class SlstrProductFactory extends AbstractProductFactory {

    static String getGridIndex(String bandName) {
        String[] nameParts = bandName.split("_");
        int lastPartIndex = nameParts.length - 1;
        int index = lastPartIndex;
        int firstIndexOfPartWithTwoLetters = -1;
        while (index >= 0) {
            if (ArrayUtils.isMemberOf(nameParts[index], SLSTR_GRID_INDEXES)) {
                return nameParts[index];
            } else if (firstIndexOfPartWithTwoLetters < 0 && nameParts[index].length() == 2) {
                firstIndexOfPartWithTwoLetters = index;
            }
            index--;
        }
        if (firstIndexOfPartWithTwoLetters >= 0) {
            return nameParts[firstIndexOfPartWithTwoLetters];
        }
        if (nameParts[lastPartIndex].length() > 1) {
            return nameParts[lastPartIndex].substring(nameParts[lastPartIndex].length() - 2);
        }
        return nameParts[lastPartIndex];
    }

      SlstrProductFactory(Sentinel3ProductReader productReader);

}