#!/bin/sh
#
# Node Exporter startup script for Slackware Linux
#

BASE=node_exporter
SERVER=/usr/bin/${BASE}

# Default options.
if [ -f /etc/default/node_exporter ]; then
  . /etc/default/node_exporter
fi

NODE_EXPORTER_USER=${NODE_EXPORTER_USER:=nobody}
NODE_EXPORTER_ARGS=${NODE_EXPORTER_ARGS:=""}
NODE_EXPORTER_LOG_FACILITY=${NODE_EXPORTER_LOG_FACILITY:=daemon.info}
NODE_EXPORTER_PID=/var/run/node_exporter/node_exporter.pid

# Check if server is present.
if [ ! -x ${SERVER} ]; then
  echo "${SERVER} not present or not executable"
  exit 1
fi

# Check if daemon is present.
if [ ! -x /usr/bin/daemon ]; then
  echo "/usr/bin/daemon not present or not executable"
  echo "> slackpkg install daemon"
  exit 1
fi

wait_for_pid () {
  try=0
 
  while test $try -lt 5 ; do
    case "$1" in
      'created')
      if [ -f "$2" ] ; then
        try=''
        break
      fi
      ;;
 
      'removed')
      if [ ! -f "$2" ] ; then
        try=''
        break
      fi
      ;;
    esac
 
    echo -n .
    try=`expr $try + 1`
    sleep 1
 
  done
}

node_exporter_start() {
  if [ -f $NODE_EXPORTER_PID ]; then
    echo "$NODE_EXPORTER_PID file exists, $BASE is probably running"
    exit 0
  else
    echo -n "Starting ${BASE} ..."
    daemon --user=$NODE_EXPORTER_USER \
	   --pidfile=$NODE_EXPORTER_PID \
	   --output=$NODE_EXPORTER_LOG_FACILITY -- \
	   $SERVER $NODE_EXPORTER_ARGS

    wait_for_pid created $NODE_EXPORTER_PID

    if [ -n "$try" ] ; then
      echo " failed"
      exit 1
    else
      echo " done"
    fi

  fi
}

node_exporter_stop() {
  echo -n "Stopping ${BASE} ..."
  if [ -f $NODE_EXPORTER_PID ]; then
    kill $(cat $NODE_EXPORTER_PID)

    wait_for_pid removed $NODE_EXPORTER_PID

    if [ -n "$try" ] ; then
      echo " failed"
      exit 1
    else
      echo " done"
    fi
  else
    echo "not running"
  fi 
}

node_exporter_restart() {
  node_exporter_stop
  node_exporter_start
}

node_exporter_status() {
  if [ -f $NODE_EXPORTER_PID ]; then
    echo "Status of ${BASE}: running"
  else
    echo "Status of ${BASE}: stopped"
  fi
}


case "$1" in
  'start')
    node_exporter_start
    ;;
  'stop')
    node_exporter_stop
    ;;
  'restart')
    node_exporter_restart
    ;;
  'status')
    node_exporter_status
    ;;
  *)
    echo "Usage: $0 {start|stop|restart|status}"
esac

exit 0