class JsonbAccessor::FieldsMap

def extract_typed_and_nested_fields(typed_and_nested_fields)
  typed_and_nested_fields.each_with_object(nested: {}, typed: {}) do |(attribute_name, type_or_nested), grouped_attributes|
    group = type_or_nested.is_a?(Hash) ? grouped_attributes[:nested] : grouped_attributes[:typed]
    group[attribute_name] = type_or_nested
  end
end

def implicitly_typed_fields(value_fields)
  value_fields.each_with_object({}) do |field_name, implicitly_typed_fields|
    implicitly_typed_fields[field_name] = :value
  end
end

def initialize(value_fields, typed_and_nested_fields)
  grouped_fields = extract_typed_and_nested_fields(typed_and_nested_fields)
  nested_fields, typed_fields = grouped_fields.values_at(:nested, :typed)
  self.typed_fields = implicitly_typed_fields(value_fields).merge(typed_fields)
  self.nested_fields = nested_fields
end

def names
  typed_fields.keys + nested_fields.keys
end