// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2017 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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//
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// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// A simple C++ interface to the Eigen's Sparse Cholesky routines.

#ifndef CERES_INTERNAL_EIGENSPARSE_H_
#define CERES_INTERNAL_EIGENSPARSE_H_

// This include must come before any #ifndef check on Ceres compile options.
#include "ceres/internal/config.h"

#ifdef CERES_USE_EIGEN_SPARSE

#include <memory>
#include <string>

#include "Eigen/SparseCore"
#include "ceres/internal/export.h"
#include "ceres/linear_solver.h"
#include "ceres/sparse_cholesky.h"

namespace ceres::internal {

class EigenSparse {
 public:
  static constexpr bool IsNestedDissectionAvailable() noexcept {
#ifdef CERES_NO_EIGEN_METIS
    return false;
#else
    return true;
#endif
  }
};

class CERES_NO_EXPORT EigenSparseCholesky : public SparseCholesky {
 public:
  // Factory
  static std::unique_ptr<SparseCholesky> Create(
      const OrderingType ordering_type);

  // SparseCholesky interface.
  ~EigenSparseCholesky() override;
  LinearSolverTerminationType Factorize(CompressedRowSparseMatrix* lhs,
                                        std::string* message) override = 0;
  CompressedRowSparseMatrix::StorageType StorageType() const override = 0;
  LinearSolverTerminationType Solve(const double* rhs,
                                    double* solution,
                                    std::string* message) override = 0;
};

// Even though the input is double precision linear system, this class
// solves it by computing a single precision Cholesky factorization.
class CERES_NO_EXPORT FloatEigenSparseCholesky : public SparseCholesky {
 public:
  // Factory
  static std::unique_ptr<SparseCholesky> Create(
      const OrderingType ordering_type);

  // SparseCholesky interface.
  ~FloatEigenSparseCholesky() override;
  LinearSolverTerminationType Factorize(CompressedRowSparseMatrix* lhs,
                                        std::string* message) override = 0;
  CompressedRowSparseMatrix::StorageType StorageType() const override = 0;
  LinearSolverTerminationType Solve(const double* rhs,
                                    double* solution,
                                    std::string* message) override = 0;
};

}  // namespace ceres::internal

#else

namespace ceres::internal {

class EigenSparse {
 public:
  static constexpr bool IsNestedDissectionAvailable() noexcept { return false; }
};

}  // namespace ceres::internal

#endif  // CERES_USE_EIGEN_SPARSE

#endif  // CERES_INTERNAL_EIGENSPARSE_H_