/*

Copyright (c) 2015, M. Kerber, D. Morozov, A. Nigmetov
All rights reserved.

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*/

#ifndef HERA_NEIGHB_ORACLE_H
#define HERA_NEIGHB_ORACLE_H

#include <unordered_map>
#include <algorithm>
#include <memory>

#include "basic_defs_bt.h"
#include "dnn/geometry/euclidean-fixed.h"
#include "dnn/local/kd-tree.h"



namespace hera {
namespace bt {

template<class Real>
class NeighbOracleSimple
{
public:
    using DgmPoint = DiagramPoint<Real>;
    using DgmPointSet = DiagramPointSet<Real>;

private:
    Real r;
    Real distEpsilon;
    DgmPointSet pointSet;

public:

    NeighbOracleSimple() : r(0.0) {}

    NeighbOracleSimple(const DgmPointSet& _pointSet, const Real _r, const Real _distEpsilon) :
        r(_r),
        distEpsilon(_distEpsilon),
        pointSet(_pointSet)
    {}

    void deletePoint(const DgmPoint& p)
    {
        pointSet.erase(p);
    }

    void rebuild(const DgmPointSet& S, const double rr)
    {
        pointSet = S;
        r = rr;
    }

    bool getNeighbour(const DgmPoint& q, DgmPoint& result) const
    {
        for(auto pit = pointSet.cbegin(); pit != pointSet.cend(); ++pit) {
            if ( distLInf(*pit, q) <= r) {
                result = *pit;
                return true;
            }
        }
        return false;
    }

    void getAllNeighbours(const DgmPoint& q, std::vector<DgmPoint>& result)
    {
        result.clear();
        for(const auto& point : pointSet) {
            if ( distLInf(point, q) <= r) {
                result.push_back(point);
            }
        }
        for(auto& pt : result) {
            deletePoint(pt);
        }
    }

};

template<class Real_>
class NeighbOracleDnn
{
public:

    using Real = Real_;
    using DnnPoint = dnn::Point<2, double>;
    using DnnTraits = dnn::PointTraits<DnnPoint>;
    using DgmPoint = DiagramPoint<Real>;
    using DgmPointSet = DiagramPointSet<Real>;
    using DgmPointHash = DiagramPointHash<Real>;

    Real r;
    Real distEpsilon;
    std::vector<DgmPoint> allPoints;
    DgmPointSet diagonalPoints;
    std::unordered_map<DgmPoint, size_t, DgmPointHash> pointIdxLookup;
    // dnn-stuff
    std::unique_ptr<dnn::KDTree<DnnTraits>> kdtree;
    std::vector<DnnPoint> dnnPoints;
    std::vector<DnnPoint*> dnnPointHandles;
    std::vector<size_t> kdtreeItems;

    NeighbOracleDnn(const DgmPointSet& S, const Real rr, const Real dEps) :
        kdtree(nullptr)
    {
        assert(dEps >= 0);
        distEpsilon = dEps;
        rebuild(S, rr);
    }


    void deletePoint(const DgmPoint& p)
    {
        auto findRes = pointIdxLookup.find(p);
        assert(findRes != pointIdxLookup.end());
        //std::cout <<  "Deleting point " <<  p << std::endl;
        size_t pointIdx { (*findRes).second };
        //std::cout <<  "pointIdx =  " << pointIdx << std::endl;
        diagonalPoints.erase(p, false);
        kdtree->delete_point(dnnPointHandles[kdtreeItems[pointIdx]]);
    }

    void rebuild(const DgmPointSet& S, const Real rr)
    {
        //std::cout <<  "Entered rebuild, r = " <<  rr << std::endl;
        r = rr;
        size_t dnnNumPoints = S.size();
        //printDebug(isDebug, "S = ", S);
        if (dnnNumPoints  > 0) {
            pointIdxLookup.clear();
            pointIdxLookup.reserve(S.size());
            allPoints.clear();
            allPoints.reserve(S.size());
            diagonalPoints.clear();
            diagonalPoints.reserve(S.size() / 2);
            for(auto pit = S.cbegin(); pit != S.cend(); ++pit) {
                allPoints.push_back(*pit);
                if (pit->isDiagonal()) {
                    diagonalPoints.insert(*pit);
                }
            }

            size_t pointIdx = 0;
            for(auto& dataPoint : allPoints) {
                pointIdxLookup.insert( { dataPoint, pointIdx++ } );
            }

            size_t dnnItemIdx { 0 };
            size_t trueIdx { 0 };
            dnnPoints.clear();
            kdtreeItems.clear();
            dnnPointHandles.clear();
            dnnPoints.clear();
            kdtreeItems.reserve(S.size() );
            // store normal items in kd-tree
            for(const auto& g : allPoints) {
                if (true) {
                    kdtreeItems.push_back(dnnItemIdx);
                    // index of items is id of dnn-point
                    DnnPoint p(trueIdx);
                    p[0] = g.getRealX();
                    p[1] = g.getRealY();
                    dnnPoints.push_back(p);
                    assert(dnnItemIdx == dnnPoints.size() - 1);
                    dnnItemIdx++;
                }
                trueIdx++;
            }
            assert(dnnPoints.size() == allPoints.size() );
            for(size_t i = 0; i < dnnPoints.size(); ++i) {
                dnnPointHandles.push_back(&dnnPoints[i]);
            }
            DnnTraits traits;
            //std::cout << "kdtree: " << dnnPointHandles.size() << " points" << std::endl;
            kdtree.reset(new dnn::KDTree<DnnTraits>(traits, dnnPointHandles));
        }
    }


    bool getNeighbour(const DgmPoint& q, DgmPoint& result) const
    {
        //std::cout << "getNeighbour for q = " << q << ", r = " << r << std::endl;
        //std::cout << *this << std::endl;
        // distance between two diagonal points
        // is  0
        if (q.isDiagonal()) {
            if (!diagonalPoints.empty()) {
                result = *diagonalPoints.cbegin();
                //std::cout <<  "Neighbour found in diagonal points, res =  " <<  result;
                return true;
            }
        }
        // check if kdtree is not empty
        if (0 == kdtree->get_num_points() ) {
            //std::cout << "empty tree, no neighb." << std::endl;
            return false;
        }
        // if no neighbour found among diagonal points,
        // search in kd_tree
        DnnPoint queryPoint;
        queryPoint[0] = q.getRealX();
        queryPoint[1] = q.getRealY();
        auto kdtreeResult = kdtree->findFirstR(queryPoint, r);
        if (kdtreeResult.empty()) {
            //std::cout << "no neighbour within " << r << "found." << std::endl;
            return false;
        }
        if (kdtreeResult[0].d <= r + distEpsilon) {
            result = allPoints[kdtreeResult[0].p->id()];
            //std::cout << "Neighbour found with kd-tree, index =  " << kdtreeResult[0].p->id() << std::endl;
            //std::cout << "result =  " <<  result << std::endl;
            return true;
        }
        //std::cout << "No neighbour found for r =  " << r << std::endl;
        return false;
    }



    void getAllNeighbours(const DgmPoint& q, std::vector<DgmPoint>& result)
    {
        //std::cout <<  "Entered getAllNeighbours for q = " << q << std::endl;
        result.clear();
        // add diagonal points, if necessary
        if (  q.isDiagonal() ) {
            for( auto& diagPt : diagonalPoints ) {
                result.push_back(diagPt);
            }
        }
        // delete diagonal points we found
        // to prevent finding them again
        for(auto& pt : result) {
            //std::cout << "deleting DIAG point pt = " << pt << std::endl;
            deletePoint(pt);
        }
        size_t diagOffset = result.size();
        std::vector<size_t> pointIndicesOut;
        // perorm range search on kd-tree
        DnnPoint queryPoint;
        queryPoint[0] = q.getRealX();
        queryPoint[1] = q.getRealY();
        auto kdtreeResult = kdtree->findR(queryPoint, r);
        pointIndicesOut.reserve(kdtreeResult.size());
        for(auto& handleDist : kdtreeResult) {
            if (handleDist.d <= r + distEpsilon) {
                pointIndicesOut.push_back(handleDist.p->id());
            } else {
                break;
            }
        }
        // get actual points in result
        for(auto& ptIdx : pointIndicesOut) {
            result.push_back(allPoints[ptIdx]);
        }
        // delete all points we found
        for(auto ptIt = result.begin() + diagOffset; ptIt != result.end(); ++ptIt) {
            //printDebug(isDebug, "deleting point pt = ", *ptIt);
            deletePoint(*ptIt);
        }
    }

    //DgmPointSet originalPointSet;
    template<class R>
    friend std::ostream& operator<<(std::ostream& out, const NeighbOracleDnn<R>& oracle);

};

} // end namespace bt
} // end namespace hera

#endif // HERA_NEIGHB_ORACLE_H