// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------

//! \addtogroup op_hist
//! @{

template <typename eT>
inline void op_hist::apply_noalias(Mat<uword>& out, const Mat<eT>& A, const uword n_bins,
                                   const uword dim) {
  arma_debug_sigprint();

  arma_conform_check(
      ((A.is_vec() == false) && (A.is_empty() == false)),
      "hist(): only vectors are supported when automatically determining bin centers");

  if (n_bins == 0) {
    out.reset();
    return;
  }

  uword A_n_elem = A.n_elem;
  const eT* A_mem = A.memptr();

  eT min_val = priv::most_pos<eT>();
  eT max_val = priv::most_neg<eT>();

  uword i, j;
  for (i = 0, j = 1; j < A_n_elem; i += 2, j += 2) {
    const eT val_i = A_mem[i];
    const eT val_j = A_mem[j];

    if (min_val > val_i) {
      min_val = val_i;
    }
    if (min_val > val_j) {
      min_val = val_j;
    }

    if (max_val < val_i) {
      max_val = val_i;
    }
    if (max_val < val_j) {
      max_val = val_j;
    }
  }

  if (i < A_n_elem) {
    const eT val_i = A_mem[i];

    if (min_val > val_i) {
      min_val = val_i;
    }
    if (max_val < val_i) {
      max_val = val_i;
    }
  }

  if (min_val == max_val) {
    min_val -= (n_bins / 2);
    max_val += (n_bins / 2);
  }

  if (arma_isfinite(min_val) == false) {
    min_val = priv::most_neg<eT>();
  }
  if (arma_isfinite(max_val) == false) {
    max_val = priv::most_pos<eT>();
  }

  Col<eT> c(n_bins, arma_nozeros_indicator());
  eT* c_mem = c.memptr();

  for (uword ii = 0; ii < n_bins; ++ii) {
    c_mem[ii] = (0.5 + ii) / double(n_bins);
  }

  c = ((max_val - min_val) * c) + min_val;

  glue_hist::apply_noalias(out, A, c, dim);
}

template <typename T1>
inline void op_hist::apply(Mat<uword>& out, const mtOp<uword, T1, op_hist>& X) {
  arma_debug_sigprint();

  const uword n_bins = X.aux_uword_a;

  const quasi_unwrap<T1> U(X.m);

  const uword dim =
      (T1::is_xvec) ? uword(U.M.is_rowvec() ? 1 : 0) : uword((T1::is_row) ? 1 : 0);

  if (is_non_integral<typename T1::elem_type>::value) {
    if (U.is_alias(out)) {
      Mat<uword> tmp;

      op_hist::apply_noalias(tmp, U.M, n_bins, dim);

      out.steal_mem(tmp);
    } else {
      op_hist::apply_noalias(out, U.M, n_bins, dim);
    }
  } else {
    Mat<double> converted = conv_to<Mat<double> >::from(U.M);

    op_hist::apply_noalias(out, converted, n_bins, dim);
  }
}

//! @}
