// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
//   used to endorse or promote products derived from this software without
//   specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_GRADIENT_PROBLEM_EVALUATOR_H_
#define CERES_INTERNAL_GRADIENT_PROBLEM_EVALUATOR_H_

#include <map>
#include <memory>
#include <string>

#include "ceres/evaluator.h"
#include "ceres/execution_summary.h"
#include "ceres/gradient_problem.h"
#include "ceres/internal/disable_warnings.h"
#include "ceres/internal/export.h"
#include "ceres/sparse_matrix.h"
#include "ceres/wall_time.h"

namespace ceres::internal {

class CERES_NO_EXPORT GradientProblemEvaluator final : public Evaluator {
 public:
  explicit GradientProblemEvaluator(const GradientProblem& problem)
      : problem_(problem) {}

  std::unique_ptr<SparseMatrix> CreateJacobian() const final { return nullptr; }

  bool Evaluate(const EvaluateOptions& /*evaluate_options*/,
                const double* state,
                double* cost,
                double* /*residuals*/,
                double* gradient,
                SparseMatrix* jacobian) final {
    CHECK(jacobian == nullptr);
    ScopedExecutionTimer total_timer("Evaluator::Total", &execution_summary_);
    // The reason we use Residual and Jacobian here even when we are
    // only computing the cost and gradient has to do with the fact
    // that the line search minimizer code is used by both the
    // GradientProblemSolver and the main CeresSolver coder where the
    // Evaluator evaluates the Jacobian, and these magic strings need
    // to be consistent across the code base for the time accounting
    // to work.
    ScopedExecutionTimer call_type_timer(
        gradient == nullptr ? "Evaluator::Residual" : "Evaluator::Jacobian",
        &execution_summary_);
    return problem_.Evaluate(state, cost, gradient);
  }

  bool Plus(const double* state,
            const double* delta,
            double* state_plus_delta) const final {
    return problem_.Plus(state, delta, state_plus_delta);
  }

  int NumParameters() const final { return problem_.NumParameters(); }

  int NumEffectiveParameters() const final {
    return problem_.NumTangentParameters();
  }

  int NumResiduals() const final { return 1; }

  std::map<std::string, internal::CallStatistics> Statistics() const final {
    return execution_summary_.statistics();
  }

 private:
  const GradientProblem& problem_;
  ::ceres::internal::ExecutionSummary execution_summary_;
};

}  // namespace ceres::internal

#include "ceres/internal/reenable_warnings.h"

#endif  // CERES_INTERNAL_GRADIENT_PROBLEM_EVALUATOR_H_