// 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: sameeragarwal@google.com (Sameer Agarwal)

#include <memory>
#include <utility>

#include "Eigen/Cholesky"
#include "ceres/casts.h"
#include "ceres/compressed_row_sparse_matrix.h"
#include "ceres/context_impl.h"
#include "ceres/internal/config.h"
#include "ceres/internal/eigen.h"
#include "ceres/linear_least_squares_problems.h"
#include "ceres/linear_solver.h"
#include "ceres/triplet_sparse_matrix.h"
#include "ceres/types.h"
#include "gtest/gtest.h"

namespace ceres {
namespace internal {

// TODO(sameeragarwal): These tests needs to be re-written to be more
// thorough, they do not really test the dynamic nature of the
// sparsity.
class DynamicSparseNormalCholeskySolverTest : public ::testing::Test {
 protected:
  void SetUp() final {
    std::unique_ptr<LinearLeastSquaresProblem> problem =
        CreateLinearLeastSquaresProblemFromId(1);
    A_ = CompressedRowSparseMatrix::FromTripletSparseMatrix(
        *down_cast<TripletSparseMatrix*>(problem->A.get()));
    b_ = std::move(problem->b);
    D_ = std::move(problem->D);
  }

  void TestSolver(const LinearSolver::Options& options, double* D) {
    Matrix dense_A;
    A_->ToDenseMatrix(&dense_A);
    Matrix lhs = dense_A.transpose() * dense_A;
    if (D != nullptr) {
      lhs += (ConstVectorRef(D, A_->num_cols()).array() *
              ConstVectorRef(D, A_->num_cols()).array())
                 .matrix()
                 .asDiagonal();
    }

    Vector rhs(A_->num_cols());
    rhs.setZero();
    A_->LeftMultiplyAndAccumulate(b_.get(), rhs.data());
    Vector expected_solution = lhs.llt().solve(rhs);

    std::unique_ptr<LinearSolver> solver(LinearSolver::Create(options));
    LinearSolver::PerSolveOptions per_solve_options;
    per_solve_options.D = D;
    Vector actual_solution(A_->num_cols());
    LinearSolver::Summary summary;
    summary = solver->Solve(
        A_.get(), b_.get(), per_solve_options, actual_solution.data());

    EXPECT_EQ(summary.termination_type, LinearSolverTerminationType::SUCCESS);

    for (int i = 0; i < A_->num_cols(); ++i) {
      EXPECT_NEAR(expected_solution(i), actual_solution(i), 1e-8)
          << "\nExpected: " << expected_solution.transpose()
          << "\nActual: " << actual_solution.transpose();
    }
  }

  void TestSolver(
      const SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,
      const OrderingType ordering_type) {
    LinearSolver::Options options;
    options.type = SPARSE_NORMAL_CHOLESKY;
    options.dynamic_sparsity = true;
    options.sparse_linear_algebra_library_type =
        sparse_linear_algebra_library_type;
    options.ordering_type = ordering_type;
    ContextImpl context;
    options.context = &context;
    TestSolver(options, nullptr);
    TestSolver(options, D_.get());
  }

  std::unique_ptr<CompressedRowSparseMatrix> A_;
  std::unique_ptr<double[]> b_;
  std::unique_ptr<double[]> D_;
};

#ifndef CERES_NO_SUITESPARSE
TEST_F(DynamicSparseNormalCholeskySolverTest, SuiteSparseAMD) {
  TestSolver(SUITE_SPARSE, OrderingType::AMD);
}

#ifndef CERES_NO_CHOLMOD_PARTITION
TEST_F(DynamicSparseNormalCholeskySolverTest, SuiteSparseNESDIS) {
  TestSolver(SUITE_SPARSE, OrderingType::NESDIS);
}
#endif
#endif

#ifdef CERES_USE_EIGEN_SPARSE
TEST_F(DynamicSparseNormalCholeskySolverTest, EigenAMD) {
  TestSolver(EIGEN_SPARSE, OrderingType::AMD);
}

#ifndef CERES_NO_EIGEN_METIS
TEST_F(DynamicSparseNormalCholeskySolverTest, EigenNESDIS) {
  TestSolver(EIGEN_SPARSE, OrderingType::NESDIS);
}
#endif
#endif  // CERES_USE_EIGEN_SPARSE

}  // namespace internal
}  // namespace ceres