class Reline::ANSI

def self.cursor_pos
  begin
    res = +''
    m = nil
    @@input.raw do |stdin|
      @@output << "\e[6n"
      @@output.flush
      loop do
        c = stdin.getc
        next if c.nil?
        res << c
        m = res.match(/\e\[(?<row>\d+);(?<column>\d+)R/)
        break if m
      end
      (m.pre_match + m.post_match).chars.reverse_each do |ch|
        stdin.ungetc ch
      end
    end
    column = m[:column].to_i - 1
    row = m[:row].to_i - 1
  rescue Errno::ENOTTY
    begin
      buf = @@output.pread(@@output.pos, 0)
      row = buf.count("\n")
      column = buf.rindex("\n") ? (buf.size - buf.rindex("\n")) - 1 : 0
    rescue Errno::ESPIPE
      # Just returns column 1 for ambiguous width because this I/O is not
      # tty and can't seek.
      row = 0
      column = 1
    end
  end
  Reline::CursorPos.new(column, row)
end