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/* Author: Luis G. Torres, Jonathan Gammell */

#include "ompl/base/objectives/PathLengthOptimizationObjective.h"
#include <memory>
#if OMPL_HAVE_EIGEN3
#include "ompl/base/samplers/informed/PathLengthDirectInfSampler.h"
#else
#include "ompl/base/samplers/informed/RejectionInfSampler.h"
#endif

ompl::base::PathLengthOptimizationObjective::PathLengthOptimizationObjective(const SpaceInformationPtr &si)
  : ompl::base::OptimizationObjective(si)
{
    description_ = "Path Length";

    // Setup a default cost-to-go heuristics:
    setCostToGoHeuristic(base::goalRegionCostToGo);
}

ompl::base::Cost ompl::base::PathLengthOptimizationObjective::stateCost(const State *s) const
{
    return identityCost();
}

ompl::base::Cost ompl::base::PathLengthOptimizationObjective::motionCost(const State *s1, const State *s2) const
{
    return Cost(si_->distance(s1, s2));
}

ompl::base::Cost ompl::base::PathLengthOptimizationObjective::motionCostHeuristic(const State *s1,
                                                                                  const State *s2) const
{
    return motionCost(s1, s2);
}

ompl::base::InformedSamplerPtr ompl::base::PathLengthOptimizationObjective::allocInformedStateSampler(
    const ProblemDefinitionPtr &probDefn, unsigned int maxNumberCalls) const
{
// Make the direct path-length informed sampler and return. If OMPL was compiled with Eigen, a direct version is
// available, if not a rejection-based technique can be used
#if OMPL_HAVE_EIGEN3
    return std::make_shared<PathLengthDirectInfSampler>(probDefn, maxNumberCalls);
#else
    throw Exception("Direct sampling of the path-length objective requires Eigen, but this version of OMPL was "
                    "compiled without Eigen support. If possible, please install Eigen and recompile OMPL. If this is "
                    "not possible, you can manually create an instantiation of RejectionInfSampler to approximate the "
                    "behaviour of direct informed sampling.");
    // Return a null pointer to avoid compiler warnings
    return ompl::base::InformedSamplerPtr();
#endif
}
