# Script to modify linux-stable recipe to build latest kernel tag
# Requires ruby. To install ruby: sudo apt-get install ruby1.9.1

def get_latest_tag(force_tag)
  return force_tag if (force_tag && force_tag != '')
  x=`git ls-remote --tags git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git master v\*`
  x.scan(/refs\/tags\/(v[\d\.]+)\n/).flatten.last
end

def need_to_run(tag)
  if !File.exists? "latest-linux-stable-run"
    update_latest_run(tag)
    return true
  else
    last_run = File.open("latest-linux-stable-run").read
    update_latest_run(tag)
    tag.strip != last_run.strip
  end
end

def update_latest_run(tag)
  f = File.new("latest-linux-stable-run", 'w')
  f.write(tag)
  f.close
end

def update_recipe(recipe,tag)
  `cat #{recipe} | sed 's/SRCREV = ".*"/SRCREV = "#{tag}"/g' > #{recipe}.tmp; mv #{recipe}.tmp #{recipe}`
end

########################################
########## START SCRIPT BODY ###########
########################################
recipe = ARGV[0]
force_tag = ARGV[1]

tag = get_latest_tag(force_tag)

if need_to_run(tag)
  update_recipe(recipe,tag)
  puts "Done. #{recipe} udpated to use tag #{tag}\n"
  exit 0
else
  puts "There are no new tags. We are done! \n"
  exit 1
end