/**
 * @file llvolumemgr.cpp
 *
 * $LicenseInfo:firstyear=2002&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "linden_common.h"

#include "llmutex.h"
#include "llvolumemgr.h"
#include "llvolume.h"


const F32 BASE_THRESHOLD = 0.03f;

//static
F32 LLVolumeLODGroup::mDetailThresholds[NUM_LODS] = {BASE_THRESHOLD,
                                                     2*BASE_THRESHOLD,
                                                     8*BASE_THRESHOLD,
                                                     100*BASE_THRESHOLD};

//static
F32 LLVolumeLODGroup::mDetailScales[NUM_LODS] = {1.f, 1.5f, 2.5f, 4.f};


//============================================================================

LLVolumeMgr::LLVolumeMgr()
:   mDataMutex(NULL)
{
    // the LLMutex magic interferes with easy unit testing,
    // so you now must manually call useMutex() to use it
    //mDataMutex = new LLMutex();
}

LLVolumeMgr::~LLVolumeMgr()
{
    cleanup();

    delete mDataMutex;
    mDataMutex = NULL;
}

bool LLVolumeMgr::cleanup()
{
    bool no_refs = true;
    if (mDataMutex)
    {
        mDataMutex->lock();
    }
    for (volume_lod_group_map_t::iterator iter = mVolumeLODGroups.begin(),
             end = mVolumeLODGroups.end();
         iter != end; iter++)
    {
        LLVolumeLODGroup *volgroupp = iter->second;
        if (!volgroupp->cleanupRefs())
        {
            no_refs = false;
        }
        delete volgroupp;
    }
    mVolumeLODGroups.clear();
    if (mDataMutex)
    {
        mDataMutex->unlock();
    }
    return no_refs;
}

// Always only ever store the results of refVolume in a LLPointer
// Note however that LLVolumeLODGroup that contains the volume
//  also holds a LLPointer so the volume will only go away after
//  anything holding the volume and the LODGroup are destroyed
LLVolume* LLVolumeMgr::refVolume(const LLVolumeParams &volume_params, const S32 lod)
{
    LLVolumeLODGroup* volgroupp;
    if (mDataMutex)
    {
        mDataMutex->lock();
    }
    volume_lod_group_map_t::iterator iter = mVolumeLODGroups.find(&volume_params);
    if( iter == mVolumeLODGroups.end() )
    {
        volgroupp = createNewGroup(volume_params);
    }
    else
    {
        volgroupp = iter->second;
    }
    if (mDataMutex)
    {
        mDataMutex->unlock();
    }
    return volgroupp->refLOD(lod);
}

// virtual
LLVolumeLODGroup* LLVolumeMgr::getGroup( const LLVolumeParams& volume_params ) const
{
    LLVolumeLODGroup* volgroupp = NULL;
    if (mDataMutex)
    {
        mDataMutex->lock();
    }
    volume_lod_group_map_t::const_iterator iter = mVolumeLODGroups.find(&volume_params);
    if( iter != mVolumeLODGroups.end() )
    {
        volgroupp = iter->second;
    }
    if (mDataMutex)
    {
        mDataMutex->unlock();
    }
    return volgroupp;
}

void LLVolumeMgr::unrefVolume(LLVolume *volumep)
{
    if (volumep->isUnique())
    {
        // TomY: Don't need to manage this volume. It is a unique instance.
        return;
    }
    const LLVolumeParams* params = &(volumep->getParams());
    if (mDataMutex)
    {
        mDataMutex->lock();
    }
    volume_lod_group_map_t::iterator iter = mVolumeLODGroups.find(params);
    if( iter == mVolumeLODGroups.end() )
    {
        LL_ERRS() << "Warning! Tried to cleanup unknown volume type! " << *params << LL_ENDL;
        if (mDataMutex)
        {
            mDataMutex->unlock();
        }
        return;
    }
    else
    {
        LLVolumeLODGroup* volgroupp = iter->second;

        volgroupp->derefLOD(volumep);
        if (volgroupp->getNumRefs() == 0)
        {
            mVolumeLODGroups.erase(params);
            delete volgroupp;
        }
    }
    if (mDataMutex)
    {
        mDataMutex->unlock();
    }

}

// protected
void LLVolumeMgr::insertGroup(LLVolumeLODGroup* volgroup)
{
    mVolumeLODGroups[volgroup->getVolumeParams()] = volgroup;
}

// protected
LLVolumeLODGroup* LLVolumeMgr::createNewGroup(const LLVolumeParams& volume_params)
{
    LLVolumeLODGroup* volgroup = new LLVolumeLODGroup(volume_params);
    insertGroup(volgroup);
    return volgroup;
}

// virtual
void LLVolumeMgr::dump()
{
    F32 avg = 0.f;
    if (mDataMutex)
    {
        mDataMutex->lock();
    }
    for (volume_lod_group_map_t::iterator iter = mVolumeLODGroups.begin(),
             end = mVolumeLODGroups.end();
         iter != end; iter++)
    {
        LLVolumeLODGroup *volgroupp = iter->second;
        avg += volgroupp->dump();
    }
    int count = (int)mVolumeLODGroups.size();
    avg = count ? avg / (F32)count : 0.0f;
    if (mDataMutex)
    {
        mDataMutex->unlock();
    }
    LL_INFOS() << "Average usage of LODs " << avg << LL_ENDL;
}

void LLVolumeMgr::useMutex()
{
    if (!mDataMutex)
    {
        mDataMutex = new LLMutex();
    }
}

std::ostream& operator<<(std::ostream& s, const LLVolumeMgr& volume_mgr)
{
    s << "{ numLODgroups=" << volume_mgr.mVolumeLODGroups.size() << ", ";

    S32 total_refs = 0;
    if (volume_mgr.mDataMutex)
    {
        volume_mgr.mDataMutex->lock();
    }

    for (LLVolumeMgr::volume_lod_group_map_t::const_iterator iter = volume_mgr.mVolumeLODGroups.begin();
         iter != volume_mgr.mVolumeLODGroups.end(); ++iter)
    {
        LLVolumeLODGroup *volgroupp = iter->second;
        total_refs += volgroupp->getNumRefs();
        s << ", " << (*volgroupp);
    }

    if (volume_mgr.mDataMutex)
    {
        volume_mgr.mDataMutex->unlock();
    }

    s << ", total_refs=" << total_refs << " }";
    return s;
}

LLVolumeLODGroup::LLVolumeLODGroup(const LLVolumeParams &params)
    : mVolumeParams(params),
      mRefs(0)
{
    for (S32 i = 0; i < NUM_LODS; i++)
    {
        mLODRefs[i] = 0;
        mAccessCount[i] = 0;
    }
}

LLVolumeLODGroup::~LLVolumeLODGroup()
{
    for (S32 i = 0; i < NUM_LODS; i++)
    {
        llassert_always(mLODRefs[i] == 0);
    }
}

// Called from LLVolumeMgr::cleanup
bool LLVolumeLODGroup::cleanupRefs()
{
    bool res = true;
    if (mRefs != 0)
    {
        LL_WARNS() << "Volume group has remaining refs:" << getNumRefs() << LL_ENDL;
        mRefs = 0;
        for (S32 i = 0; i < NUM_LODS; i++)
        {
            if (mLODRefs[i] > 0)
            {
                LL_WARNS() << " LOD " << i << " refs = " << mLODRefs[i] << LL_ENDL;
                mLODRefs[i] = 0;
                mVolumeLODs[i] = NULL;
            }
        }
        LL_WARNS() << *getVolumeParams() << LL_ENDL;
        res = false;
    }
    return res;
}

LLVolume* LLVolumeLODGroup::refLOD(const S32 lod)
{
    llassert(lod >=0 && lod < NUM_LODS);
    mAccessCount[lod]++;

    mRefs++;
    if (mVolumeLODs[lod].isNull())
    {
        mVolumeLODs[lod] = new LLVolume(mVolumeParams, mDetailScales[lod]);
    }
    mLODRefs[lod]++;
    return mVolumeLODs[lod];
}

bool LLVolumeLODGroup::derefLOD(LLVolume *volumep)
{
    llassert_always(mRefs > 0);
    mRefs--;
    for (S32 i = 0; i < NUM_LODS; i++)
    {
        if (mVolumeLODs[i] == volumep)
        {
            llassert_always(mLODRefs[i] > 0);
            mLODRefs[i]--;
#if 0 // SJB: Possible opt: keep other lods around
            if (!mLODRefs[i])
            {
                mVolumeLODs[i] = NULL;
            }
#endif
            return true;
        }
    }
    LL_ERRS() << "Deref of non-matching LOD in volume LOD group" << LL_ENDL;
    return false;
}

S32 LLVolumeLODGroup::getDetailFromTan(const F32 tan_angle)
{
    S32 i = 0;
    while (i < (NUM_LODS - 1))
    {
        if (tan_angle <= mDetailThresholds[i])
        {
            return i;
        }
        i++;
    }
    return NUM_LODS - 1;
}

void LLVolumeLODGroup::getDetailProximity(const F32 tan_angle, F32 &to_lower, F32& to_higher)
{
    S32 detail = getDetailFromTan(tan_angle);

    if (detail > 0)
    {
        to_lower = tan_angle - mDetailThresholds[detail];
    }
    else
    {
        to_lower = 1024.f*1024.f;
    }

    if (detail < NUM_LODS-1)
    {
        to_higher = mDetailThresholds[detail+1] - tan_angle;
    }
    else
    {
        to_higher = 1024.f*1024.f;
    }
}

F32 LLVolumeLODGroup::getVolumeScaleFromDetail(const S32 detail)
{
    return mDetailScales[detail];
}

S32 LLVolumeLODGroup::getVolumeDetailFromScale(const F32 detail)
{
    for (S32 i = 1; i < 4; i++)
    {
        if (mDetailScales[i] > detail)
        {
            return i-1;
        }
    }

    return 3;
}

F32 LLVolumeLODGroup::dump()
{
    F32 usage = 0.f;
    for (S32 i = 0; i < NUM_LODS; i++)
    {
        if (mAccessCount[i] > 0)
        {
            usage += 1.f;
        }
    }
    usage = usage / (F32)NUM_LODS;

    std::string dump_str = llformat("%.3f %d %d %d %d", usage, mAccessCount[0], mAccessCount[1], mAccessCount[2], mAccessCount[3]);

    LL_INFOS() << dump_str << LL_ENDL;
    return usage;
}

std::ostream& operator<<(std::ostream& s, const LLVolumeLODGroup& volgroup)
{
    s << "{ numRefs=" << volgroup.getNumRefs();
    s << ", mParams=" << volgroup.getVolumeParams();
    s << " }";

    return s;
}