H3Error _h3ToFaceIjk()

in h3_h3Index.c [1004:1053]
31 lines of code
12 McCabe index (conditional complexity)

H3Error _h3ToFaceIjk(H3Index h, FaceIJK *fijk) {
    int baseCell = H3_GET_BASE_CELL(h);
    if (NEVER(baseCell < 0) || baseCell >= NUM_BASE_CELLS) {
        // Base cells less than zero can not be represented in an index
        // To prevent reading uninitialized memory, we zero the output.
        fijk->face = 0;
        fijk->coord.i = fijk->coord.j = fijk->coord.k = 0;
        return E_CELL_INVALID;
    }
    // adjust for the pentagonal missing sequence; all of sub-sequence 5 needs
    // to be adjusted (and some of sub-sequence 4 below)
    if (_isBaseCellPentagon(baseCell) && _h3LeadingNonZeroDigit(h) == 5)
        h = _h3Rotate60cw(h);

    // start with the "home" face and ijk+ coordinates for the base cell of c
    *fijk = baseCellData[baseCell].homeFijk;
    if (!_h3ToFaceIjkWithInitializedFijk(h, fijk))
        return E_SUCCESS;  // no overage is possible; h lies on this face

    // if we're here we have the potential for an "overage"; i.e., it is
    // possible that c lies on an adjacent face

    CoordIJK origIJK = fijk->coord;

    // if we're in Class III, drop into the next finer Class II grid
    int res = H3_GET_RESOLUTION(h);
    if (isResolutionClassIII(res)) {
        // Class III
        _downAp7r(&fijk->coord);
        res++;
    }

    // adjust for overage if needed
    // a pentagon base cell with a leading 4 digit requires special handling
    int pentLeading4 =
        (_isBaseCellPentagon(baseCell) && _h3LeadingNonZeroDigit(h) == 4);
    if (_adjustOverageClassII(fijk, res, pentLeading4, 0) != NO_OVERAGE) {
        // if the base cell is a pentagon we have the potential for secondary
        // overages
        if (_isBaseCellPentagon(baseCell)) {
            while (_adjustOverageClassII(fijk, res, 0, 0) != NO_OVERAGE)
                continue;
        }

        if (res != H3_GET_RESOLUTION(h)) _upAp7r(&fijk->coord);
    } else if (res != H3_GET_RESOLUTION(h)) {
        fijk->coord = origIJK;
    }
    return E_SUCCESS;
}