class RuboCop::Cop::Style::Tab

def autocorrect(range)
  lambda do |corrector|
    corrector.replace(range, range.source.gsub(/\t/, '  '))
  end
end

def investigate(processed_source)
  str_lines = string_literal_lines(processed_source.ast)
  processed_source.lines.each_with_index do |line, index|
    match = line.match(/^( *)[\t ]*\t/)
    next unless match
    next if str_lines.include?(index + 1)
    spaces = match.captures[0]
    range = source_range(processed_source.buffer,
                         index + 1,
                         (spaces.length)...(match.end(0)))
    add_offense(range, range, MSG)
  end
end

def string_literal_lines(ast)
  # which lines start inside a string literal?
  return [] if ast.nil?
  ast.each_node(:str, :dstr).each_with_object(Set.new) do |str, lines|
    loc = str.location
    str_lines = if loc.is_a?(Parser::Source::Map::Heredoc)
                  body = loc.heredoc_body
                  (body.first_line)..(body.last_line)
                else
                  (loc.first_line + 1)..(loc.last_line)
                end
    lines.merge(str_lines.to_a)
  end
end