// $Id$
//
//  Copyright (C) 2012 Greg Landrum
//
//   @@ All Rights Reserved @@
//  This file is part of the RDKit.
//  The contents are covered by the terms of the BSD license
//  which is included in the file license.txt, found at the root
//  of the RDKit source tree.
//
#include <RDGeneral/Invariant.h>
#include <GraphMol/GraphMol.h>
#include <GraphMol/PeriodicTable.h>
#include <GraphMol/MolOps.h>
#include <GraphMol/Subgraphs/Subgraphs.h>
#include "MolDescriptors.h"
#include "ConnectivityDescriptors.h"

namespace RDKit {
namespace Descriptors {
namespace detail {
void hkDeltas(const ROMol &mol, std::vector<double> &deltas, bool force) {
  PRECONDITION(deltas.size() >= mol.getNumAtoms(), "bad vector size");
  if (!force && mol.hasProp(common_properties::_connectivityHKDeltas)) {
    mol.getProp(common_properties::_connectivityHKDeltas, deltas);
    return;
  }
  const PeriodicTable *tbl = PeriodicTable::getTable();
  ROMol::VERTEX_ITER atBegin, atEnd;
  boost::tie(atBegin, atEnd) = mol.getVertices();
  while (atBegin != atEnd) {
    const Atom* at = mol[*atBegin];
    unsigned int n = at->getAtomicNum();
    if (n <= 1) {
      deltas[at->getIdx()] = 0;
    } else if (n <= 10) {
      deltas[at->getIdx()] = tbl->getNouterElecs(n) - at->getTotalNumHs();
    } else {
      deltas[at->getIdx()] =
          double(tbl->getNouterElecs(n) - at->getTotalNumHs()) /
          (n - tbl->getNouterElecs(n) - 1);
    }
    if (deltas[at->getIdx()] != 0.0)
      deltas[at->getIdx()] = 1. / sqrt(deltas[at->getIdx()]);
    ++atBegin;
  }
  mol.setProp(common_properties::_connectivityHKDeltas, deltas, true);
}

void nVals(const ROMol &mol, std::vector<double> &nVs, bool force) {
  PRECONDITION(nVs.size() >= mol.getNumAtoms(), "bad vector size");
  if (!force && mol.hasProp(common_properties::_connectivityNVals)) {
    mol.getProp(common_properties::_connectivityNVals, nVs);
    return;
  }
  const PeriodicTable *tbl = PeriodicTable::getTable();
  ROMol::VERTEX_ITER atBegin, atEnd;
  boost::tie(atBegin, atEnd) = mol.getVertices();
  while (atBegin != atEnd) {
    const Atom* at = mol[*atBegin];
    double v = tbl->getNouterElecs(at->getAtomicNum()) - at->getTotalNumHs();
    if (v != 0.0) {
      v = 1. / sqrt(v);
    }
    nVs[at->getIdx()] = v;
    ++atBegin;
  }
  mol.setProp(common_properties::_connectivityNVals, nVs, true);
}

double getAlpha(const Atom &atom, bool &found) {
  double res = 0.0;
  found = false;
  switch (atom.getAtomicNum()) {
    case 1:
      res = 0.0;
      found = true;
      break;
    case 6:
      switch (atom.getHybridization()) {
        case Atom::SP:
          res = -0.22;
          found = true;
          break;
        case Atom::SP2:
          res = -0.13;
          found = true;
          break;
        default:
          res = 0.00;
          found = true;
      };
      break;
    case 7:
      switch (atom.getHybridization()) {
        case Atom::SP:
          res = -0.29;
          found = true;
          break;
        case Atom::SP2:
          res = -0.20;
          found = true;
          break;
        default:
          res = -0.04;
          found = true;
          break;
      };
      break;
    case 8:
      switch (atom.getHybridization()) {
        case Atom::SP2:
          res = -0.20;
          found = true;
          break;
        default:
          res = -0.04;
          found = true;
          break;
      };
      break;
    case 9:
      res = -0.07;
      found = true;
      break;
    case 15:
      switch (atom.getHybridization()) {
        case Atom::SP2:
          res = 0.30;
          found = true;
          break;
        default:
          res = 0.43;
          found = true;
          break;
      };
      break;
    case 16:
      switch (atom.getHybridization()) {
        case Atom::SP2:
          res = 0.22;
          found = true;
          break;
        default:
          res = 0.35;
          found = true;
          break;
      };
      break;
    case 17:
      res = 0.29;
      found = true;
      break;
    case 35:
      res = 0.48;
      found = true;
      break;
    case 53:
      res = 0.73;
      found = true;
      break;
    default:
      break;
  }
  return res;
}
}  // end of detail namespace

double calcChiNv(const ROMol &mol, unsigned int n, bool force) {
  std::vector<double> hkDs(mol.getNumAtoms());
  detail::hkDeltas(mol, hkDs, force);
  PATH_LIST ps = findAllPathsOfLengthN(mol, n + 1, false);
  double res = 0.0;
  BOOST_FOREACH (PATH_TYPE p, ps) {
    TEST_ASSERT(p.size() == n + 1);
    double accum = 1.0;
    for (unsigned int i = 0; i < n; ++i) {
      accum *= hkDs[p[i]];
    }
    // only push on the last element if this isn't a ring; this was github 463:
    if (p[n] != p[0]) {
      accum *= hkDs[p[n]];
    }
    res += accum;
  }
  return res;
}
double calcChiNn(const ROMol &mol, unsigned int n, bool force) {
  std::vector<double> nVs(mol.getNumAtoms());
  detail::nVals(mol, nVs, force);
  PATH_LIST ps = findAllPathsOfLengthN(mol, n + 1, false);
  double res = 0.0;
  BOOST_FOREACH (PATH_TYPE p, ps) {
    TEST_ASSERT(p.size() == n + 1);
    double accum = 1.0;
    for (unsigned int i = 0; i < n; ++i) {
      accum *= nVs[p[i]];
    }
    // only push on the last element if this isn't a ring; this was github 463:
    if (p[n] != p[0]) {
      accum *= nVs[p[n]];
    }

    res += accum;
  }
  return res;
}

double calcChi0v(const ROMol &mol, bool force) {
  std::vector<double> hkDs(mol.getNumAtoms());
  detail::hkDeltas(mol, hkDs, force);
  return std::accumulate(hkDs.begin(), hkDs.end(), 0.0);
};
double calcChi1v(const ROMol &mol, bool force) {
  std::vector<double> hkDs(mol.getNumAtoms());
  detail::hkDeltas(mol, hkDs, force);

  double res = 0.0;
  ROMol::EDGE_ITER firstB, lastB;
  boost::tie(firstB, lastB) = mol.getEdges();
  while (firstB != lastB) {
    const Bond* bond = mol[*firstB];
    res += hkDs[bond->getBeginAtomIdx()] * hkDs[bond->getEndAtomIdx()];
    ++firstB;
  }
  return res;
};
double calcChi2v(const ROMol &mol, bool force) {
  return calcChiNv(mol, 2, force);
};
double calcChi3v(const ROMol &mol, bool force) {
  return calcChiNv(mol, 3, force);
};
double calcChi4v(const ROMol &mol, bool force) {
  return calcChiNv(mol, 4, force);
};

double calcChi0n(const ROMol &mol, bool force) {
  std::vector<double> nVs(mol.getNumAtoms());
  detail::nVals(mol, nVs, force);
  return std::accumulate(nVs.begin(), nVs.end(), 0.0);
};
double calcChi1n(const ROMol &mol, bool force) {
  std::vector<double> nVs(mol.getNumAtoms());
  detail::nVals(mol, nVs, force);

  double res = 0.0;
  ROMol::EDGE_ITER firstB, lastB;
  boost::tie(firstB, lastB) = mol.getEdges();
  while (firstB != lastB) {
    const Bond* bond = mol[*firstB];
    res += nVs[bond->getBeginAtomIdx()] * nVs[bond->getEndAtomIdx()];
    ++firstB;
  }
  return res;
};
double calcChi2n(const ROMol &mol, bool force) {
  return calcChiNn(mol, 2, force);
};
double calcChi3n(const ROMol &mol, bool force) {
  return calcChiNn(mol, 3, force);
};
double calcChi4n(const ROMol &mol, bool force) {
  return calcChiNn(mol, 4, force);
};

double calcHallKierAlpha(const ROMol &mol, std::vector<double> *atomContribs) {
  PRECONDITION(!atomContribs || atomContribs->size() >= mol.getNumAtoms(),
               "bad atomContribs vector");
  const PeriodicTable *tbl = PeriodicTable::getTable();
  double alphaSum = 0.0;
  double rC = tbl->getRb0(6);
  ROMol::VERTEX_ITER atBegin, atEnd;
  boost::tie(atBegin, atEnd) = mol.getVertices();
  while (atBegin != atEnd) {
    const Atom* at = mol[*atBegin];
    ++atBegin;
    unsigned int n = at->getAtomicNum();
    if (!n) continue;
    bool found;
    double alpha = detail::getAlpha(*(at), found);
    if (!found) {
      double rA = tbl->getRb0(n);
      alpha = rA / rC - 1.0;
    }
    alphaSum += alpha;
    if (atomContribs) (*atomContribs)[at->getIdx()] = alpha;
  }
  return alphaSum;
};

namespace {
double kappa1Helper(double P1, double A, double alpha) {
  double denom = P1 + alpha;
  double kappa = 0.0;
  if (denom) {
    kappa = (A + alpha) * (A + alpha - 1) * (A + alpha - 1) / (denom * denom);
  }
  return kappa;
}
double kappa2Helper(double P2, double A, double alpha) {
  double denom = (P2 + alpha) * (P2 + alpha);
  double kappa = 0.0;
  if (denom) {
    kappa = (A + alpha - 1) * (A + alpha - 2) * (A + alpha - 2) / denom;
  }
  return kappa;
}
double kappa3Helper(double P3, int A, double alpha) {
  double denom = (P3 + alpha) * (P3 + alpha);
  double kappa = 0.0;
  if (denom) {
    if (A % 2) {
      kappa = (A + alpha - 1) * (A + alpha - 3) * (A + alpha - 3) / denom;
    } else {
      kappa = (A + alpha - 2) * (A + alpha - 3) * (A + alpha - 3) / denom;
    }
  }
  return kappa;
}
}  // end of anonymous namespace

double calcKappa1(const ROMol &mol) {
  double P1 = mol.getNumBonds();
  double A = mol.getNumHeavyAtoms();
  double alpha = calcHallKierAlpha(mol);
  double kappa = kappa1Helper(P1, A, alpha);
  return kappa;
}
double calcKappa2(const ROMol &mol) {
  PATH_LIST ps = findAllPathsOfLengthN(mol, 2);
  double P2 = ps.size();
  double A = mol.getNumHeavyAtoms();
  double alpha = calcHallKierAlpha(mol);
  double kappa = kappa2Helper(P2, A, alpha);
  return kappa;
}
double calcKappa3(const ROMol &mol) {
  double P3 = findAllPathsOfLengthN(mol, 3).size();
  int A = mol.getNumHeavyAtoms();
  double alpha = calcHallKierAlpha(mol);
  double kappa = kappa3Helper(P3, A, alpha);
  return kappa;
}
}  // end of namespace Descriptors
}
