static H3Error vertexRotations()

in h3_vertex.c [53:107]
42 lines of code
13 McCabe index (conditional complexity)

static H3Error vertexRotations(H3Index cell, int *out) {
    // Get the face and other info for the origin
    FaceIJK fijk;
    H3Error err = _h3ToFaceIjk(cell, &fijk);
    if (err) {
        return err;
    }
    int baseCell = H3_EXPORT(getBaseCellNumber)(cell);
    int cellLeadingDigit = _h3LeadingNonZeroDigit(cell);

    // get the base cell face
    FaceIJK baseFijk;
    _baseCellToFaceIjk(baseCell, &baseFijk);

    int ccwRot60 = _baseCellToCCWrot60(baseCell, fijk.face);

    if (_isBaseCellPentagon(baseCell)) {
        // Find the appropriate direction-to-face mapping
        PentagonDirectionFaces dirFaces;
        // We never hit the end condition
        int p = 0;
        for (; p < NUM_PENTAGONS; p++) {
            if (pentagonDirectionFaces[p].baseCell == baseCell) {
                dirFaces = pentagonDirectionFaces[p];
                break;
            }
        }
        if (p == NUM_PENTAGONS) {
            return E_FAILED;
        }

        // additional CCW rotation for polar neighbors or IK neighbors
        if (fijk.face != baseFijk.face &&
            (_isBaseCellPolarPentagon(baseCell) ||
             fijk.face ==
                 dirFaces.faces[IK_AXES_DIGIT - DIRECTION_INDEX_OFFSET])) {
            ccwRot60 = (ccwRot60 + 1) % 6;
        }

        // Check whether the cell crosses a deleted pentagon subsequence
        if (cellLeadingDigit == JK_AXES_DIGIT &&
            fijk.face ==
                dirFaces.faces[IK_AXES_DIGIT - DIRECTION_INDEX_OFFSET]) {
            // Crosses from JK to IK: Rotate CW
            ccwRot60 = (ccwRot60 + 5) % 6;
        } else if (cellLeadingDigit == IK_AXES_DIGIT &&
                   fijk.face ==
                       dirFaces.faces[JK_AXES_DIGIT - DIRECTION_INDEX_OFFSET]) {
            // Crosses from IK to JK: Rotate CCW
            ccwRot60 = (ccwRot60 + 1) % 6;
        }
    }
    *out = ccwRot60;
    return E_SUCCESS;
}