class RuboCop::Cop::Style::Encoding

def comments
  processed_source.lines.each.with_index.with_object({}) do |(line, line_number), comments|
    next if line.start_with?(SHEBANG)
    comment = MagicComment.parse(line)
    return comments unless comment.valid?
    comments[line_number + 1] = comment
  end
end

def offense?(comment)
  comment.encoding_specified? && comment.encoding.casecmp('utf-8').zero?
end

def on_new_investigation
  return if processed_source.buffer.source.empty?
  comments.each do |line_number, comment|
    next unless offense?(comment)
    register_offense(line_number, comment)
  end
end

def register_offense(line_number, comment)
  range = processed_source.buffer.line_range(line_number)
  add_offense(range) do |corrector|
    text = comment.without(:encoding)
    if text.blank?
      corrector.remove(range_with_surrounding_space(range, side: :right))
    else
      corrector.replace(range, text)
    end
  end
end