// 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 trimat_helper
//! @{

namespace trimat_helper {

template <typename eT>
inline bool is_triu(const Mat<eT>& A) {
  arma_debug_sigprint();

  // NOTE: assuming that A has a square size

  const uword N = A.n_rows;
  const uword Nm1 = N - 1;

  if (N < 2) {
    return false;
  }

  const eT* A_col = A.memptr();
  const eT eT_zero = eT(0);

  // quickly check element at bottom-left

  if (A_col[Nm1] != eT_zero) {
    return false;
  }

  // if we got to this point, do a thorough check

  for (uword j = 0; j < Nm1; ++j) {
    for (uword i = (j + 1); i < N; ++i) {
      const eT A_ij = A_col[i];

      if (A_ij != eT_zero) {
        return false;
      }
    }

    A_col += N;
  }

  return true;
}

template <typename eT>
inline bool is_tril(const Mat<eT>& A) {
  arma_debug_sigprint();

  // NOTE: assuming that A has a square size

  const uword N = A.n_rows;

  if (N < 2) {
    return false;
  }

  const eT eT_zero = eT(0);

  // quickly check element at top-right

  const eT* A_colNm1 = A.colptr(N - 1);

  if (A_colNm1[0] != eT_zero) {
    return false;
  }

  // if we got to this point, do a thorough check

  const eT* A_col = A.memptr() + N;

  for (uword j = 1; j < N; ++j) {
    for (uword i = 0; i < j; ++i) {
      const eT A_ij = A_col[i];

      if (A_ij != eT_zero) {
        return false;
      }
    }

    A_col += N;
  }

  return true;
}

template <typename eT>
inline bool has_nonfinite_tril(const Mat<eT>& A) {
  arma_debug_sigprint();

  // NOTE: assuming that A has a square size

  const eT* colptr = A.memptr();
  const uword N = A.n_rows;

  for (uword i = 0; i < N; ++i) {
    const uword len = N - i;

    if (arrayops::is_finite(&(colptr[i]), len) == false) {
      return true;
    }

    colptr += N;
  }

  return false;
}

template <typename eT>
inline bool has_nonfinite_triu(const Mat<eT>& A) {
  arma_debug_sigprint();

  // NOTE: assuming that A has a square size

  const eT* colptr = A.memptr();
  const uword N = A.n_rows;

  for (uword i = 0; i < N; ++i) {
    const uword len = i + 1;

    if (arrayops::is_finite(colptr, len) == false) {
      return true;
    }

    colptr += N;
  }

  return false;
}

}  // end of namespace trimat_helper

//! @}
