#!/usr/bin/ruby

require 'fileutils'

def main local, remote, to="/tmp/"
    to_file = get_remote(remote, to)
    rsize = File.size(to_file)
    lsize = File.size(local)
    if rsize > lsize
        FileUtils.cp(to_file, local)
    elsif rsize == lsize
        # do nothing.
    elsif rsize < lsize
        send_remote(local, remote)
    else
        raise "must not happen"
    end
end

def get_remote remote, to
    to_file = File.join(to, remote.gsub(%r{/}, '_'))
    system("scp #{remote} #{to_file}")
    to_file
end

def send_remote local, remote
    system("scp #{local} #{remote}")
end

local = ARGV.shift
remote = ARGV.shift

main(local, remote)