// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
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// Author: richie.stebbing@gmail.com (Richard Stebbing)

#include "ceres/dynamic_compressed_row_sparse_matrix.h"

#include <cstring>

namespace ceres::internal {

DynamicCompressedRowSparseMatrix::DynamicCompressedRowSparseMatrix(
    int num_rows, int num_cols, int initial_max_num_nonzeros)
    : CompressedRowSparseMatrix(num_rows, num_cols, initial_max_num_nonzeros) {
  dynamic_cols_.resize(num_rows);
  dynamic_values_.resize(num_rows);
}

void DynamicCompressedRowSparseMatrix::InsertEntry(int row,
                                                   int col,
                                                   const double& value) {
  CHECK_GE(row, 0);
  CHECK_LT(row, num_rows());
  CHECK_GE(col, 0);
  CHECK_LT(col, num_cols());
  dynamic_cols_[row].push_back(col);
  dynamic_values_[row].push_back(value);
}

void DynamicCompressedRowSparseMatrix::ClearRows(int row_start, int num_rows) {
  for (int r = 0; r < num_rows; ++r) {
    const int i = row_start + r;
    CHECK_GE(i, 0);
    CHECK_LT(i, this->num_rows());
    dynamic_cols_[i].resize(0);
    dynamic_values_[i].resize(0);
  }
}

void DynamicCompressedRowSparseMatrix::Finalize(int num_additional_elements) {
  // `num_additional_elements` is provided as an argument so that additional
  // storage can be reserved when it is known by the finalizer.
  CHECK_GE(num_additional_elements, 0);

  // Count the number of non-zeros and resize `cols_` and `values_`.
  int num_jacobian_nonzeros = 0;
  for (const auto& dynamic_col : dynamic_cols_) {
    num_jacobian_nonzeros += dynamic_col.size();
  }

  SetMaxNumNonZeros(num_jacobian_nonzeros + num_additional_elements);

  // Flatten `dynamic_cols_` into `cols_` and `dynamic_values_`
  // into `values_`.
  int index_into_values_and_cols = 0;
  for (int i = 0; i < num_rows(); ++i) {
    mutable_rows()[i] = index_into_values_and_cols;
    const int num_nonzero_columns = dynamic_cols_[i].size();
    if (num_nonzero_columns > 0) {
      memcpy(mutable_cols() + index_into_values_and_cols,
             &dynamic_cols_[i][0],
             dynamic_cols_[i].size() * sizeof(dynamic_cols_[0][0]));
      memcpy(mutable_values() + index_into_values_and_cols,
             &dynamic_values_[i][0],
             dynamic_values_[i].size() * sizeof(dynamic_values_[0][0]));
      index_into_values_and_cols += dynamic_cols_[i].size();
    }
  }
  mutable_rows()[num_rows()] = index_into_values_and_cols;

  CHECK_EQ(index_into_values_and_cols, num_jacobian_nonzeros)
      << "Ceres bug: final index into values_ and cols_ should be equal to "
      << "the number of jacobian nonzeros. Please contact the developers!";
}

}  // namespace ceres::internal