/*
    Copyright 2005-2014 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks. Threading Building Blocks is free software;
    you can redistribute it and/or modify it under the terms of the GNU General Public License
    version 2  as  published  by  the  Free Software Foundation.  Threading Building Blocks is
    distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
    implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See  the GNU General Public License for more details.   You should have received a copy of
    the  GNU General Public License along with Threading Building Blocks; if not, write to the
    Free Software Foundation, Inc.,  51 Franklin St,  Fifth Floor,  Boston,  MA 02110-1301 USA

    As a special exception,  you may use this file  as part of a free software library without
    restriction.  Specifically,  if other files instantiate templates  or use macros or inline
    functions from this file, or you compile this file and link it with other files to produce
    an executable,  this file does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however invalidate any other
    reasons why the executable file might be covered by the GNU General Public License.
*/

/*
    This file contains a few implementations, so it may look overly complicated.
    The most efficient implementation is also separated into convex_hull_sample.cpp
*/
#include "convex_hull.h"

typedef util::point<double> point_t;

#ifndef USETBB
    #define USETBB      1
#endif
#ifndef USECONCVEC
    #define USECONCVEC   1
#endif

#if !USETBB // Serial implementation of Quick Hull algorithm

typedef std::vector< point_t > pointVec_t;

void serial_initialize(pointVec_t &points);

// C++ style serial code

class FindXExtremum : public std::unary_function<const point_t&, void> {
public:
    typedef enum {
        minX, maxX
    } extremumType;

    FindXExtremum(const point_t& frstPoint, extremumType exType_)
        : extrXPoint(frstPoint), exType(exType_) {}

    void operator()(const point_t& p) {
        if(closerToExtremum(p))
            extrXPoint = p;
    }

    operator point_t () {
        return extrXPoint;
    }

private:
    const extremumType   exType;
    point_t              extrXPoint;

    bool closerToExtremum(const point_t &p) const {
        switch(exType) {
        case minX:
            return p.x<extrXPoint.x; break;
        case maxX:
            return p.x>extrXPoint.x; break;
        }
        return false; // avoid warning
    }
};

template <FindXExtremum::extremumType type>
point_t extremum(const pointVec_t &points) {
    assert(!points.empty());
    return std::for_each(points.begin(), points.end(), FindXExtremum(points[0], type));
}

class SplitByCP : public std::unary_function<const point_t&, void> {
    pointVec_t          &reducedSet;
    point_t              p1, p2;
    point_t              farPoint;
    double               howFar;
public:

    SplitByCP( point_t _p1, point_t _p2, pointVec_t &_reducedSet)
        : p1(_p1), p2(_p2), reducedSet(_reducedSet), howFar(0), farPoint(p1) {}

    void operator()(const point_t& p) {
        double cp;
        if( (p != p1) && (p != p2) ) {
            cp = util::cross_product(p1, p2, p);
            if(cp>0) {
                reducedSet.push_back(p);
                if(cp>howFar) {
                    farPoint = p;
                    howFar   = cp;
                }
            }
        }
    }

    operator point_t (){
        return farPoint;
    }
};

point_t divide(const pointVec_t &P, pointVec_t &P_reduced, const point_t &p1, const point_t &p2) {
    SplitByCP splitByCP(p1, p2, P_reduced);
    point_t farPoint = std::for_each(P.begin(), P.end(), splitByCP);

    if(util::verbose) {
        std::stringstream ss;
        ss << P.size() << " nodes in bucket"<< ", "
            << "dividing by: [ " << p1 << ", " << p2 << " ], "
            << "farthest node: " << farPoint;
        util::OUTPUT.push_back(ss.str());
    }

    return farPoint;
}

void divide_and_conquer(const pointVec_t &P, pointVec_t &H, point_t p1, point_t p2) {
    assert(P.size() >= 2);
    pointVec_t P_reduced;
    pointVec_t H1, H2;
    point_t p_far = divide(P, P_reduced, p1, p2);
    if (P_reduced.size()<2) {
        H.push_back(p1);
        H.insert(H.end(), P_reduced.begin(), P_reduced.end());
    }
    else {
        divide_and_conquer(P_reduced, H1, p1, p_far);
        divide_and_conquer(P_reduced, H2, p_far, p2);

        H.insert(H.end(), H1.begin(), H1.end());
        H.insert(H.end(), H2.begin(), H2.end());
    }
}

void quickhull(const pointVec_t &points, pointVec_t &hull) {
    if (points.size() < 2) {
        hull.insert(hull.end(), points.begin(), points.end());
        return;
    }
    point_t p_maxx = extremum<FindXExtremum::maxX>(points);
    point_t p_minx = extremum<FindXExtremum::minX>(points);

    pointVec_t H;

    divide_and_conquer(points, hull, p_maxx, p_minx);
    divide_and_conquer(points, H, p_minx, p_maxx);
    hull.insert(hull.end(), H.begin(), H.end());
}


int main(int argc, char* argv[]) {
    util::ParseInputArgs(argc, argv);

    pointVec_t      points;
    pointVec_t      hull;
    util::my_time_t tm_init, tm_start, tm_end;

    std::cout << "Starting serial version of QUICK HULL algorithm" << std::endl;

    tm_init = util::gettime();
    serial_initialize(points);
    tm_start = util::gettime();
    std::cout << "Init time: " << util::time_diff(tm_init, tm_start) << "  Points in input: " << points.size() << "\n";
    tm_start = util::gettime();
    quickhull(points, hull);
    tm_end = util::gettime();
    std::cout << "Serial time: " << util::time_diff(tm_start, tm_end) << "  Points in hull: " << hull.size() << "\n";
}

#else // USETBB - parallel version of Quick Hull algorithm

#include "tbb/task_scheduler_init.h"
#include "tbb/parallel_for.h"
#include "tbb/parallel_reduce.h"
#include "tbb/blocked_range.h"

typedef tbb::blocked_range<size_t> range_t;

#if USECONCVEC
#include "tbb/concurrent_vector.h"

typedef tbb::concurrent_vector<point_t> pointVec_t;

void appendVector(const point_t* src, size_t srcSize, pointVec_t& dest) {
    std::copy(src, src + srcSize, dest.grow_by(srcSize));
}

void appendVector(const pointVec_t& src, pointVec_t& dest) {
    std::copy(src.begin(), src.end(), dest.grow_by(src.size()));
}

void grow_vector_to_at_least(pointVec_t& vect, size_t size) {
    vect.grow_to_at_least(size);
}
#else // USE STD::VECTOR - include spin_mutex.h and lock vector operations
#include "tbb/spin_mutex.h"

typedef tbb::spin_mutex      mutex_t;
typedef std::vector<point_t> pointVec_t;

void appendVector(mutex_t& insertMutex, const pointVec_t& src, pointVec_t& dest) {
    mutex_t::scoped_lock lock(insertMutex);
    dest.insert(dest.end(), src.begin(), src.end());
}

void appendVector(mutex_t& insertMutex, const point_t* src, size_t srcSize,
                  pointVec_t& dest) {
    mutex_t::scoped_lock lock(insertMutex);
    dest.insert(dest.end(), src, src + srcSize);
}

void grow_vector_to_at_least(mutex_t& mutex, pointVec_t& vect, size_t size) {
    mutex_t::scoped_lock lock(mutex);
    if (vect.size()< size){
        vect.resize(size);
    }
}
#endif // USECONCVEC

class FillRNDPointsVector {
    pointVec_t          &points;
public:
    static const size_t  grainSize = cfg::generateGrainSize;
#if !USECONCVEC
    static mutex_t       pushBackMutex;
#endif // USECONCVEC

    explicit FillRNDPointsVector(pointVec_t& _points)
        : points(_points){}

    void operator()(const range_t& range) const {
        util::rng the_rng(range.begin());
        const size_t i_end = range.end();
        size_t count = 0;
#if USECONCVEC
            points.grow_to_at_least(i_end);
#else // Locked enlarge to a not thread-safe STD::VECTOR
            grow_vector_to_at_least(pushBackMutex,points,i_end);
#endif // USECONCVEC

        for(size_t i = range.begin(); i != i_end; ++i) {
            points[i]=util::GenerateRNDPoint<double>(count,the_rng,util::rng::max_rand);
        }
    }
};

class FillRNDPointsVector_buf {
    pointVec_t          &points;
public:
    static const size_t  grainSize = cfg::generateGrainSize;
#if !USECONCVEC
    static mutex_t       insertMutex;
#endif // USECONCVEC

    explicit FillRNDPointsVector_buf(pointVec_t& _points)
        : points(_points){}

    void operator()(const range_t& range) const {
        util::rng the_rng(range.begin());
        const size_t i_end = range.end();
        size_t count = 0, j = 0;
        point_t tmp_vec[grainSize];

        for(size_t i=range.begin(); i!=i_end; ++i) {
            tmp_vec[j++] = util::GenerateRNDPoint<double>(count,the_rng,util::rng::max_rand);
        }
#if USECONCVEC
        grow_vector_to_at_least(points,range.end());
#else // USE STD::VECTOR
        grow_vector_to_at_least(insertMutex,points,range.end());
#endif // USECONCVEC
        std::copy(tmp_vec, tmp_vec+j,points.begin()+range.begin());
    }   
};

#if !USECONCVEC
mutex_t FillRNDPointsVector::pushBackMutex   = mutex_t();
mutex_t FillRNDPointsVector_buf::insertMutex = mutex_t();
#endif

template<typename BodyType>
void initialize(pointVec_t &points) {
    //This function generate the same series of point on every call.
    //Reproducibility is needed for benchmarking to produce reliable results.
    //It is achieved through the following points:
    //      - FillRNDPointsVector_buf instance has its own local instance
    //        of random number generator, which in turn does not use any global data
    //      - tbb::simple_partitioner produce the same set of ranges on every call to
    //        tbb::parallel_for
    //      - local RNG instances are seeded by the starting indexes of corresponding ranges
    //      - grow_to_at_least() enables putting points into the resulting vector in deterministic order
    //        (unlike concurrent push_back or grow_by).

    // In the buffered version, a temporary storage for as much as grainSize elements 
    // is allocated inside the body. Since auto_partitioner may increase effective
    // range size which would cause a crash, simple partitioner has to be used.

    tbb::parallel_for(range_t(0, cfg::numberOfPoints, BodyType::grainSize),
    BodyType(points), tbb::simple_partitioner());
}

class FindXExtremum {
public:
    typedef enum {
        minX, maxX
    } extremumType;

    static const size_t  grainSize = cfg::findExtremumGrainSize;

    FindXExtremum(const pointVec_t& points_, extremumType exType_)
        : points(points_), exType(exType_), extrXPoint(points[0]) {}

    FindXExtremum(const FindXExtremum& fxex, tbb::split)
        : points(fxex.points), exType(fxex.exType), extrXPoint(fxex.extrXPoint) {}

    void operator()(const range_t& range) {
        const size_t i_end = range.end();
        if(!range.empty()) {
            for(size_t i = range.begin(); i != i_end; ++i) {
                if(closerToExtremum(points[i])) {
                    extrXPoint = points[i];
                }
            }
        }
    }

    void join(const FindXExtremum &rhs) {
        if(closerToExtremum(rhs.extrXPoint)) {
            extrXPoint = rhs.extrXPoint;
        }
    }

    point_t extremeXPoint() {
        return extrXPoint;
    }

private:
    const pointVec_t    &points;
    const extremumType   exType;
    point_t              extrXPoint;
    bool closerToExtremum(const point_t &p) const {
        switch(exType) {
        case minX:
            return p.x<extrXPoint.x; break;
        case maxX:
            return p.x>extrXPoint.x; break;
        }
        return false; // avoid warning
    }
};

template <FindXExtremum::extremumType type>
point_t extremum(const pointVec_t &P) {
    FindXExtremum fxBody(P, type);
    tbb::parallel_reduce(range_t(0, P.size(), FindXExtremum::grainSize), fxBody);
    return fxBody.extremeXPoint();
}

class SplitByCP {
    const pointVec_t    &initialSet;
    pointVec_t          &reducedSet;
    point_t              p1, p2;
    point_t              farPoint;
    double               howFar;
public:
    static const size_t grainSize = cfg::divideGrainSize;
#if !USECONCVEC
    static mutex_t      pushBackMutex;
#endif // USECONCVEC

    SplitByCP( point_t _p1, point_t _p2,
        const pointVec_t &_initialSet, pointVec_t &_reducedSet)
        : p1(_p1), p2(_p2),
        initialSet(_initialSet), reducedSet(_reducedSet),
        howFar(0), farPoint(p1) {
    }

    SplitByCP( SplitByCP& sbcp, tbb::split )
        : p1(sbcp.p1), p2(sbcp.p2),
        initialSet(sbcp.initialSet), reducedSet(sbcp.reducedSet),
        howFar(0), farPoint(p1) {}

    void operator()( const range_t& range ) {
        const size_t i_end = range.end();
        double cp;
        for(size_t i=range.begin(); i!=i_end; ++i) {
            if( (initialSet[i] != p1) && (initialSet[i] != p2) ) {
                cp = util::cross_product(p1, p2, initialSet[i]);
                if(cp>0) {
#if USECONCVEC
                    reducedSet.push_back(initialSet[i]);
#else // Locked push_back to a not thread-safe STD::VECTOR
                    {
                        mutex_t::scoped_lock lock(pushBackMutex);
                        reducedSet.push_back(initialSet[i]);
                    }
#endif // USECONCVEC
                    if(cp>howFar) {
                        farPoint = initialSet[i];
                        howFar   = cp;
                    }
                }
            }
        }
    }

    void join(const SplitByCP& rhs) {
        if(rhs.howFar>howFar) {
            howFar   = rhs.howFar;
            farPoint = rhs.farPoint;
        }
    }

    point_t farthestPoint() const {
        return farPoint;
    }
};

class SplitByCP_buf {
    const pointVec_t    &initialSet;
    pointVec_t          &reducedSet;
    point_t              p1, p2;
    point_t              farPoint;
    double               howFar;
public:
    static const size_t  grainSize = cfg::divideGrainSize;
#if !USECONCVEC
    static mutex_t       insertMutex;
#endif // USECONCVEC

    SplitByCP_buf( point_t _p1, point_t _p2,
        const pointVec_t &_initialSet, pointVec_t &_reducedSet)
        : p1(_p1), p2(_p2),
        initialSet(_initialSet), reducedSet(_reducedSet),
        howFar(0), farPoint(p1) {}

    SplitByCP_buf(SplitByCP_buf& sbcp, tbb::split)
        : p1(sbcp.p1), p2(sbcp.p2),
        initialSet(sbcp.initialSet), reducedSet(sbcp.reducedSet),
        howFar(0), farPoint(p1) {}

    void operator()(const range_t& range) {
        const size_t i_end = range.end();
        size_t j = 0;
        double cp;
        point_t tmp_vec[grainSize];
        for(size_t i = range.begin(); i != i_end; ++i) {
            if( (initialSet[i] != p1) && (initialSet[i] != p2) ) {            
                cp = util::cross_product(p1, p2, initialSet[i]);
                if(cp>0) {
                    tmp_vec[j++] = initialSet[i];
                    if(cp>howFar) {
                        farPoint = initialSet[i];
                        howFar   = cp;
                    }
                }
            }
        }

#if USECONCVEC
        appendVector(tmp_vec, j, reducedSet);
#else // USE STD::VECTOR
        appendVector(insertMutex, tmp_vec, j, reducedSet);
#endif // USECONCVEC
    }

    void join(const SplitByCP_buf& rhs) {
        if(rhs.howFar>howFar) {
            howFar   = rhs.howFar;
            farPoint = rhs.farPoint;
        }
    }

    point_t farthestPoint() const {
        return farPoint;
    }
};

#if !USECONCVEC
mutex_t SplitByCP::pushBackMutex   = mutex_t();
mutex_t SplitByCP_buf::insertMutex = mutex_t();
#endif

template <typename BodyType>
point_t divide(const pointVec_t &P, pointVec_t &P_reduced,
              const point_t &p1, const point_t &p2) {
    BodyType body(p1, p2, P, P_reduced);
    // Must use simple_partitioner (see the comment in initialize() above)
    tbb::parallel_reduce(range_t(0, P.size(), BodyType::grainSize),
                         body, tbb::simple_partitioner() );

    if(util::verbose) {
        std::stringstream ss;
        ss << P.size() << " nodes in bucket"<< ", "
            << "dividing by: [ " << p1 << ", " << p2 << " ], "
            << "farthest node: " << body.farthestPoint();
        util::OUTPUT.push_back(ss.str());
    }

    return body.farthestPoint();
}

void divide_and_conquer(const pointVec_t &P, pointVec_t &H,
                        point_t p1, point_t p2, bool buffered) {
    assert(P.size() >= 2);
    pointVec_t P_reduced;
    pointVec_t H1, H2;
    point_t p_far;
    
    if(buffered) {
        p_far = divide<SplitByCP_buf>(P, P_reduced, p1, p2);
    } else {
        p_far = divide<SplitByCP>(P, P_reduced, p1, p2);
    }

    if (P_reduced.size()<2) {
        H.push_back(p1);
#if USECONCVEC
        appendVector(P_reduced, H);
#else // insert into STD::VECTOR
        H.insert(H.end(), P_reduced.begin(), P_reduced.end());
#endif
    }
    else {
        divide_and_conquer(P_reduced, H1, p1, p_far, buffered);
        divide_and_conquer(P_reduced, H2, p_far, p2, buffered);

#if USECONCVEC
        appendVector(H1, H);
        appendVector(H2, H);
#else // insert into STD::VECTOR
        H.insert(H.end(), H1.begin(), H1.end());
        H.insert(H.end(), H2.begin(), H2.end());
#endif
    }
}

void quickhull(const pointVec_t &points, pointVec_t &hull, bool buffered) {
    if (points.size() < 2) {
#if USECONCVEC
        appendVector(points, hull);
#else // STD::VECTOR
        hull.insert(hull.end(), points.begin(), points.end());
#endif // USECONCVEC
        return;
    }

    point_t p_maxx = extremum<FindXExtremum::maxX>(points);
    point_t p_minx = extremum<FindXExtremum::minX>(points);

    pointVec_t H;

    divide_and_conquer(points, hull, p_maxx, p_minx, buffered);
    divide_and_conquer(points, H, p_minx, p_maxx, buffered);
#if USECONCVEC
    appendVector(H, hull);
#else // STD::VECTOR
    hull.insert(hull.end(), H.begin(), H.end());
#endif // USECONCVEC
}

int main(int argc, char* argv[]) {
    util::ParseInputArgs(argc, argv);

    int             nthreads;
    util::my_time_t tm_init, tm_start, tm_end;

#if USECONCVEC
    std::cout << "Starting TBB unbuffered push_back version of QUICK HULL algorithm" << std::endl;
#else
    std::cout << "Starting STL locked unbuffered push_back version of QUICK HULL algorithm" << std::endl;
#endif // USECONCVEC

    for(nthreads=cfg::threads.first; nthreads<=cfg::threads.last; nthreads=cfg::threads.step(nthreads)) {
        pointVec_t      points;
        pointVec_t      hull;

        tbb::task_scheduler_init init(nthreads);
        tm_init = util::gettime();
        initialize<FillRNDPointsVector>(points);
        tm_start = util::gettime();
        std::cout << "Parallel init time on " << nthreads << " threads: " << util::time_diff(tm_init, tm_start) << "  Points in input: " << points.size() << "\n";

        tm_start = util::gettime();
        quickhull(points, hull, false);
        tm_end = util::gettime();
        std::cout << "Time on " << nthreads << " threads: " << util::time_diff(tm_start, tm_end) << "  Points in hull: " << hull.size() << "\n";
    }

#if USECONCVEC 
    std::cout << "Starting TBB buffered version of QUICK HULL algorithm" << std::endl;
#else
    std::cout << "Starting STL locked buffered version of QUICK HULL algorithm" << std::endl;
#endif

    for(nthreads=cfg::threads.first; nthreads<=cfg::threads.last; nthreads=cfg::threads.step(nthreads)) {
        pointVec_t      points;
        pointVec_t      hull;

        tbb::task_scheduler_init init(nthreads);

        tm_init = util::gettime();
        initialize<FillRNDPointsVector_buf>(points);
        tm_start = util::gettime();
        std::cout << "Init time on " << nthreads << " threads: " << util::time_diff(tm_init, tm_start) << "  Points in input: " << points.size() << "\n";

        tm_start = util::gettime();
        quickhull(points, hull, true);
        tm_end = util::gettime();
        std::cout << "Time on " << nthreads << " threads: " << util::time_diff(tm_start, tm_end) << "  Points in hull: " << hull.size() << "\n";
    }    

    return 0;
}

#endif // USETBB

void serial_initialize(pointVec_t &points) {
    points.reserve(cfg::numberOfPoints);

    unsigned int rseed=1;
    for(size_t i=0, count=0; long(i)<cfg::numberOfPoints; ++i) {
        points.push_back(util::GenerateRNDPoint<double>(count,&std::rand,RAND_MAX ));
    }
}
