#!/usr/bin/env bash

LOCK_DIR="/tmp/$(basename $0).$$.LOCK"
log_file="${LOCK_DIR}/${script_name%%.*}.log"

#---------------------------------------
#-----------------------------
# Base Function(s)
#-----------------------------
#---------------------------------------

usage() {


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


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

   $(basename $0) <Systemd-Service>

\033[1mDescription\033[m

   Script checks if given service is running and tries to restart service
   if it is not running.

\033[1mOptions\033[m

   No Options available

\033[1mExample:\033[m
   
   Check if apache2 service is runnin. Restart service if needed.

      $(basename $0) apache2

"

   clean_up 1
}


clean_up() {

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


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

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

warn (){
   if $LOGGING || $terminal ; then
      echo ""
      if $terminal ; then
         echo -e "   [ \033[33m\033[1mWarn\033[m ]  $*"
      else
         echo "   [ Warn ]  $*"
      fi
      echo ""
   fi
}

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

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

blank_line() {
   if $terminal ; then
      echo ""
   fi
}

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


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

# - Run 'clean_up' for signals SIGHUP SIGINT SIGTERM
# -
trap clean_up SIGHUP SIGINT SIGTERM

# - Create lock directory '$LOCK_DIR"
#
mkdir "$LOCK_DIR"



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

# - Running in a terminal?
# -
if [[ -t 1 ]] ; then
   terminal=true
   LOGGING=true
else
   terminal=false
   LOGGING=false
fi

if [[ -n "$1" ]] ; then
   service_name=$1
else
	error "No Service given!"
	usage
fi


# - Systemd supported ?
# -
systemd=$(which systemd)
systemctl=$(which systemctl)

systemd_supported=false
if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
   systemd_supported=true
else
   fatal "Systemd is not present!"
fi

if systemctl -t service list-unit-files \
      | grep -e "^${service_name,,}d" \
      | grep -q -E "(enabled|disabled)" 2> /devnull ; then

   SYSTEMD_SERVICE="$(systemctl -t service list-unit-files | grep -e "^${service_name,,}d" | awk '{print$1}' | head -1)"
elif systemctl -t service list-unit-files \
      | grep -e "^${service_name,,}" \
      | grep -q -E "(enabled|disabled)" 2> /devnull ; then

   SYSTEMD_SERVICE="$(systemctl -t service list-unit-files | grep -e "^${service_name,,}" | awk '{print$1}' | head -1)"
fi

if [[ -z "$SYSTEMD_SERVICE" ]]; then
   fatal "Systemd Service '${service_name}' not found!"
fi


#---------------------------------------
#-----------------------------
# Check if service is running
#-----------------------------
#---------------------------------------

if $LOGGING ; then
	declare -i _length="${#service_name}"
   echo -e "\n   Check if $service_name service is running.."
   echo -en "   ==============================="
	declare -i i=0
	while [[ $i -lt $_length ]] ; do
		echo -n "="
		((i++))
	done
	echo ""
fi

need_restart=false
if $(systemctl is-active $SYSTEMD_SERVICE > /dev/null 2>&1) ; then
   eval $(systemctl show -p MainPID ${SYSTEMD_SERVICE})
   if [[ -n "$MainPID" ]] && [[ $MainPID -gt 0 ]]; then
      if $(ps ax | grep -q -E "^\s*${MainPID} " 2> /dev/null) ; then
         ok "$service_name service is up and running."
      else
         error "$service_name service seems to be down! Trying to restart service now.."
         need_restart=true
      fi
   else
      ok "$service_name service is up and running."
		warn "Cannot determine MainPID for Service '$service_name', but the status is 'active'."
   fi
   
else
   error "$service_name service seems to be down! Trying to restart service now.."
   need_restart=true
fi

if $need_restart ; then

   $systemctl daemon-reload > /dev/null 2> $log_file
   if [[ $? -ne 0 ]]; then
      error "$(cat $log_file)"
   fi
   sleep 2
   $systemctl stop $SYSTEMD_SERVICE > /dev/null 2> $log_file
   if [[ $? -ne 0 ]]; then
      error "$(cat $log_file)"
   fi
   sleep 10
   $systemctl start $SYSTEMD_SERVICE > /dev/null 2> $log_file
   if [[ $? -ne 0 ]]; then
      error "$(cat $log_file)"
   fi

   sleep 5
   if $(systemctl is-active $SYSTEMD_SERVICE > /dev/null 2>&1) ; then
      eval $(systemctl show -p MainPID ${SYSTEMD_SERVICE})
      if [[ -n "$MainPID" ]] && [[ $MainPID -gt 0 ]]; then
         if $(ps ax | grep -q -E "^\s*${MainPID} " 2> /dev/null) ; then
            ok "$service_name service is now up and running. New PID is '$MainPID'"
            if ! $terminal ; then
               echo "   [ Ok ]    service is now up and running. New PID is '$MainPID'"
            fi
         else
            error "Restarting $service_name service failed!"
         fi
      else
         warn "Cannot determine MainPID for Service '$service_name', but the status is 'active'."
         ok "$service_name service is up and running."
         if ! $terminal ; then
            echo "   [ Ok ]    service is now up and running. New PID is '$MainPID'"
            echo "   [ Warn ]  Cannot determine MainPID for Service '$service_name', but the status is 'active'."
         fi
      fi
   else
      error "Restarting $service_name service failed!"
   fi
      
fi

clean_up 0