/*
  Copyright 2024 SINTEF AS

  This file is part of the Open Porous Media project (OPM).

  OPM is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  OPM is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef OPM_DILU_KERNELS_HPP
#define OPM_DILU_KERNELS_HPP

#include <cstddef>
#include <cuda.h>
#include <cuda_runtime.h>
#include <vector>

namespace Opm::gpuistl::detail::DILU
{

/**
 * @brief Perform a lower solve on certain rows in a matrix that can safely be computed in parallel
 * @param reorderedMat pointer to GPU memory containing nonzerovalues of the sparse matrix. The matrix reordered such
 * that rows in the same level sets are contiguous
 * @param rowIndices Pointer to vector on GPU containing row indices compliant wiht bsr format
 * @param colIndices Pointer to vector on GPU containing col indices compliant wiht bsr format
 * @param indexConversion Integer array containing mapping an index in the reordered matrix to its corresponding index
 * in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param dInv The diagonal matrix used by the Diagonal ILU preconditioner. Must be reordered in the same way as
 * reorderedMat
 * @param d Stores the defect
 * @param [out] v Will store the results of the lower solve
 */
template <class T, int blocksize>
void solveLowerLevelSet(T* reorderedMat,
                        int* rowIndices,
                        int* colIndices,
                        int* indexConversion,
                        int startIdx,
                        int rowsInLevelSet,
                        const T* dInv,
                        const T* d,
                        T* v,
                        int threadBlockSize);

/**
 * @brief Perform a lower solve on certain rows in a matrix that can safely be computed in parallel
 * @param reorderedUpperMat pointer to GPU memory containing nonzerovalues of the sparse matrix. The matrix reordered
 * such that rows in the same level sets are contiguous. Thismatrix is assumed to be strictly lower triangular
 * @param rowIndices Pointer to vector on GPU containing row indices compliant wiht bsr format
 * @param colIndices Pointer to vector on GPU containing col indices compliant wiht bsr format
 * @param indexConversion Integer array containing mapping an index in the reordered matrix to its corresponding index
 * in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param dInv The diagonal matrix used by the Diagonal ILU preconditioner. Must be reordered in the same way as
 * reorderedUpperMat
 * @param d Stores the defect
 * @param [out] v Will store the results of the lower solve
 */
template <int blocksize, class LinearSolverScalar, class MatrixScalar>
void solveLowerLevelSetSplit(MatrixScalar* reorderedUpperMat,
                             int* rowIndices,
                             int* colIndices,
                             int* indexConversion,
                             int startIdx,
                             int rowsInLevelSet,
                             const MatrixScalar* dInv,
                             const LinearSolverScalar* d,
                             LinearSolverScalar* v,
                             int threadBlockSize);

/**
 * @brief Perform an upper solve on certain rows in a matrix that can safely be computed in parallel
 * @param reorderedMat pointer to GPU memory containing nonzerovalues of the sparse matrix. The matrix reordered such
 * that rows in the same level sets are contiguous
 * @param rowIndices Pointer to vector on GPU containing row indices compliant wiht bsr format
 * @param colIndices Pointer to vector on GPU containing col indices compliant wiht bsr format
 * @param indexConversion Integer array containing mapping an index in the reordered matrix to its corresponding index
 * in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param dInv The diagonal matrix used by the Diagonal ILU preconditioner
 * @param [out] v Will store the results of the lower solve. To begin with it should store the output from the lower
 * solve
 */
template <class T, int blocksize>
void solveUpperLevelSet(T* reorderedMat,
                        int* rowIndices,
                        int* colIndices,
                        int* indexConversion,
                        int startIdx,
                        int rowsInLevelSet,
                        const T* dInv,
                        T* v,
                        int threadBlockSize);

/**
 * @brief Perform an upper solve on certain rows in a matrix that can safely be computed in parallel
 * @param reorderedUpperMat pointer to GPU memory containing nonzerovalues of the sparse matrix. The matrix reordered
 * such that rows in the same level sets are contiguous. This matrix is assumed to be strictly upper triangular
 * @param rowIndices Pointer to vector on GPU containing row indices compliant wiht bsr format
 * @param colIndices Pointer to vector on GPU containing col indices compliant wiht bsr format
 * @param indexConversion Integer array containing mapping an index in the reordered matrix to its corresponding index
 * in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param dInv The diagonal matrix used by the Diagonal ILU preconditioner
 * @param [out] v Will store the results of the lower solve. To begin with it should store the output from the lower
 * solve
 */
template <int blocksize, class LinearSolverScalar, class MatrixScalar>
void solveUpperLevelSetSplit(MatrixScalar* reorderedUpperMat,
                             int* rowIndices,
                             int* colIndices,
                             int* indexConversion,
                             int startIdx,
                             int rowsInLevelSet,
                             const MatrixScalar* dInv,
                             LinearSolverScalar* v,
                             int threadBlockSize);

/**
 * @brief Computes the ILU0 of the diagonal elements of the reordered matrix and stores it in a reordered vector
 * containing the diagonal blocks
 * @param reorderedMat pointer to GPU memory containing nonzerovalues of the sparse matrix. The matrix reordered such
 * that rows in the same level sets are contiguous
 * @param rowIndices Pointer to vector on GPU containing row indices compliant wiht bsr format
 * @param colIndices Pointer to vector on GPU containing col indices compliant wiht bsr format
 * @param reorderedToNatural Integer array containing mapping an index in the reordered matrix to its corresponding
 * index in the natural ordered matrix
 * @param naturalToreordered Integer array containing mapping an index in the reordered matrix to its corresponding
 * index in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param [out] dInv The diagonal matrix used by the Diagonal ILU preconditioner
 */
template <class T, int blocksize>
void computeDiluDiagonal(T* reorderedMat,
                         int* rowIndices,
                         int* colIndices,
                         int* reorderedToNatural,
                         int* naturalToReordered,
                         int startIdx,
                         int rowsInLevelSet,
                         T* dInv,
                         int threadBlockSize);

/**
 * @brief Computes the ILU0 of the diagonal elements of the split reordered matrix and stores it in a reordered vector
 * containing the diagonal blocks
 * @param reorderedLowerMat pointer to GPU memory containing nonzerovalues of the strictly lower triangular sparse
 * matrix. The matrix reordered such that rows in the same level sets are contiguous
 * @param lowerRowIndices Pointer to vector on GPU containing row indices of the lower matrix compliant wiht bsr format
 * @param lowerColIndices Pointer to vector on GPU containing col indices of the lower matrix compliant wiht bsr format
 * @param reorderedUpperMat pointer to GPU memory containing nonzerovalues of the strictly upper triangular sparse
 * matrix. The matrix reordered such that rows in the same level sets are contiguous
 * @param upperRowIndices Pointer to vector on GPU containing row indices of the upper matrix compliant wiht bsr format
 * @param upperColIndices Pointer to vector on GPU containing col indices of the upper matrix compliant wiht bsr format
 * @param reorderedToNatural Integer array containing mapping an index in the reordered matrix to its corresponding
 * index in the natural ordered matrix
 * @param diagonal The diagonal elements of the reordered matrix
 * @param naturalToreordered Integer array containing mapping an index in the reordered matrix to its corresponding
 * index in the natural ordered matrix
 * @param startIdx Index of the first row of the matrix to be solve
 * @param rowsInLevelSet Number of rows in this level set, which number the amount of rows solved in parallel by this
 * function
 * @param [out] dInv The diagonal matrix used by the Diagonal ILU preconditioner
 */
template <int blocksize, class InputScalar, class OutputScalar, bool copyResultToOtherMatrix>
void computeDiluDiagonalSplit(const InputScalar* srcReorderedLowerMat,
                              int* lowerRowIndices,
                              int* lowerColIndices,
                              const InputScalar* srcReorderedUpperMat,
                              int* upperRowIndices,
                              int* upperColIndices,
                              const InputScalar* srcDiagonal,
                              int* reorderedToNatural,
                              int* naturalToReordered,
                              int startIdx,
                              int rowsInLevelSet,
                              InputScalar* dInv,
                              OutputScalar* dstDiagonal,
                              OutputScalar* dstLowerMat,
                              OutputScalar* dstUpperMat,
                              int threadBlockSize);

} // namespace Opm::gpuistl::detail::DILU
#endif