#!/usr/bin/env ruby

require 'json'

require 'optparse'

options = {}

OptionParser.new do |opts|

  opts.banner = "Usage: #{$0} [OPTIONS]"

  opts.on('-k', '--key [NAME]', 'Key in json to look for a timestamp.') do |value|
    options[:key] = value
  end

end.parse!

required_options = [:key]
required_options.each do |option|
  unless options[option]
    $stderr.puts "Can not run #{option.to_s} was not given."
    exit 1
  end
end

times = []
distances = []
previous = nil

STDIN.each_line do |line|
  object = JSON.parse(line)
  times << object[options[:key]]
end

times.sort do |a, b|
  a <=> b
end.each do |time|
  if previous
    distances << time - previous
  end
  previous = time
end

distances.each do |distance|
  puts "distance #{distance}"
end