//

//  Copyright (C) 2004-2015 Greg Landrum and Rational Discovery LLC

//

//   @@ 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.

//

//! \file Ranking.h

/*!

    \brief Utility functionality used to rank sequences

    Much of this used to be in GraphMol/RankAtoms.h

*/

#include <RDGeneral/export.h>

#ifndef RD_RANKING_H

#define RD_RANKING_H

#include <vector>

#include <functional>

#include <algorithm>

#include <cstdint>

namespace Rankers {

inline auto pairGreater = [](const auto &v1, const auto &v2) {

  return v1.first > v2.first;

};

//! function for implementing < on two std::pairs.  The first entries are

/// compared.

inline auto pairLess = [](const auto &v1, const auto &v2) {

  return v1.first < v2.first;

};

//! ranks the entries in a vector

/*!

  \param vect the vector to rank

  \param res  is used to return the ranks of each entry

*/

template <typename T1, typename T2>

void rankVect(const std::vector<T1> &vect, T2 &res) {

  PRECONDITION(res.size() >= vect.size(), "vector size mismatch");

  unsigned int nEntries = rdcast<unsigned int>(vect.size());

  std::vector<unsigned int> indices(nEntries);

  for (unsigned int i = 0; i < nEntries; ++i) {

    indices[i] = i;

  }

  std::sort(indices.begin(), indices.end(),

            [&](auto i1, auto i2) { return vect[i1] < vect[i2]; });

  int currRank = 0;

  unsigned int lastIdx = indices[0];

  for (auto idx : indices) {

    if (vect[idx] == vect[lastIdx]) {

      res[idx] = currRank;

    } else {

      res[idx] = ++currRank;

      lastIdx = idx;

    }

  }

}

}  // namespace Rankers

#endif