class Solargraph::Source::SourceChainer

def get_signature_data_at index
  brackets = 0
  squares = 0
  parens = 0
  index -=1
  in_whitespace = false
  while index >= 0
    pos = Position.from_offset(@source.code, index)
    break if index > 0 and @source.comment_at?(pos)
    break if brackets > 0 or parens > 0 or squares > 0
    char = @source.code[index, 1]
    break if char.nil? # @todo Is this the right way to handle this?

    if brackets.zero? and parens.zero? and squares.zero? and [' ', "\r", "\n", "\t"].include?(char)
      in_whitespace = true
    else
      if brackets.zero? and parens.zero? and squares.zero? and in_whitespace
        unless char == '.' or @source.code[index+1..-1].strip.start_with?('.')
          old = @source.code[index+1..-1]
          nxt = @source.code[index+1..-1].lstrip
          index += (@source.code[index+1..-1].length - @source.code[index+1..-1].lstrip.length)
          break
        end
      end
      if char == ')'
        parens -=1
      elsif char == ']'
        squares -=1
      elsif char == '}'
        brackets -= 1
      elsif char == '('
        parens += 1
      elsif char == '{'
        brackets += 1
      elsif char == '['
        squares += 1
      end
      if brackets.zero? and parens.zero? and squares.zero?
        break if ['"', "'", ',', ';', '%'].include?(char)
        break if ['!', '?'].include?(char) && index < offset - 1
        break if char == '$'
        if char == '@'
          index -= 1
          if @source.code[index, 1] == '@'
            index -= 1
          end
          break
        end
      elsif parens == 1 || brackets == 1 || squares == 1
        break
      end
      in_whitespace = false
    end
    index -= 1
  end
  index + 1
end