#! /bin/sh -e

silently () {
  ## Run the command discarding all of its output.
  "$@" >/dev/null 2>&1
}

restart_services () {
  ## Restart the services we know about.

  echo -n "Restarting services:"

  ## Make sure that the server is actually running.
  if ! silently tripectl version; then
    echo " tripe server not running."
    return 0
  fi

  ## Find out which of our services are actually configured to start.
  ## We'll assume that a link to the service script is a good indication.
  need_restart=$(perl -e '
	  for my $svc (@ARGV) { $svc{$svc} = 1; }
	  for my $link (</etc/tripe/services/*>) {
	    next unless -l $link;
	    my $targ = readlink $link;
	    next unless defined $targ;
	    next unless $targ =~
	      m#/usr/lib/(?:[^/]+/)?tripe/services/([^/]+)#;
	    next unless exists $svc{$1};
	    print "$link\n";
	  }' "$@")

  ## If there's nothing to do then don't bother with the rest.
  any=nil
  for svc in $need_restart; do any=t; break; done
  case $any in nil) echo " none configured."; return 0 ;; esac

  ## Restart the services.  This is more than a little tricky.
  for svc in $need_restart; do

    ## Find out about the service.
    set -- $("$svc" --version)
    name="$1" version="$2"

    ## Write some progress.
    echo -n " $name"

    ## If there's an instance of the service running already then we ask it
    ## to quit.  This is where everything gets complicated.
    if silently tripectl svcensure "$name"; then

      ## So, what we want to do is ask the service to quit, and make sure it
      ## actually has done before starting the new version.  Conveniently,
      ## the server emits a notification when a service quits.  Now all we
      ## have to do is wait a reasonable time for the notification.
      ##
      ## So we read the output of tripectl(1).  Of course, to do this, we
      ## must keep its standard input open, so we'll sleep for a bit.  We can
      ## use this to implement our timeout.  The only problem is curtailing
      ## the wait early if (as we expect) the service actually quits on time.
      ## The answer is /very/ cheesy: we'll report the process-id of our
      ## sleep(1) process through the server's notification mechanism.  Then,
      ## when we see the `SVCRELEASE', we kill the sleep(1) and return
      ## success.
      if ! { echo "watch n"
	     echo svcsubmit "$name" quit
	     sleep 1& sleepkid=$!
	     echo notify tripe-peer-services.postinst.$$ SLEEPKID=$sleepkid
	     wait $sleepkid || :
	   } |
	   tripectl |
	   { while read line; do
	       case "$line" in
		 "NOTE USER tripe-peer-services.postinst.$$ SLEEPKID="*)
		   sleepkid=${line##*=}
		   ;;
		 "NOTE SVCRELEASE $name")
		   kill $sleepkid
		   exit 0
		   ;;
	       esac
	     done; exit 1; }
      then
	echo -n " (STUCK)"
	continue
      fi
    fi

    ## Restart the service.  Pass `--startup' because (a) the server might
    ## have started recently, and failed to start our services, and (b) our
    ## services are (modulo some annoying warning messages) idempotent
    ## anyway.
    if ! "$svc" --daemon --startup; then echo -n " (FAILED)"; fi
  done
  echo "."
}

restart_services conntrack connect watch

#DEBHELPER#