/*
 *  Copyright 2008-2009 NVIDIA Corporation
 *
 *  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.
 */

/*! \file ell_matrix.h
 *  \brief ELLPACK/ITPACK matrix format.
 */

#pragma once

#include <cusp/detail/config.h>

#include <cusp/format.h>
#include <cusp/memory.h>
#include <cusp/detail/matrix_base.h>
#include <cusp/detail/utils.h>

namespace cusp
{

    // Forward definitions
    struct column_major;
    template<typename ValueType, class MemorySpace, class Orientation> class array2d;
    template<typename Array, class Orientation>                        class array2d_view;
    template <typename Array1, typename Array2, typename IndexType, typename ValueType, typename MemorySpace> class ell_matrix_view;

/*! \addtogroup sparse_matrices Sparse Matrices
 */

/*! \addtogroup sparse_matrix_containers Sparse Matrix Containers
 *  \ingroup sparse_matrices
 *  \{
 */

/*! \p ell_matrix : ELLPACK/ITPACK matrix container
 *
 * \tparam IndexType Type used for matrix indices (e.g. \c int).
 * \tparam ValueType Type used for matrix values (e.g. \c float).
 * \tparam MemorySpace A memory space (e.g. \c cusp::host_memory or cusp::device_memory)
 *
 * \note The matrix entries must be sorted by column index.
 * \note The matrix entries within each row should be shifted to the left.
 * \note The matrix should not contain duplicate entries.
 *
 *  The following code snippet demonstrates how to create a 4-by-3
 *  \p ell_matrix on the host with 3 nonzeros per row (6 total nonzeros)
 *  and then copies the matrix to the device.
 *
 *  \code
 *  #include <cusp/ell_matrix.h>
 *  ...
 *
 *  // allocate storage for (4,3) matrix with 6 nonzeros and at most 3 nonzeros per row.
 *  cusp::ell_matrix<int,float,cusp::host_memory> A(4,3,6,3);
 *
 *  // X is used to fill unused entries in the matrix
 *  const int X = cusp::ell_matrix<int,float,cusp::host_memory>::invalid_index;
 *
 *  // initialize matrix entries on host
 *  A.column_indices(0,0) = 0; A.values(0,0) = 10;
 *  A.column_indices(0,1) = 2; A.values(0,1) = 20;  // shifted to leftmost position
 *  A.column_indices(0,2) = X; A.values(0,2) =  0;  // padding
 *
 *  A.column_indices(1,0) = X; A.values(1,0) =  0;  // padding
 *  A.column_indices(1,1) = X; A.values(1,1) =  0;  // padding
 *  A.column_indices(1,2) = X; A.values(1,2) =  0;  // padding
 *
 *  A.column_indices(2,0) = 2; A.values(2,0) = 30;  // shifted to leftmost position
 *  A.column_indices(2,1) = X; A.values(2,1) =  0;  // padding
 *  A.column_indices(2,2) = X; A.values(2,2) =  0;  // padding
 *
 *  A.column_indices(3,0) = 0; A.values(3,0) = 40;
 *  A.column_indices(3,1) = 1; A.values(3,1) = 50;
 *  A.column_indices(3,2) = 2; A.values(3,2) = 60;
 *
 *  // A now represents the following matrix
 *  //    [10  0 20]
 *  //    [ 0  0  0]
 *  //    [ 0  0 30]
 *  //    [40 50 60]
 *
 *  // copy to the device
 *  cusp::ell_matrix<int,float,cusp::device_memory> B = A;
 *  \endcode
 *
 */
template <typename IndexType, typename ValueType, class MemorySpace>
class ell_matrix : public detail::matrix_base<IndexType,ValueType,MemorySpace,cusp::ell_format>
{
  typedef cusp::detail::matrix_base<IndexType,ValueType,MemorySpace,cusp::ell_format> Parent;
  public:
    /*! rebind matrix to a different MemorySpace
     */
    template<typename MemorySpace2>
    struct rebind { typedef cusp::ell_matrix<IndexType, ValueType, MemorySpace2> type; };
    
    /*! type of column indices array
     */
    typedef typename cusp::array2d<IndexType, MemorySpace, cusp::column_major> column_indices_array_type;
    
    /*! type of values array
     */
    typedef typename cusp::array2d<ValueType, MemorySpace, cusp::column_major> values_array_type;
    
    /*! equivalent container type
     */
    typedef typename cusp::ell_matrix<IndexType, ValueType, MemorySpace> container;

    /*! equivalent view type
     */
    typedef typename cusp::ell_matrix_view<typename column_indices_array_type::view,
                                           typename values_array_type::view,
                                           IndexType, ValueType, MemorySpace> view;
    
    /*! equivalent const_view type
     */
    typedef typename cusp::ell_matrix_view<typename column_indices_array_type::const_view,
                                           typename values_array_type::const_view,
                                           IndexType, ValueType, MemorySpace> const_view;


    /*! Value used to pad the rows of the column_indices array.
     */
    const static IndexType invalid_index = static_cast<IndexType>(-1);
    
    /*! Storage for the column indices of the ELL data structure.
     */
    column_indices_array_type column_indices;

    /*! Storage for the nonzero entries of the ELL data structure.
     */
    values_array_type values;

    /*! Construct an empty \p ell_matrix.
     */
    ell_matrix() {}

    /*! Construct an \p ell_matrix with a specific shape, number of nonzero entries,
     *  and maximum number of nonzero entries per row.
     *
     *  \param num_rows Number of rows.
     *  \param num_cols Number of columns.
     *  \param num_entries Number of nonzero matrix entries.
     *  \param num_entries_per_row Maximum number of nonzeros per row.
     *  \param alignment Amount of padding used to align the data structure (default 32).
     */
    ell_matrix(size_t num_rows, size_t num_cols, size_t num_entries,
               size_t num_entries_per_row, size_t alignment = 32)
      : Parent(num_rows, num_cols, num_entries)
    {
      // TODO use array2d constructor when it can accept pitch
      column_indices.resize(num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
      values.resize        (num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
    }

    /*! Construct an \p ell_matrix from another matrix.
     *
     *  \param matrix Another sparse or dense matrix.
     */
    template <typename MatrixType>
    ell_matrix(const MatrixType& matrix);
    
    /*! Resize matrix dimensions and underlying storage
     */
    void resize(size_t num_rows, size_t num_cols, size_t num_entries,
                size_t num_entries_per_row)
    {
      Parent::resize(num_rows, num_cols, num_entries);
      column_indices.resize(num_rows, num_entries_per_row);
      values.resize(num_rows, num_entries_per_row);
    }
               
    /*! Resize matrix dimensions and underlying storage
     */
    void resize(size_t num_rows, size_t num_cols, size_t num_entries,
                size_t num_entries_per_row, size_t alignment)
    {
      Parent::resize(num_rows, num_cols, num_entries);
      column_indices.resize(num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
      values.resize        (num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
    }
    
    /*! Swap the contents of two \p ell_matrix objects.
     *
     *  \param matrix Another \p ell_matrix with the same IndexType and ValueType.
     */
    void swap(ell_matrix& matrix)
    {
      Parent::swap(matrix);
      column_indices.swap(matrix.column_indices);
      values.swap(matrix.values);
    }
    
    /*! Assignment from another matrix.
     *
     *  \param matrix Another sparse or dense matrix.
     */
    template <typename MatrixType>
    ell_matrix& operator=(const MatrixType& matrix);
}; // class ell_matrix
/*! \}
 */
    
    
/*! \addtogroup sparse_matrix_views Sparse Matrix Views
 *  \ingroup sparse_matrices
 *  \{
 */

/*! \p ell_matrix_view : ELLPACK/ITPACK matrix view
 *
 * \tparam Array1 Type of \c column_indices array view
 * \tparam Array2 Type of \c values array view
 * \tparam IndexType Type used for matrix indices (e.g. \c int).
 * \tparam ValueType Type used for matrix values (e.g. \c float).
 * \tparam MemorySpace A memory space (e.g. \c cusp::host_memory or cusp::device_memory)
 *
 */
template <typename Array1,
          typename Array2,
          typename IndexType   = typename Array1::value_type,
          typename ValueType   = typename Array2::value_type,
          typename MemorySpace = typename cusp::minimum_space<typename Array1::memory_space, typename Array2::memory_space>::type >
class ell_matrix_view : public detail::matrix_base<IndexType,ValueType,MemorySpace,cusp::ell_format>
{
  typedef cusp::detail::matrix_base<IndexType,ValueType,MemorySpace,cusp::ell_format> Parent;
  public:
    /*! type of \c column_indices array
     */
    typedef Array1 column_indices_array_type;
    
    /*! type of \c values array
     */
    typedef Array2 values_array_type;
    
    /*! equivalent container type
     */
    typedef typename cusp::ell_matrix<IndexType, ValueType, MemorySpace> container;

    /*! equivalent view type
     */
    typedef typename cusp::ell_matrix_view<Array1, Array2, IndexType, ValueType, MemorySpace> view;

    /*! Value used to pad the rows of the column_indices array.
     */
    const static IndexType invalid_index = static_cast<IndexType>(-1);
    
    /*! View to column indices of the ELL data structure.
     */
    column_indices_array_type column_indices;

    /*! View to nonzero entries of the ELL data structure.
     */
    values_array_type values;

    /*! Construct an empty \p ell_matrix_view.
     */
    ell_matrix_view() {}

    template <typename OtherArray1, typename OtherArray2>
    ell_matrix_view(size_t num_rows, size_t num_cols, size_t num_entries,
                    OtherArray1& column_indices, OtherArray2& values)
    : Parent(num_rows, num_cols, num_entries), column_indices(column_indices), values(values) {}

    template <typename OtherArray1, typename OtherArray2>
    ell_matrix_view(size_t num_rows, size_t num_cols, size_t num_entries,
                    const OtherArray1& column_indices, const OtherArray2& values)
    : Parent(num_rows, num_cols, num_entries), column_indices(column_indices), values(values) {}
    
    template <typename Matrix>
    ell_matrix_view(Matrix& A)
    : Parent(A), column_indices(A.column_indices), values(A.values) {}
    
    template <typename Matrix>
    ell_matrix_view(const Matrix& A)
    : Parent(A), column_indices(A.column_indices), values(A.values) {}
    
    /*! Resize matrix dimensions and underlying storage
     */
    void resize(size_t num_rows, size_t num_cols, size_t num_entries,
                size_t num_entries_per_row)
    {
      Parent::resize(num_rows, num_cols, num_entries);
      column_indices.resize(num_rows, num_entries_per_row);
      values.resize(num_rows, num_entries_per_row);
    }
               
    /*! Resize matrix dimensions and underlying storage
     */
    void resize(size_t num_rows, size_t num_cols, size_t num_entries,
                size_t num_entries_per_row, size_t alignment)
    {
      Parent::resize(num_rows, num_cols, num_entries);
      column_indices.resize(num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
      values.resize        (num_rows, num_entries_per_row, detail::round_up(num_rows, alignment));
    }
}; // class ell_matrix_view

  
template <typename Array1,
          typename Array2>
ell_matrix_view<Array1,Array2>
make_ell_matrix_view(size_t num_rows,
                     size_t num_cols,
                     size_t num_entries,
                     Array1 column_indices,
                     Array2 values);

template <typename Array1,
          typename Array2,
          typename IndexType,
          typename ValueType,
          typename MemorySpace>
ell_matrix_view<Array1,Array2,IndexType,ValueType,MemorySpace>
make_ell_matrix_view(const ell_matrix_view<Array1,Array2,IndexType,ValueType,MemorySpace>& m);
    
template <typename IndexType, typename ValueType, class MemorySpace>
typename ell_matrix<IndexType,ValueType,MemorySpace>::view
make_ell_matrix_view(ell_matrix<IndexType,ValueType,MemorySpace>& m);

template <typename IndexType, typename ValueType, class MemorySpace>
typename ell_matrix<IndexType,ValueType,MemorySpace>::const_view
make_ell_matrix_view(const ell_matrix<IndexType,ValueType,MemorySpace>& m);
/*! \}
 */

} // end namespace cusp

#include <cusp/array2d.h>
#include <cusp/detail/ell_matrix.inl>