// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

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//

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

#include <cmath>

#include <limits>

#include "gtest/gtest.h"

#include "ceres/parameter_block.h"

#include "ceres/residual_block.h"

#include "ceres/residual_block_utils.h"

#include "ceres/cost_function.h"

#include "ceres/internal/scoped_ptr.h"

#include "ceres/sized_cost_function.h"

namespace ceres {

namespace internal {

// Routine to check if ResidualBlock::Evaluate for unary CostFunction

// with one residual succeeds with true or dies.

void CheckEvaluation(const CostFunction& cost_function, bool is_good) {

  double x = 1.0;

  ParameterBlock parameter_block(&x, 1, -1);

  std::vector<ParameterBlock*> parameter_blocks;

  parameter_blocks.push_back(&parameter_block);

  ResidualBlock residual_block(&cost_function,

                               NULL,

                               parameter_blocks,

                               -1);

  scoped_array<double> scratch(

      new double[residual_block.NumScratchDoublesForEvaluate()]);

  double cost;

  double residuals;

  double jacobian;

  double* jacobians[] = { &jacobian };

  EXPECT_EQ(residual_block.Evaluate(true,

                                    &cost,

                                    &residuals,

                                    jacobians,

                                    scratch.get()), is_good);

}

// A CostFunction that behaves normaly, i.e., it computes numerically

// valid residuals and jacobians.

class GoodCostFunction: public SizedCostFunction<1, 1> {

 public:

  virtual bool Evaluate(double const* const* parameters,

                        double* residuals,

                        double** jacobians) const {

    residuals[0] = 1;

    if (jacobians != NULL && jacobians[0] != NULL) {

      jacobians[0][0] = 0.0;

    }

    return true;

  }

};

// The following four CostFunctions simulate the different ways in

// which user code can cause ResidualBlock::Evaluate to fail.

class NoResidualUpdateCostFunction: public SizedCostFunction<1, 1> {

 public:

  virtual bool Evaluate(double const* const* parameters,

                        double* residuals,

                        double** jacobians) const {

    // Forget to update the residuals.

    // residuals[0] = 1;

    if (jacobians != NULL && jacobians[0] != NULL) {

      jacobians[0][0] = 0.0;

    }

    return true;

  }

};

class NoJacobianUpdateCostFunction: public SizedCostFunction<1, 1> {

 public:

  virtual bool Evaluate(double const* const* parameters,

                        double* residuals,

                        double** jacobians) const {

    residuals[0] = 1;

    if (jacobians != NULL && jacobians[0] != NULL) {

      // Forget to update the jacobians.

      // jacobians[0][0] = 0.0;

    }

    return true;

  }

};

class BadResidualCostFunction: public SizedCostFunction<1, 1> {

 public:

  virtual bool Evaluate(double const* const* parameters,

                        double* residuals,

                        double** jacobians) const {

    residuals[0] = std::numeric_limits<double>::infinity();

    if (jacobians != NULL && jacobians[0] != NULL) {

      jacobians[0][0] = 0.0;

    }

    return true;

  }

};

class BadJacobianCostFunction: public SizedCostFunction<1, 1> {

 public:

  virtual bool Evaluate(double const* const* parameters,

                        double* residuals,

                        double** jacobians) const {

    residuals[0] = 1.0;

    if (jacobians != NULL && jacobians[0] != NULL) {

      jacobians[0][0] = std::numeric_limits<double>::quiet_NaN();

    }

    return true;

  }

};

// Note: It is preferable to write the below test as:

//

//  CheckEvaluation(GoodCostFunction(), true);

//  CheckEvaluation(NoResidualUpdateCostFunction(), false);

//  CheckEvaluation(NoJacobianUpdateCostFunction(), false);

//  ...

//

// however, there is a bug in the version of GCC on Mac OS X we tested, which

// requires the objects get put into local variables instead of getting

// instantiated on the stack.

TEST(ResidualBlockUtils, CheckAllCombinationsOfBadness) {

  GoodCostFunction good_fun;

  CheckEvaluation(good_fun, true);

  NoResidualUpdateCostFunction no_residual;

  CheckEvaluation(no_residual, false);

  NoJacobianUpdateCostFunction no_jacobian;

  CheckEvaluation(no_jacobian, false);

  BadResidualCostFunction bad_residual;

  CheckEvaluation(bad_residual, false);

  BadJacobianCostFunction bad_jacobian;

  CheckEvaluation(bad_jacobian, false);

}

}  // namespace internal

}  // namespace ceres