/*
 * Copyright (C) 2016+     AzerothCore <www.azerothcore.org>, released under GNU GPL v2 license, you may redistribute it and/or modify it under version 2 of the License, or (at your option), any later version.
 * Copyright (C) 2008-2016 TrinityCore <http://www.trinitycore.org/>
 * Copyright (C) 2005-2009 MaNGOS <http://getmangos.com/>
 */

#include "DynamicTree.h"
#include "BoundingIntervalHierarchyWrapper.h"
#include "GameObjectModel.h"
#include "Log.h"
#include "ModelInstance.h"
#include "RegularGrid.h"
#include "Timer.h"
#include <G3D/AABox.h>
#include <G3D/Ray.h>
#include <G3D/Vector3.h>

using VMAP::ModelInstance;

namespace
{
    int CHECK_TREE_PERIOD = 200;
}

template<> struct HashTrait< GameObjectModel>
{
    static size_t hashCode(const GameObjectModel& g) { return (size_t)(void*)&g; }
};

template<> struct PositionTrait< GameObjectModel>
{
    static void GetPosition(const GameObjectModel& g, G3D::Vector3& p) { p = g.GetPosition(); }
};

template<> struct BoundsTrait< GameObjectModel>
{
    static void GetBounds(const GameObjectModel& g, G3D::AABox& out) { out = g.GetBounds();}
    static void GetBounds2(const GameObjectModel* g, G3D::AABox& out) { out = g->GetBounds();}
};

typedef RegularGrid2D<GameObjectModel, BIHWrap<GameObjectModel>> ParentTree;

struct DynTreeImpl : public ParentTree
{
    typedef GameObjectModel Model;
    typedef ParentTree base;

    DynTreeImpl() :
        rebalance_timer(CHECK_TREE_PERIOD),
        unbalanced_times(0)
    {
    }

    void insert(const Model& mdl)
    {
        base::insert(mdl);
        ++unbalanced_times;
    }

    void remove(const Model& mdl)
    {
        base::remove(mdl);
        ++unbalanced_times;
    }

    void balance()
    {
        base::balance();
        unbalanced_times = 0;
    }

    void update(uint32 difftime)
    {
        if (!size())
        {
            return;
        }

        rebalance_timer.Update(difftime);
        if (rebalance_timer.Passed())
        {
            rebalance_timer.Reset(CHECK_TREE_PERIOD);
            if (unbalanced_times > 0)
            {
                balance();
            }
        }
    }

    TimeTrackerSmall rebalance_timer;
    int unbalanced_times;
};

DynamicMapTree::DynamicMapTree() : impl(new DynTreeImpl()) { }

DynamicMapTree::~DynamicMapTree()
{
    delete impl;
}

void DynamicMapTree::insert(const GameObjectModel& mdl)
{
    impl->insert(mdl);
}

void DynamicMapTree::remove(const GameObjectModel& mdl)
{
    impl->remove(mdl);
}

bool DynamicMapTree::contains(const GameObjectModel& mdl) const
{
    return impl->contains(mdl);
}

void DynamicMapTree::balance()
{
    impl->balance();
}

int DynamicMapTree::size() const
{
    return impl->size();
}

void DynamicMapTree::update(uint32 t_diff)
{
    impl->update(t_diff);
}

struct DynamicTreeIntersectionCallback
{
    bool did_hit;
    uint32 phase_mask;
    DynamicTreeIntersectionCallback(uint32 phasemask) : did_hit(false), phase_mask(phasemask) { }
    bool operator()(const G3D::Ray& r, const GameObjectModel& obj, float& distance, bool stopAtFirstHit)
    {
        bool result = obj.intersectRay(r, distance, stopAtFirstHit, phase_mask);
        if (result)
        {
            did_hit = result;
        }
        return result;
    }
    bool didHit() const { return did_hit;}
};

bool DynamicMapTree::GetIntersectionTime(const uint32 phasemask, const G3D::Ray& ray,
        const G3D::Vector3& endPos, float& maxDist) const
{
    float distance = maxDist;
    DynamicTreeIntersectionCallback callback(phasemask);
    impl->intersectRay(ray, callback, distance, endPos, false);
    if (callback.didHit())
    {
        maxDist = distance;
    }
    return callback.didHit();
}

bool DynamicMapTree::GetObjectHitPos(const uint32 phasemask, const G3D::Vector3& startPos,
                                     const G3D::Vector3& endPos, G3D::Vector3& resultHit,
                                     float modifyDist) const
{
    bool result = false;
    float maxDist = (endPos - startPos).magnitude();
    // valid map coords should *never ever* produce float overflow, but this would produce NaNs too
    ASSERT(maxDist < std::numeric_limits<float>::max());
    // prevent NaN values which can cause BIH intersection to enter infinite loop
    if (maxDist < 1e-10f)
    {
        resultHit = endPos;
        return false;
    }
    G3D::Vector3 dir = (endPos - startPos) / maxDist;            // direction with length of 1
    G3D::Ray ray(startPos, dir);
    float dist = maxDist;
    if (GetIntersectionTime(phasemask, ray, endPos, dist))
    {
        resultHit = startPos + dir * dist;
        if (modifyDist < 0)
        {
            if ((resultHit - startPos).magnitude() > -modifyDist)
            {
                resultHit = resultHit + dir * modifyDist;
            }
            else
            {
                resultHit = startPos;
            }
        }
        else
        {
            resultHit = resultHit + dir * modifyDist;
        }

        result = true;
    }
    else
    {
        resultHit = endPos;
        result = false;
    }
    return result;
}

bool DynamicMapTree::isInLineOfSight(float x1, float y1, float z1, float x2, float y2, float z2, uint32 phasemask) const
{
    G3D::Vector3 v1(x1, y1, z1), v2(x2, y2, z2);

    float maxDist = (v2 - v1).magnitude();

    if (!G3D::fuzzyGt(maxDist, 0) )
    {
        return true;
    }

    G3D::Ray r(v1, (v2 - v1) / maxDist);
    DynamicTreeIntersectionCallback callback(phasemask);
    impl->intersectRay(r, callback, maxDist, v2, true);

    return !callback.did_hit;
}

float DynamicMapTree::getHeight(float x, float y, float z, float maxSearchDist, uint32 phasemask) const
{
    G3D::Vector3 v(x, y, z);
    G3D::Ray r(v, G3D::Vector3(0, 0, -1));
    DynamicTreeIntersectionCallback callback(phasemask);
    impl->intersectZAllignedRay(r, callback, maxSearchDist);

    if (callback.didHit())
    {
        return v.z - maxSearchDist;
    }
    else
    {
        return -G3D::finf();
    }
}