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/* Author: Ioan Sucan */

#include "ompl/base/PlannerTerminationCondition.h"
#include "ompl/util/Time.h"
#include <boost/bind.hpp>
#include <boost/thread.hpp>
#include <boost/lambda/bind.hpp>
#include <utility>

namespace ompl
{
    namespace base
    {

        /// @cond IGNORE
        class PlannerTerminationCondition::PlannerTerminationConditionImpl
        {
        public:
            PlannerTerminationConditionImpl(const PlannerTerminationConditionFn &fn, double period) :
            fn_(fn),
            period_(period),
            terminate_(false),
            thread_(NULL),
            evalValue_(false),
            signalThreadStop_(false)
            {
                if (period_ > 0.0)
                    startEvalThread();
            }

            ~PlannerTerminationConditionImpl()
            {
                stopEvalThread();
            }

            bool eval() const
            {
                if (terminate_)
                    return true;
                if (period_ > 0.0)
                    return evalValue_;
                return fn_();
            }

            void terminate() const
            {
                // it is ok to have unprotected write here
                terminate_ = true;
            }

        private:

            /** \brief Start the thread evaluating termination conditions if not already started */
            void startEvalThread()
            {
                if (!thread_)
                {
                    signalThreadStop_ = false;
                    evalValue_ = false;
                    thread_ = new boost::thread(boost::bind(&PlannerTerminationConditionImpl::periodicEval, this));
                }
            }

            /** \brief Stop the thread evaluating termination conditions if not already stopped */
            void stopEvalThread()
            {
                signalThreadStop_ = true;
                if (thread_)
                {
                    thread_->join();
                    delete thread_;
                    thread_ = NULL;
                }
            }

            /** \brief Worker function that runs in a separate thread (calls computeEval())*/
            void periodicEval()
            {
                // we want to check for termination at least once every ms;
                // even though we may evaluate the condition itself more rarely

                unsigned int count = 1;
                time::duration s = time::seconds(period_);
                if (period_ > 0.001)
                {
                    count = 0.5 + period_ / 0.001;
                    s = time::seconds(period_ / (double) count);
                }

                while (!terminate_ && !signalThreadStop_)
                {
                    evalValue_ = fn_();
                    for (unsigned int i = 0 ; i < count ; ++i)
                    {
                        if (terminate_ || signalThreadStop_)
                            break;
                        boost::this_thread::sleep(s);
                    }
                }
            }

            /** \brief Function pointer to the piece of code that decides whether a termination condition has been met */
            PlannerTerminationConditionFn fn_;

            /** \brief Interval of time (seconds) to wait between calls to computeEval() */
            double                        period_;

            /** \brief Flag indicating whether the user has externally requested that the condition for termination should become true */
            mutable bool                  terminate_;

            /** \brief Thread for periodicEval() */
            boost::thread                *thread_;

            /** \brief Cached value returned by fn_() */
            bool                          evalValue_;

            /** \brief Flag used to signal the condition evaluation thread to stop. */
            bool                          signalThreadStop_;
        };

        /// @endcond
    }
}

ompl::base::PlannerTerminationCondition::PlannerTerminationCondition(const PlannerTerminationConditionFn &fn) :
impl_(new PlannerTerminationConditionImpl(fn, -1.0))
{
}

ompl::base::PlannerTerminationCondition::PlannerTerminationCondition(const PlannerTerminationConditionFn &fn, double period) :
impl_(new PlannerTerminationConditionImpl(fn, period))
{
}

void ompl::base::PlannerTerminationCondition::terminate() const
{
    impl_->terminate();
}

bool ompl::base::PlannerTerminationCondition::eval() const
{
    return impl_->eval();
}

ompl::base::PlannerTerminationCondition ompl::base::plannerNonTerminatingCondition()
{
    return PlannerTerminationCondition(boost::lambda::constant(false));
}

ompl::base::PlannerTerminationCondition ompl::base::plannerAlwaysTerminatingCondition()
{
    return PlannerTerminationCondition(boost::lambda::constant(true));
}

/// @cond IGNORE
namespace ompl
{
    namespace base
    {
        static bool plannerOrTerminationConditionAux(const PlannerTerminationCondition &c1, const PlannerTerminationCondition &c2)
        {
            return c1() || c2();
        }

        static bool plannerAndTerminationConditionAux(const PlannerTerminationCondition &c1, const PlannerTerminationCondition &c2)
        {
            return c1() && c2();
        }

        // return true if a certain point in time has passed
        static bool timePassed(const time::point &endTime)
        {
            return time::now() > endTime;
        }
    }
}
/// @endcond

ompl::base::PlannerTerminationCondition ompl::base::plannerOrTerminationCondition(const PlannerTerminationCondition &c1, const PlannerTerminationCondition &c2)
{
    return PlannerTerminationCondition(boost::bind(&plannerOrTerminationConditionAux, c1, c2));
}

ompl::base::PlannerTerminationCondition ompl::base::plannerAndTerminationCondition(const PlannerTerminationCondition &c1, const PlannerTerminationCondition &c2)
{
    return PlannerTerminationCondition(boost::bind(&plannerAndTerminationConditionAux, c1, c2));
}

ompl::base::PlannerTerminationCondition ompl::base::timedPlannerTerminationCondition(double duration)
{
    return timedPlannerTerminationCondition(time::seconds(duration));
}

ompl::base::PlannerTerminationCondition ompl::base::timedPlannerTerminationCondition(time::duration duration)
{
    return PlannerTerminationCondition(boost::bind(&timePassed, time::now() + duration));
}

ompl::base::PlannerTerminationCondition ompl::base::timedPlannerTerminationCondition(double duration, double interval)
{
    if (interval > duration)
        interval = duration;
    return PlannerTerminationCondition(boost::bind(&timePassed, time::now() + time::seconds(duration)), interval);
}

ompl::base::PlannerTerminationCondition ompl::base::exactSolnPlannerTerminationCondition(ompl::base::ProblemDefinitionPtr pdef)
{
    return PlannerTerminationCondition(boost::bind(&ProblemDefinition::hasExactSolution, pdef));
}

namespace ompl
{
    namespace base
    {
        IterationTerminationCondition::IterationTerminationCondition(unsigned int numIterations)
          : maxCalls_(numIterations),
            timesCalled_(0u)
        {
        }

        bool IterationTerminationCondition::eval()
        {
            ++timesCalled_;

            return (timesCalled_ > maxCalls_);
        }

        void IterationTerminationCondition::reset()
        {
            timesCalled_ = 0u;
        }

        IterationTerminationCondition::operator PlannerTerminationCondition()
        {
            return PlannerTerminationCondition( boost::bind(&IterationTerminationCondition::eval, this) );
        }
    }
}
