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/* Author: Ioan Sucan */

#ifndef OMPL_BASE_STATE_SAMPLER_ARRAY_
#define OMPL_BASE_STATE_SAMPLER_ARRAY_

#include "ompl/base/SpaceInformation.h"
#include "ompl/base/StateSampler.h"
#include "ompl/base/ValidStateSampler.h"
#include <vector>

namespace ompl
{
    namespace base
    {
        /** \brief Depending on the type of state sampler, we have different allocation routines

            This struct will provide that allocation routine,
            depending on the template argument of ompl::base::SamplerType.*/
        template <typename T>
        struct SamplerSelector
        {
        };

        /** \cond IGNORE */
        template <>
        struct SamplerSelector<StateSampler>
        {
            typedef StateSampler Sampler;
            typedef StateSamplerPtr SamplerPtr;

            SamplerPtr allocStateSampler(const SpaceInformation *si)
            {
                return si->allocStateSampler();
            }
        };

        template <>
        struct SamplerSelector<ValidStateSampler>
        {
            typedef ValidStateSampler Sampler;
            typedef ValidStateSamplerPtr SamplerPtr;

            SamplerPtr allocStateSampler(const SpaceInformation *si)
            {
                return si->allocValidStateSampler();
            }
        };
        /** \endcond */

        /** \brief Class to ease the creation of a set of samplers. This is especially useful for multi-threaded
         * planners. */
        template <typename T>
        class StateSamplerArray
        {
        public:
            /** \brief Pointer to the type of sampler allocated */
            typedef typename SamplerSelector<T>::SamplerPtr SamplerPtr;

            /** \brief The type of sampler allocated */
            typedef typename SamplerSelector<T>::Sampler Sampler;

            /** \brief Constructor */
            StateSamplerArray(const SpaceInformationPtr &si) : si_(si.get())
            {
            }

            /** \brief Constructor */
            StateSamplerArray(const SpaceInformation *si) : si_(si)
            {
            }

            ~StateSamplerArray() = default;

            /** \brief Access operator for a specific sampler. For
                performance reasons, the bounds are not checked. */
            Sampler *operator[](std::size_t index) const
            {
                return samplers_[index].get();
            }

            /** \brief Create or release some state samplers */
            void resize(std::size_t count)
            {
                if (samplers_.size() > count)
                    samplers_.resize(count);
                else if (samplers_.size() < count)
                {
                    std::size_t c = samplers_.size();
                    samplers_.resize(count);
                    for (std::size_t i = c; i < count; ++i)
                        samplers_[i] = ss_.allocStateSampler(si_);
                }
            }

            /** \brief Get the count of samplers currently available */
            std::size_t size() const
            {
                return samplers_.size();
            }

            /** \brief Clear all allocated samplers */
            void clear()
            {
                resize(0);
            }

        private:
            const SpaceInformation *si_;
            SamplerSelector<T> ss_;
            std::vector<SamplerPtr> samplers_;
        };
    }
}

#endif
