class RuboCop::Cop::Performance::FlatMap

def on_send(node)
  left, second_method, flatten_param = *node
  return unless FLATTEN.include?(second_method)
  flatten_level, = *flatten_param
  expression, = *left
  _array, first_method = *expression
  return unless first_method == :map || first_method == :collect
  message = MSG
  if cop_config['EnabledForFlattenWithoutParams'] && flatten_level.nil?
    message = MSG + FLATTEN_MULTIPLE_LEVELS
  else
    return unless flatten_level == 1
  end
  range = Parser::Source::Range.new(node.loc.expression.source_buffer,
                                    expression.loc.selector.begin_pos,
                                    node.loc.selector.end_pos)
  add_offense(node, range, format(message, first_method, second_method))
end