#!/usr/bin/env bash

working_dir="$(dirname $(realpath $0))"

# -------------
# - Some Variables
# -------------

LOCK_DIR="/tmp/$(basename $0).LOCK"

KILL_SIGNAL=HUP

CHECK_COMMANDS="$*"


# -------------
# - Some functions
# -------------

usage() {

   
   [[ -n  "$1" ]] && error "$1"

   
   [[ $terminal ]] && echo -e "
\033[1mUsage:\033[m

   $(basename $0) COMMAND [COMMAND] ..

\033[1mDescription\033[m

   Searches for zombie (defunct) child prozesses from given command(s). If such
   processes exists, the script tries to kill them by sending a HUP signal to
   the parent process.

   At least one command as a cammand line option must be gicen.

\033[1mExample:\033[m
	
   Search for (and delete) defunct child prozesses of parent '/usr/local/php/bin/php-cgi'

      $(basename $0) /usr/local/php/bin/php-cgi

   Search for (and delete) defunct child prozesses of parent processes
   '/usr/local/sympa/bin/sympa_msg.pl' and '/usr/local/sympa/bin/bulk.pl'
   
      $(basename $0) /usr/local/sympa/bin/sympa_msg.pl /usr/local/sympa/bin/bulk.pl

"

   clean_up 1

}

clean_up() {

   # Perform program exit housekeeping
   rm -rf "$LOCK_DIR"
   exit $1
}

trim() {
    local var="$*"
    var="${var#"${var%%[![:space:]]*}"}"   # remove leading whitespace characters
    var="${var%"${var##*[![:space:]]}"}"   # remove trailing whitespace characters
    echo -n "$var"
}

fatal(){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[31m\033[1mFatal\033[m ]: $*"
      echo ""
      echo -e "   \033[31m\033[1mScript was interupted\033[m!"
   else
      echo "[ Fatal ]: $*"
      echo ""
      echo "              Script was terminated...."
   fi
   echo ""
   clean_up 1
}

error (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[31m\033[1mError\033[m ]: $*"
   else
      echo "[ Error ]: $*"
   fi
   echo ""
}

warn (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarning\033[m ]: $*"
   else
      echo "[ Warning ]: $*"
   fi
   echo ""
}

info (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[32m\033[1mInfo\033[m ]: $*"
   else
      echo "[ Info ]: $*"
   fi
   echo ""
}
info_terminal (){
   if $terminal ; then
      echo ""
      echo -e "   [ \033[32m\033[1mInfo\033[m ]: $*"
      echo ""
   fi
}

ok (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[32m\033[1mOk\033[m ]: $*"
   else
      echo "[ Ok ]: $*"
   fi
   echo ""
}


# -------------
# - Check some prerequisites
# -------------

# - Is this script running on terminal ?
# -
if [[ -t 1 ]] ; then
   terminal=true
else
   terminal=false
fi


# - Print help?
# -
if [[ "$(trim $*)" = "-h" ]] || [[ "$(trim $*)" = "--help" ]] ; then
	 usage
fi

if [[ -z "$(which basename)" ]]; then
   fatal 'It seems "basename" is not installed, but needed!'
fi

if [[ -z "$(which realpath)" ]]; then
   fatal 'It seems "realpath" is not installed, but needed!'
fi


if [[ -z "$CHECK_COMMANDS" ]]; then
	usage "At least one command must be given."
else
   for _COMMAND in ${CHECK_COMMANDS[@]} ; do
      if [[ ! -x "$_COMMAND" ]]; then
	      fatal "no binary/script '$_COMMAND' found on the server"
      fi
   done
fi


# -------------
# - Jobhandling 
# -------------

# - If job already runs, stop execution..
# -
if mkdir "$LOCK_DIR" 2> /dev/null ; then

   ## - Remove lockdir when the script finishes, or when it receives a signal
   trap clean_up SIGHUP SIGINT SIGTERM

else

   datum="$(date +"%d.%m.%Y %H:%M")"

	fatal "A previos instance of that script \"$(basename $0)\" seems already be running."

   exit 1

fi


# -------------
#  Checking ..
# -------------

if $terminal ; then
   echo ""
   echo -e "   \033[1mCheck for zombie (defunct) child prozesses\033[m"
   echo "   =========================================="
fi

for _COMMAND in ${CHECK_COMMANDS[@]} ; do

if $(ps -Ao"stat,command" | grep "$(basename ${_COMMAND})" | grep -v grep | grep -e '^[zZ]' > /dev/null 2>&1)
then

   warn "Found Zombie Processes '${_COMMAND}' on '$(hostname -f)':"

   ps -Ao"stat,user,pid,ppid,command" | grep "$(basename ${_COMMAND})" | grep -v grep | grep -e '^[zZ]'

   membefore=$(cat /proc/meminfo | grep Committed_AS | awk '{print $2}')

   info "Trying a graceful kill to the concerning parents with signal '$KILL_SIGNAL' .."

	# - Sending the kill signal
	# -
   ps -Ao"stat,pid,ppid,command" | grep "$(basename ${_COMMAND})" | grep -v grep | grep -e '^[zZ]' \
      | awk '{ print $3 }' | sort -u | xargs --no-run-if-empty kill -$KILL_SIGNAL

   if [[ "$?" -eq 0 ]];then
      sleep 10
      ok "Cleaning up zombie processes '${_COMMAND}' seems succsessfully finisched"

      memafter=`cat /proc/meminfo | grep Committed_AS | awk '{print $2}'`

      info "`expr $membefore - $memafter` KB RAM has been freed"
   else
      error "Cleaning up zombie processes '${_COMMAND}' failed!"
   fi
else
   info_terminal "No zombie prossses '${_COMMAND}' found."
fi
done

if $terminal ; then
   echo ""
fi
clean_up 0