/*
 * Project: MoleCuilder
 * Description: creates and alters molecular systems
 * Copyright (C)  2017 Frederik Heber. All rights reserved.
 *
 *
 *   This file is part of MoleCuilder.
 *
 *    MoleCuilder 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.
 *
 *    MoleCuilder 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 MoleCuilder.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * BondVectors.cpp
 *
 *  Created on: Jun 13, 2017
 *      Author: heber
 */


// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

//#include "CodePatterns/MemDebug.hpp"

#include "BondVectors.hpp"

#include <algorithm>
#include <functional>
#include <iterator>
#include <numeric>

#include "CodePatterns/Assert.hpp"
#include "CodePatterns/Log.hpp"

#include "Atom/atom.hpp"
#include "Bond/bond.hpp"
#include "Helpers/defs.hpp"

void BondVectors::recalculateBondVectorsAtStep(
    const size_t &_step) const
{
  current_mapped_vectors.clear();

  ASSERT( !container.empty(),
      "BondVectors::getBondVectors() - container empty, not set properly?");
  for (container_t::const_iterator iter = container.begin();
      iter != container.end(); ++iter) {
    const bond::ptr &current_bond = *iter;
    Vector BondVector = current_bond->leftatom->getPositionAtStep(_step)
        - current_bond->rightatom->getPositionAtStep(_step);
    BondVector.Normalize();
    current_mapped_vectors.insert( std::make_pair(current_bond, BondVector) );
  }
  ASSERT( current_mapped_vectors.size() == container.size(),
      "BondVectors::getBondVectors() - not same amount of bond vectors as bonds?");

  map_is_dirty = false;
  current_step_for_map = _step;
}

size_t BondVectors::getIndexForBond(const bond::ptr &_bond) const
{
  std::pair<
      container_t::const_iterator,
      container_t::const_iterator> iters =
          std::equal_range(container.begin(), container.end(), _bond);
  if (iters.first != container.end())
    return std::distance(container.begin(), iters.first);
  else
    return (size_t)-1;
}

std::vector<Vector> BondVectors::getAtomsBondVectorsAtStep(
    const atom &_walker,
    const size_t &_step) const
{
  if (map_is_dirty || (current_step_for_map != _step))
    recalculateBondVectorsAtStep(_step);

  std::vector<Vector> BondVectors;
  // gather subset of BondVectors for the current atom
  const BondList& ListOfBonds = _walker.getListOfBonds();
  for(BondList::const_iterator bonditer = ListOfBonds.begin();
      bonditer != ListOfBonds.end(); ++bonditer) {
    const bond::ptr &current_bond = *bonditer;
    const BondVectors::mapped_t::const_iterator bviter =
        current_mapped_vectors.find(current_bond);
    ASSERT( bviter != current_mapped_vectors.end(),
        "ForceAnnealing() - cannot find current_bond ?");
    ASSERT( bviter != current_mapped_vectors.end(),
        "ForceAnnealing - cannot find current bond "+toString(*current_bond)
        +" in bonds.");
    BondVectors.push_back(bviter->second);
  }
  LOG(4, "DEBUG: BondVectors for atom #" << _walker.getId() << ": " << BondVectors);

  return BondVectors;
}

BondVectors::weights_t BondVectors::getWeightsForAtomAtStep(
    const atom &_walker,
    const size_t &_step) const
{
  const std::vector<Vector> BondVectors =
      getAtomsBondVectorsAtStep(_walker, _step);

  weights_t weights;
  for (std::vector<Vector>::const_iterator iter = BondVectors.begin();
      iter != BondVectors.end(); ++iter) {
    std::vector<double> scps;
    scps.reserve(BondVectors.size());
    std::transform(
        BondVectors.begin(), BondVectors.end(),
        std::back_inserter(scps),
        boost::bind(static_cast< double (*)(double) >(&fabs),
            boost::bind(&Vector::ScalarProduct, boost::cref(*iter), _1))
        );
    const double scp_sum = std::accumulate(scps.begin(), scps.end(), 0.);
    ASSERT( (scp_sum-1.) > -MYEPSILON,
        "ForceAnnealing() - sum of weights must be equal or larger one but is "
        +toString(scp_sum));
    weights.push_back( 1./scp_sum );
  }
  LOG(4, "DEBUG: Weights for atom #" << _walker.getId() << ": " << weights);

  // for testing we check whether all weighted scalar products now come out as 1.
#ifndef NDEBUG
  for (std::vector<Vector>::const_iterator iter = BondVectors.begin();
      iter != BondVectors.end(); ++iter) {
    std::vector<double> scps;
    scps.reserve(BondVectors.size());
    std::transform(
        BondVectors.begin(), BondVectors.end(),
        weights.begin(),
        std::back_inserter(scps),
        boost::bind(static_cast< double (*)(double) >(&fabs),
            boost::bind(std::multiplies<double>(),
                boost::bind(&Vector::ScalarProduct, boost::cref(*iter), _1),
                _2))
        );
    const double scp_sum = std::accumulate(scps.begin(), scps.end(), 0.);
    ASSERT( fabs(scp_sum - 1.) < MYEPSILON,
        "ForceAnnealing::operator() - for BondVector "+toString(*iter)
        +" we have weighted scalar product of "+toString(scp_sum)+" != 1.");
  }
#endif
  return weights;
}