/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2015 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 "surfaceFields.H"
#include "syncTools.H"

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

template <class Type>
void Foam::pressurePIDControlInletVelocityFvPatchVectorField::faceZoneAverage
(
    const word& name,
    const GeometricField<Type, fvsPatchField, surfaceMesh>& field,
    scalar& area,
    Type& average
) const
{
    const fvMesh& mesh = patch().boundaryMesh().mesh();
    const auto& pbm = mesh.boundaryMesh();

    bitSet isMasterFace(syncTools::getInternalOrMasterFaces(mesh));

    const faceZone& zone = mesh.faceZones()[name];

    area = 0;
    average = Type(Zero);

    for (const label meshFacei : zone)
    {
        if (mesh.isInternalFace(meshFacei))
        {
            const scalar da = mesh.magSf()[meshFacei];

            area += da;
            average += da*field[meshFacei];
        }
        else if (isMasterFace[meshFacei])
        {
            const label patchi = pbm.patchID(meshFacei);
            const label patchFacei = pbm[patchi].whichFace(meshFacei);
            const scalar da = mesh.magSf().boundaryField()[patchi][patchFacei];

            area += da;
            average += da*field.boundaryField()[patchi][patchFacei];
        }
    }

    reduce(area, sumOp<scalar>());
    reduce(average, sumOp<Type>());

    average /= (area + VSMALL);
}


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