGPEMv2; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

#include "config.h"

#include "policies_gatekeeper.hh"
#include "policy_manager.hh"
#include "policy.hh"

// Include full template definition only in implementation files:
#include "singleton.tcc"

#include <algorithm>
#include <cassert>

using std::vector;
using std::map;
using std::find;
using std::runtime_error;
using namespace sgpem;

// Explicit template instantiation to allow to export symbols from the DSO.
template class SG_DLLEXPORT Singleton<PoliciesGatekeeper>;

typedef vector<PolicyManager*>::iterator ManagerIterator;
typedef map<History*, Policy*>::iterator ActiveIterator;

vector<PolicyManager*>
PoliciesGatekeeper::get_registered() const
{
  return _registered;
}

void
PoliciesGatekeeper::register_manager(PolicyManager* manager)
{
  assert(manager != NULL);

  ManagerIterator end = _registered.end();

  if(find(_registered.begin(), end, manager) == end)
    _registered.push_back(manager);
}

void
PoliciesGatekeeper::unregister_manager(PolicyManager* manager)
{
  assert(manager != NULL);

  ManagerIterator end = _registered.end();
  ManagerIterator pos = find(_registered.begin(), end, manager);

  if(pos != end)
  {
    deactivate_policies(*pos);
    _registered.erase(pos);
  }
}

Policy*
PoliciesGatekeeper::get_current_policy(History* history) throw(runtime_error)
{
  assert(history != NULL);

  ActiveIterator policy = _active_policies.find(history);

  if(policy == _active_policies.end())
    throw runtime_error("No active policy associated with this "
                        "history is available.");

  return policy->second;
}

void
PoliciesGatekeeper::activate_policy(History *history, Policy* policy)
{
  assert(history != NULL && policy != NULL);

  ActiveIterator end = _active_policies.end();
  ActiveIterator pos = _active_policies.find(history);

  if(pos != end && pos->second != policy)
    _active_policies[history]->deactivate();

  if(pos == end || pos->second != policy)
  {
    _active_policies[history] = policy;
    _active_policies[history]->activate();
  }
}

PoliciesGatekeeper::PoliciesGatekeeper()
{}

void
PoliciesGatekeeper::deactivate_policies(PolicyManager* manager)
{
  typedef vector<Policy*>::iterator PolicyIterator;

  vector<Policy*> avail_policies = manager->get_avail_policies();

  PolicyIterator avail_it = avail_policies.begin();
  PolicyIterator avail_end = avail_policies.end();

  for(; avail_it != avail_end; ++avail_it)
  {
    // TODO isn't there a way to write more compact code by using
    // library utilities?
    ActiveIterator act_it = _active_policies.begin();

    for(; act_it != _active_policies.end(); ++act_it)
    {
      if(act_it->second == *avail_it)
      {
        act_it->second->deactivate();
        _active_policies.erase(act_it);
      }
    }
  }
}