#!/usr/bin/env ruby

def main
  output = `ls #{ARGV.map {|a| "\"#{a}\""}.join(' ')}`
  lines = output.split("\n")
  i = 0
  most_commas = 0
  number_of_commas = []
  unchanged_line_indexes = []
  new_lines = lines.map do |line|
    if line =~ /^[-dl][-rwxsS]{9}[@+\s]?/
      size = line.split[4]
      if size =~ /^\d+$/
        new_size = commaify(size)
        new_line = line.sub(size, new_size)
        n = new_size.count(',')
        number_of_commas << n
        most_commas = n if n > most_commas
      end
    end
    unless new_line
      unchanged_line_indexes << i
      number_of_commas << 0
      new_line = line
    end
    i += 1
    new_line
  end
  new_lines.each_with_index do |line, i|
    if line =~ /^[-dl][-rwxsS]{9}[@+\s]?/
      size = line.split[4]
      padded_size = (' ' * (most_commas - number_of_commas[i])) + size
      new_lines[i] = line.sub(size, padded_size)
    end
  end
  puts new_lines.join("\n")
end

def commaify(size)
  number_with_delimiter(size)
end

def number_with_delimiter(n, delimiter = ',')
  n.to_s.gsub(/(\d)(?=(\d\d\d)+(?!\d))/, "\\1#{delimiter}")
end

main if __FILE__ == $0