public Set<Category> possibleCategories() {
Set<Category> set = new HashSet<>();
if (currentCategory != null) {
set.add(Category.parse(currentCategory));
}
if (categories != null) {
for (CategoryField field : categories) {
Set<Category> cats =
Category.advance(Category.parse(field.category), field.season, currentSeason());
if (set.isEmpty()) set.addAll(cats);
else set.retainAll(cats);
}
}
set.remove(new Category(Category.CategoryBase.UNDEFINED));
return set;
}
