class RuboCop::Cop::Style::Encoding

def autocorrect(range)
  lambda do |corrector|
    corrector.remove(range_with_surrounding_space(range: range,
                                                  side: :right))
  end
end

def encoding_line_number(processed_source)
  line_number = 0
  line_number += 1 if processed_source[line_number].start_with?(SHEBANG)
  line_number
end

def encoding_omitable?(line)
  line =~ ENCODING_PATTERN
end

def investigate(processed_source)
  return if processed_source.buffer.source.empty?
  line_number = encoding_line_number(processed_source)
  return unless (@message = offense(processed_source, line_number))
  range = processed_source.buffer.line_range(line_number + 1)
  add_offense(range, location: range, message: @message)
end

def offense(processed_source, line_number)
  line = processed_source[line_number]
  MSG_UNNECESSARY if encoding_omitable?(line)
end