/*---------------------------------------------------------------------------*\
   IH-Cantabria 2015 (http://www.ihcantabria.com/en/)
   IHFOAM 2015 (http://ihfoam.ihcantabria.com/) 

   Author(s):  Javier Lopez Lara (jav.lopez@unican.es)
               Gabriel Barajas   (barajasg@unican.es)
\*---------------------------------------------------------------------------*/

    //- Return Pi
    scalar PI()
    {
        #if OFVERSION >= 200
            const scalar PI = constant::mathematical::pi;
        #else
            const scalar PI = mathematicalConstant::pi;
        #endif
        return PI;
    }

    //- Return alphaName
    word alphaName()
    {
        #if OFVERSION >= 230
            const word an = "alpha.water";
        #else
            const word an = "alpha1";
        #endif
        return an;
    }

    //- Return prevalent direction - X or Y to sort groups of columns
    scalarField patchDirection ( vector span, scalar* dMin, scalar* dSpan )
    {
        const pointField& points = patch().patch().localPoints();
        if (span[0] >= span[1]) 
        {
            *dMin = gMin(points.component(0));
            *dSpan = gMax(points.component(0)) - *dMin;
            return patch().Cf().component(0); 
        }
        else
        {
            *dMin = gMin(points.component(1));
            *dSpan = gMax(points.component(1)) - *dMin;
            return patch().Cf().component(1);
        }
    }

    //- Return Zmax and Zmin of the patch faces
    void faceBoundsZ(scalarField* zSup, scalarField* zInf)
    {
        const label nF = patch().faceCells().size();
        scalarField zMax = Foam::scalarField(nF, -9999.0);
        scalarField zMin = Foam::scalarField(nF, 9999.0);
            
        const faceList& faces = this->patch().patch().localFaces();
        const List<vector>& points = this->patch().patch().localPoints();

        forAll( faces, faceI )
        {
            const face& f = faces[faceI];
            forAll(f, point)
            {
                scalar auxiliar = points[f[point]].component(2);

                zMax[faceI] = max(zMax[faceI], auxiliar);
                zMin[faceI] = min(zMin[faceI], auxiliar);
            }
        }

        *zSup = zMax;
        *zInf = zMin;
    }

    //- Calculate water levels on each paddle (same zSpan)
    scalarList calcWL 
        ( 
	    scalarField alphaCell, 
	    labelList cellGroup, 
	    scalar zSpan 
	)
    {
        scalarList groupTotalArea (nPaddles_,0.0); 
        scalarList groupWaterArea (nPaddles_,0.0); 
        scalarList heights (nPaddles_,0.0);

        const scalarField faceSurface = patch().magSf();

        forAll( patch().faceCells(), index ) 
        {
            groupTotalArea[cellGroup[index]-1] 
	        += faceSurface[index];
            groupWaterArea[cellGroup[index]-1] 
	        += faceSurface[index]*alphaCell[index];
        } 

        for (label i=0; i<=gMax(cellGroup)-1; i++)
        {
            reduce(groupTotalArea[i], sumOp<scalar>());
            reduce(groupWaterArea[i], sumOp<scalar>());
            heights[i] = groupWaterArea[i]/groupTotalArea[i]*zSpan;
        }

        return heights;
    }

    //- Calculate mean velocities on each paddle
    void calcUV 
        ( 
	    scalarField alphaCell, 
	    labelList cellGroup, 
	    scalarField UxCell, 
            scalarList* Ux, 
	    scalarField UyCell, 
	    scalarList* Uy 
	)
    {
       scalarList groupWaterArea (nPaddles_,0.0);
       scalarList groupUx (nPaddles_,0.0);
       scalarList groupUy (nPaddles_,0.0);

       const scalarField faceSurface = patch().magSf();

       forAll( patch().faceCells(), index ) 
       {
           groupWaterArea[cellGroup[index]-1] += 
               faceSurface[index]*alphaCell[index];

           groupUx[cellGroup[index]-1] += 
               UxCell[index]*alphaCell[index]*faceSurface[index];
           groupUy[cellGroup[index]-1] += 
               UyCell[index]*alphaCell[index]*faceSurface[index];
       } 

       for (label i=0; i<=nPaddles_-1; i++)
       {
           reduce(groupWaterArea[i], sumOp<scalar>());
            reduce(groupUx[i], sumOp<scalar>());
            reduce(groupUy[i], sumOp<scalar>());

            groupUx[i] = groupUx[i]/groupWaterArea[i];
            groupUy[i] = groupUy[i]/groupWaterArea[i];
        }

        *Ux = groupUx;
        *Uy = groupUy;
    }

    //- Mean of a scalarList
    scalar meanSL ( scalarList lst )
    {
        scalar aux = 0.0;
            
        forAll(lst,i)
        {
            aux += lst[i];
        }
            
        return aux/scalar(lst.size());
    }

    //- Reduce number of paddles if too high (paddles without cells)
    label decreaseNPaddles 
        ( 
	    label np, 
	    scalarField patchD, 
	    scalar dMin, 
	    scalar dSpan 
	)
    {
        scalarList dBreakPoints(np+1, 0.0); 

        while(1)
        {
            scalarList usedGroup (np,0.0); 

            for (label i=0; i<=np; i++)
            {
                dBreakPoints[i] = dMin + dSpan/(np)*i; 
            }

            forAll(patch().faceCells(), patchCells) 
            {
                for (label j=0; j<=np; j++) 
                {
                    if ( (patchD[patchCells]>=dBreakPoints[j]) && 
                        (patchD[patchCells]<dBreakPoints[j+1]) )
                    {
                        usedGroup[j] = 1.0;
                        continue;
                    }
                }      
            }

            reduce(usedGroup, maxOp<scalarList>());

            if ( gMin(usedGroup) < 0.5 )
            {
                Info
                    << "Reduced nPaddles from " << np
                    << " to " << np-1 << endl;
                np -= 1;
            }
            else
            {
                break;
            }
        }
        return np;
    }

    //- Own convenient definition of atan
    scalar arcTan ( scalar x, scalar y )
    {
        scalar A = 0.0;

        if( x > 0.0 )
        {
            A = atan(y/x);
        }
        else if ( y >= 0.0 && x < 0.0 )
        {
            A = PI() + atan(y/x);
        }
        else if ( y < 0.0 && x < 0.0 )
        {
            A = -PI() + atan(y/x);
        }
        else if ( y > 0.0 && x == 0.0 )
        {
            A = PI()/2.0;
        }        
        else if ( y < 0.0 && x == 0.0 )
        {
            A = -PI()/2.0;
        }
        else if ( y == 0.0 && x == 0.0 )
        {
            A = 0;
        }

        return A;
    }

    //- Calculate mean horizontal angle for each paddle
    scalarList meanPatchDirs ( labelList cellGroup )
    {
        const vectorField nVecCell = patch().nf();

        scalarList numAngles (nPaddles_, 0.0);
        scalarList meanAngle (nPaddles_, 0.0);

        forAll(patch().faceCells(), patchCells) 
        {
            meanAngle[cellGroup[patchCells]-1]
                += arcTan( nVecCell[patchCells].component(0), 
                nVecCell[patchCells].component(1));
            numAngles[cellGroup[patchCells]-1] += 1.0;
        }

        for (label i=0; i<=nPaddles_-1; i++)
        {
            reduce(meanAngle[i], sumOp<scalar>());
            reduce(numAngles[i], sumOp<scalar>());
            meanAngle[i] = meanAngle[i]/numAngles[i] + PI();
        }
        return meanAngle;
    }

    //- Calculate z-bounds for each paddle
    scalarList zSpanList 
        ( 
	    labelList cellGroup, 
	    scalarField zInf, 
	    scalarField zSup 
	)
    {
        scalarList zMaxL (nPaddles_, -9999.0);
        scalarList zMinL (nPaddles_,  9999.0);

        forAll(patch().faceCells(), patchCells) 
        {
            zMaxL[cellGroup[patchCells]-1] = 
	        max(zMaxL[cellGroup[patchCells]-1], zSup[patchCells] );
            zMinL[cellGroup[patchCells]-1] = 
                min(zMinL[cellGroup[patchCells]-1], zInf[patchCells] );
        }

        for (label i=0; i<=nPaddles_-1; i++)
        {
            reduce(zMaxL[i], maxOp<scalar>());
            reduce(zMinL[i], minOp<scalar>());
        }
        return zMaxL-zMinL;
    }

    //- In-line print for scalarLists
    label inlinePrint ( std::string name, scalarList SL )
    {
        Info << name << " " << SL.size() << "( ";
        forAll(SL, i)
        {
            Info << SL[i] << " ";
        }
        Info << ")\n" << endl;
        return 0;
    }

    //- Simple linear interpolation
    scalar interpolation 
        (
	    scalar x1, 
	    scalar x2, 
            scalar y1, 
            scalar y2, 
            scalar xInt 
        )
    {
        scalar yInt = y1 + (y2-y1)/(x2-x1)*(xInt-x1);
        return yInt;
    }

    //- Limit angle between -pi/2 and pi/2
    scalar limAngle (scalar ang)
    {
        ang = abs(ang);

        while (ang >= 2.0*PI())
        {
            ang -= 2.0*PI();
        }

        if ( ang >= PI()/2.0 && ang <= 3.0*PI()/2.0 )
        {
            return PI()/2.0;
        }
        else
        {
            return ang;
        }
    }

    //- Interpolation BO style
    scalar interpolatte 
        ( 
            scalar x1, 
            scalar x2, 
            scalar y1, 
            scalar y2, 
            scalar xInt 
        )
    {
        scalar yInt = (y1 + y2)*0.5;
        return yInt;
    }