/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2024 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM 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 OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

\*---------------------------------------------------------------------------*/

#include "cellMapper.H"
#include "polyMesh.H"
#include "mapPolyMesh.H"

// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //

void Foam::cellMapper::calcAddressing() const
{
    if
    (
        directAddrPtr_
     || interpAddrPtr_
     || weightsPtr_
     || insertedObjectsPtr_
    )
    {
        FatalErrorInFunction
            << "Addressing already calculated."
            << abort(FatalError);
    }

    if (direct())
    {
        // Direct addressing, no weights

        directAddrPtr_ = std::make_unique<labelList>
        (
            // No retired cells, so cellMap().size() == mapperLen_ anyhow
            labelList::subList(mpm_.cellMap(), mapperLen_)
        );
        auto& directAddr = *directAddrPtr_;

        insertedObjectsPtr_ = std::make_unique<labelList>();
        auto& inserted = *insertedObjectsPtr_;

        // The nInsertedObjects_ already counted in the constructor
        if (nInsertedObjects_)
        {
            inserted.resize(nInsertedObjects_);

            label nInserted = 0;
            forAll(directAddr, i)
            {
                if (directAddr[i] < 0)
                {
                    // Found inserted
                    directAddr[i] = 0;
                    inserted[nInserted] = i;
                    ++nInserted;

                    // TBD: check (nInsertedObjects_ < nInserted)?
                    #ifdef FULLDEBUG
                    if (nInsertedObjects_ < nInserted)
                    {
                        FatalErrorInFunction
                            << "Unexpected insert of more than "
                            << nInsertedObjects_ << " items\n"
                            << abort(FatalError);
                    }
                    #endif
                }
            }
            // TBD: check (nInserted < nInsertedObjects_)?
            #ifdef FULLDEBUG
            if (nInserted < nInsertedObjects_)
            {
                WarningInFunction
                    << "Found " << nInserted << " instead of "
                    << nInsertedObjects_ << " items to insert\n";
            }
            #endif
            // The resize should be unnecessary
            inserted.resize(nInserted);
        }
    }
    else
    {
        // Interpolative addressing

        interpAddrPtr_ = std::make_unique<labelListList>(mapperLen_);
        auto& addr = *interpAddrPtr_;

        weightsPtr_ = std::make_unique<scalarListList>(mapperLen_);
        auto& wght = *weightsPtr_;


        // Set the addressing and uniform weight
        const auto setAddrWeights = [&]
        (
            const List<objectMap>& maps,
            const char * const nameOfMap
        )
        {
            for (const objectMap& map : maps)
            {
                // Get index, addressing
                const label celli = map.index();
                const labelList& mo = map.masterObjects();
                if (mo.empty()) continue;  // safety

                if (addr[celli].size())
                {
                    FatalErrorInFunction
                        << "Master cell " << celli
                        << " already mapped, cannot apply "
                        << nameOfMap
                        << flatOutput(mo) << abort(FatalError);
                }

                // Map from masters, uniform weights
                addr[celli] = mo;
                wght[celli] = scalarList(mo.size(), 1.0/mo.size());
            }
        };


        setAddrWeights(mpm_.cellsFromPointsMap(), "point cells");
        setAddrWeights(mpm_.cellsFromEdgesMap(), "edge cells");
        setAddrWeights(mpm_.cellsFromFacesMap(), "face cells");

        // Volume conservative mapping if possible

        const List<objectMap>& cellsFromCells = mpm_.cellsFromCellsMap();
        setAddrWeights(cellsFromCells, "cell cells");

        if (mpm_.hasOldCellVolumes())
        {
            // Volume weighted

            const scalarField& V = mpm_.oldCellVolumes();

            if (V.size() != sizeBeforeMapping())
            {
                FatalErrorInFunction
                    << "cellVolumes size " << V.size()
                    << " != old number of cells " << sizeBeforeMapping()
                    << ". Are your cellVolumes already mapped?"
                    << " (new number of cells " << size() << ")"
                    << abort(FatalError);
            }

            for (const auto& map : cellsFromCells)
            {
                // Get index, addressing
                const label celli = map.index();
                const labelList& mo = map.masterObjects();
                if (mo.empty()) continue;  // safety

                // wght[celli] is already sized and uniform weighted
                auto& wght_cell = wght[celli];

                scalar sumV = 0;
                forAll(mo, ci)
                {
                    wght_cell[ci] = V[mo[ci]];
                    sumV += V[mo[ci]];
                }
                if (sumV > VSMALL)
                {
                    for (auto& w : wght_cell)
                    {
                        w /= sumV;
                    }
                }
                else
                {
                    // Exception: zero volume. Use uniform mapping
                    wght_cell = (1.0/mo.size());
                }
            }
        }


        // Do mapped cells.
        // - may already have been set, so check if addressing still empty().

        {
            const labelList& map = mpm_.cellMap();

            // The cellMap.size() == nCells() anyhow
            for (label celli = 0; celli < mapperLen_; ++celli)
            {
                const label mappedi = map[celli];

                if (mappedi >= 0 && addr[celli].empty())
                {
                    // Mapped from a single cell
                    addr[celli].resize(1, mappedi);
                    wght[celli].resize(1, 1.0);
                }
            }
        }


        // Grab inserted points (for them the size of addressing is still zero)

        insertedObjectsPtr_ = std::make_unique<labelList>();
        auto& inserted = *insertedObjectsPtr_;

        // The nInsertedObjects_ already counted in the constructor
        if (nInsertedObjects_)
        {
            inserted.resize(nInsertedObjects_);

            label nInserted = 0;
            forAll(addr, i)
            {
                if (addr[i].empty())
                {
                    // Mapped from dummy cell 0
                    addr[i].resize(1, 0);
                    wght[i].resize(1, 1.0);

                    inserted[nInserted] = i;
                    ++nInserted;

                    // TBD: check (nInsertedObjects_ < nInserted)?
                    #ifdef FULLDEBUG
                    if (nInsertedObjects_ < nInserted)
                    {
                        FatalErrorInFunction
                            << "Unexpected insert of more than "
                            << nInsertedObjects_ << " items\n"
                            << abort(FatalError);
                    }
                    #endif
                }
            }
            // TBD: check (nInserted < nInsertedObjects_)?
            #ifdef FULLDEBUG
            if (nInserted < nInsertedObjects_)
            {
                WarningInFunction
                    << "Found " << nInserted << " instead of "
                    << nInsertedObjects_ << " items to insert\n";
            }
            #endif
            // The resize should be unnecessary
            inserted.resize(nInserted);
        }
    }
}


// void Foam::cellMapper::clearOut()
// {
//     directAddrPtr_.reset(nullptr);
//     interpAddrPtr_.reset(nullptr);
//     weightsPtr_.reset(nullptr);
//     insertedObjectsPtr_.reset(nullptr);
// }


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::cellMapper::cellMapper(const mapPolyMesh& mpm)
:
    mpm_(mpm),
    mapperLen_(mpm.mesh().nCells()),
    nInsertedObjects_(0),
    direct_
    (
        // Mapping without interpolation?
        mpm.cellsFromPointsMap().empty()
     && mpm.cellsFromEdgesMap().empty()
     && mpm.cellsFromFacesMap().empty()
     && mpm.cellsFromCellsMap().empty()
    )
{
    const auto& directMap = mpm_.cellMap();

    if (!mapperLen_)
    {
        // Empty mesh
        direct_ = true;
        nInsertedObjects_ = 0;
    }
    else if (direct_)
    {
        // Number of inserted cells (-ve values)
        nInsertedObjects_ = std::count_if
        (
            directMap.cbegin(),
            directMap.cbegin(mapperLen_),
            [](label i) { return (i < 0); }
        );
    }
    else
    {
        // Check if there are inserted cells with no owner
        // (check all lists)

        bitSet unmapped(mapperLen_, true);

        unmapped.unset(directMap);  // direct mapped

        for (const auto& map : mpm_.cellsFromPointsMap())
        {
            if (!map.empty()) unmapped.unset(map.index());
        }

        for (const auto& map : mpm_.cellsFromEdgesMap())
        {
            if (!map.empty()) unmapped.unset(map.index());
        }

        for (const auto& map : mpm_.cellsFromFacesMap())
        {
            if (!map.empty()) unmapped.unset(map.index());
        }

        for (const auto& map : mpm_.cellsFromCellsMap())
        {
            if (!map.empty()) unmapped.unset(map.index());
        }

        nInsertedObjects_ = label(unmapped.count());
    }
}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

Foam::cellMapper::~cellMapper()
{}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

Foam::label Foam::cellMapper::size() const
{
    // OR:  return mapperLen_;
    return mpm_.cellMap().size();
}


Foam::label Foam::cellMapper::sizeBeforeMapping() const
{
    return mpm_.nOldCells();
}


const Foam::labelUList& Foam::cellMapper::directAddressing() const
{
    if (!direct())
    {
        FatalErrorInFunction
            << "Requested direct addressing for an interpolative mapper."
            << abort(FatalError);
    }

    if (!insertedObjects())
    {
        // No inserted cells.  Re-use cellMap
        return mpm_.cellMap();
    }
    else
    {
        if (!directAddrPtr_)
        {
            calcAddressing();
        }

        return *directAddrPtr_;
    }
}


const Foam::labelListList& Foam::cellMapper::addressing() const
{
    if (direct())
    {
        FatalErrorInFunction
            << "Requested interpolative addressing for a direct mapper."
            << abort(FatalError);
    }

    if (!interpAddrPtr_)
    {
        calcAddressing();
    }

    return *interpAddrPtr_;
}


const Foam::scalarListList& Foam::cellMapper::weights() const
{
    if (direct())
    {
        FatalErrorInFunction
            << "Requested interpolative weights for a direct mapper."
            << abort(FatalError);
    }

    if (!weightsPtr_)
    {
        calcAddressing();
    }

    return *weightsPtr_;
}


const Foam::labelList& Foam::cellMapper::insertedObjectLabels() const
{
    if (!insertedObjectsPtr_)
    {
        if (!nInsertedObjects_)
        {
            // No inserted objects will be created
            return labelList::null();
        }

        calcAddressing();
    }

    return *insertedObjectsPtr_;
}


// ************************************************************************* //