// $Id$
//
//  Copyright (C) 2002-2010 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.
//
#define PY_ARRAY_UNIQUE_SYMBOL Py_Array_API_Clustering

#include <RDBoost/Wrap.h>
#include <cstdint>

namespace python = boost::python;

#include <RDBoost/import_array.h>

typedef double real;

extern "C" void distdriver_(boost::int64_t *n, boost::int64_t *len, real *dists,
                            boost::int64_t *toggle, boost::int64_t *ia,
                            boost::int64_t *ib, real *crit);

//
// Rather than deal with any nonsense like trying to get
// the distance matrix built properly on the f2c side of things
// (thus drowning in the waves of f2c hate), we'll generate
// the distance matrix on our own here and then call distdriver_
//
void clusterit(real *dataP, boost::int64_t n, boost::int64_t m,
               boost::int64_t iopt, boost::int64_t *ia, boost::int64_t *ib,
               real *crit) {
  real *dists;
  boost::int64_t len;
  boost::int64_t pos = 0;
  boost::int64_t i, j, k, iTab, jTab;
  double tmp;
  len = (n * (n - 1)) / 2;
  dists = (real *)calloc(len, sizeof(real));
  CHECK_INVARIANT(dists, "failed to allocate memory");
  for (i = 1; i < n; i++) {
    iTab = i * m;
    for (j = 0; j < i; j++) {
      jTab = j * m;
      for (k = 0; k < m; k++) {
        tmp = dataP[iTab + k] - dataP[jTab + k];
        dists[pos] += tmp * tmp;
      }
      pos++;
    }
  }
  distdriver_(&n, &len, dists, &iopt, ia, ib, crit);
  free(dists);
};

static PyObject *Clustering_MurtaghCluster(python::object data, int nPts,
                                           int sz, int option) {
  PyArrayObject *dataContig;
  boost::int64_t *ia, *ib;
  real *crit;
  PyObject *res;
  PyObject *tmp;
  npy_intp dims[2];

  if (PyArray_Check(data.ptr())) {
    dataContig = reinterpret_cast<PyArrayObject *>(
        PyArray_ContiguousFromObject(data.ptr(), NPY_DOUBLE, 2, 2));
  } else {
    throw_value_error("PyArray_Type expected as input");
    return nullptr;
  }

  ia = (boost::int64_t *)calloc(nPts, sizeof(boost::int64_t));
  ib = (boost::int64_t *)calloc(nPts, sizeof(boost::int64_t));
  crit = (real *)calloc(nPts, sizeof(real));

  clusterit((real *)PyArray_DATA(dataContig), nPts, sz, option, ia, ib, crit);

  dims[0] = nPts;
  res = PyTuple_New(3);

  //  NOTE: these operations maintain pointers to the respective arrays,
  //  that's why it's ok that we do not free them in this function,
  //  Python will take care of it for us.
  //
  tmp = PyArray_SimpleNewFromData(1, dims, NPY_LONG, (void *)ia);
  PyTuple_SetItem(res, 0, (PyObject *)tmp);

  tmp = PyArray_SimpleNewFromData(1, dims, NPY_LONG, (void *)ib);
  PyTuple_SetItem(res, 1, (PyObject *)tmp);

  tmp = PyArray_SimpleNewFromData(1, dims, NPY_DOUBLE, (void *)crit);
  PyTuple_SetItem(res, 2, (PyObject *)tmp);

  return res;
};

void distclusterit(real *dists, boost::int64_t n, boost::int64_t iopt,
                   boost::int64_t *ia, boost::int64_t *ib, real *crit) {
  boost::int64_t len;

  len = (n * (n - 1)) / 2;
  distdriver_(&n, &len, dists, &iopt, ia, ib, crit);
};

static PyObject *Clustering_MurtaghDistCluster(python::object data, int nPts,
                                               int option) {
  PyArrayObject *dataContig;
  boost::int64_t *ia, *ib;
  real *crit;
  PyObject *res = PyTuple_New(3);
  PyObject *tmp;
  npy_intp dims[] = {1};

  if (PyArray_Check(data.ptr())) {
    dataContig = reinterpret_cast<PyArrayObject *>(
        PyArray_ContiguousFromObject(data.ptr(), NPY_DOUBLE, 1, 1));
  } else {
    throw_value_error("PyArray_Type expected as input");
    return nullptr;
  }

  ia = (boost::int64_t *)calloc(nPts, sizeof(boost::int64_t));
  ib = (boost::int64_t *)calloc(nPts, sizeof(boost::int64_t));
  crit = (real *)calloc(nPts, sizeof(real));
  distclusterit((real *)PyArray_DATA(dataContig), nPts, option, ia, ib, crit);

  dims[0] = nPts;

  //
  //  NOTE: these operations maintain pointers to the respective arrays,
  //  that's why it's ok that we do not free them in this function,
  //  Python will take care of it for us.
  //
  tmp = PyArray_SimpleNewFromData(1, dims, NPY_LONG, (void *)ia);
  PyTuple_SetItem(res, 0, tmp);

  tmp = PyArray_SimpleNewFromData(1, dims, NPY_LONG, (void *)ib);
  PyTuple_SetItem(res, 1, tmp);

  tmp = PyArray_SimpleNewFromData(1, dims, NPY_DOUBLE, (void *)crit);
  PyTuple_SetItem(res, 2, tmp);

  return res;
};

BOOST_PYTHON_MODULE(Clustering) {
  rdkit_import_array();

  python::def("MurtaghCluster", Clustering_MurtaghCluster,
              (python::arg("data"), python::arg("nPts"), python::arg("sz"),
               python::arg("option")),
              "TODO: provide docstring");
  python::def("MurtaghDistCluster", Clustering_MurtaghDistCluster,
              (python::arg("data"), python::arg("nPts"), python::arg("option")),
              "TODO: provide docstring");
}
