#!/bin/sh

# This is a very simple job server which can be used to run commands in
# a different context.  For example, for things that need to run from
# inside an OSX session rather than in the ssh-ed context.

here="$(cd $(dirname "$0"); pwd)"
pidfile="$here/pid"

unset LD_LIBRARY_PATH

###############################################################################
server() {
  case "$serverstatus" in
  ( running ) echo "Server already running" 1>&2; exit 1 ;;
  ( stopped ) ;;
  ( dead    ) echo "Cleaning up after dead server" 1>&2; rm -f "$pidfile" ;;
  ( *       ) echo "Unknown server status" 1>&2; exit 1 ;;
  esac
  echo "Server started, pid=$$"
  echo "$$" > "$pidfile"
  trap cleanup 0 3 9 15
  while true; do
    cd "$here"
    jobs="$(find * -name "*.job")"
    if [[ "$jobs" = "" ]]; then sleep 2; continue; fi
    echo "$jobs" | \
    while read job; do
      n="${job%.job}"
      echo "Running job #$n..."
      cd "$HOME"
      . "$here/$job" > "$here/$n.out" 2>&1
      echo "$?" > "$here/$n.ret"
      cd "$here"
      echo "Done"
      rm -f "$here/$job"
    done
  done
}

cleanup() { rm -f "$pidfile"; }

###############################################################################
client() {
  case "$serverstatus" in
  ( running ) ;;
  ( stopped ) echo "No server running" 1>&2; exit 1 ;;
  ( dead    ) echo "Server died" 1>&2; exit 1 ;;
  ( *       ) echo "Unknown server status" 1>&2; exit 1 ;;
  esac
  c="0"
  if [[ -e "$here/counter" ]]; then c="$(cat "$here/counter")"; fi
  c=$(( (c+1) % 10000 ))
  echo "$c" > "$here/counter"
  c="$here/$c"
  echo "cd \"$(pwd)\"" > "$c.tmp"
  if [[ "x$1" = "x-" ]]; then cat; else echo "$@"; fi >> "$c.tmp"
  mv "$c.tmp" "$c.job"
  while [[ -e "$c.job" ]]; do sleep 1; done
  cat "$c.out"; rm -f "$c.out"
  stat="$(cat "$c.ret")"; rm -f "$c.ret"
  exit "$stat"
}

###############################################################################
status() {
  echo "$serverstatus"
}

if [[ ! -e "$pidfile" ]]; then serverstatus="stopped"
else
  pid="$(cat "$pidfile")"
  if ps -p "$pid" | grep -q "$pid"; then serverstatus="running"
  else serverstatus="dead"; fi
fi

###############################################################################

case "x$1" in
( "x--help"   ) echo "--start:  start server"
                echo "--status: find the status of the running server, if any"
                echo "Anything else, run it on the server; use \`-' to read"
                echo "  shell code from stdin"
                exit ;;
( "x--start"  ) shift; server "$@" ;;
( "x--status" ) shift; status "$@" ;;
( *           )        client "$@" ;;
esac