#!/usr/bin/env bash

check_string_ps=""
if [[ -f "/usr/sbin/named" ]] ; then
	check_string_ps="/usr/sbin/named"
fi

alternate_addr="oopen.de google.com heise.de debian.org ubuntu.com"


# - used, if systemd is NOT supported
bind_init_script=""
if [[ -x "/etc/init.d/bind9" ]] ; then
   bind_init_script="/etc/init.d/bind9"
fi

# - Used if systemd is supported
# -
service_name=bind9

LOCK_DIR=`mktemp -d`


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

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
   echo ""
   rm -rf $LOCK_DIR
   exit 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[1mWarn\033[m ]  $*"
   else
      echo "   [ Warn ]  $*"
   fi
   echo ""
}

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

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

fatal(){
   echo ""
   echo -e "   [ Fatal ] $*"
   echo ""
   echo -e "\tScript terminated.."
   echo ""
   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"
}


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

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

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

if [[ -z $check_string_ps ]]; then
   fatal "$(basename $0): Bind Nameservice seems NOT to be installed"
fi

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

systemd_supported=false
if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
   systemd_supported=true
else
   if [[ ! -x $bind_init_script ]]; then
      fatal "$(basename $0): Missing Bind Init-Script!"
   fi
fi


#---------------------------------------
#-----------------------------
# Check if Bind Nameservice is running
#-----------------------------
#---------------------------------------

if $LOGGING ; then
   echo -e "\n   Check if Bind Nameservice is running.."
   echo -e "   ======================================"
fi

for ip_addr in $alternate_addr  ; do
   ping -c3 $ip_addr >> /dev/null 2>&1
   if [ $? -eq 0 ]; then

      PID=$(ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}"| grep -v grep | awk '{print$2}')
      if [[ "X${PID}" = "X" ]]; then
         break
      else
      
         if $LOGGING ; then
            ok "Bind Nameservice is up and running."
         fi
         exit 0
      fi
   fi
done;

error "Bind Nameservice seems to be down! Trying to restart service now.."

if $systemd_supported ; then
	$systemctl stop $service_name > /dev/null 2> ${LOCK_DIR}/err_msg.log
	if [[ $? -ne 0 ]]; then
		error "$(cat ${LOCK_DIR}/err_msg.log)"
	fi
	sleep 10
	$systemctl start $service_name > /dev/null 2> ${LOCK_DIR}/err_msg.log
	if [[ $? -ne 0 ]]; then
		error "$(cat ${LOCK_DIR}/err_msg.log)"
	fi
else
	$bind_init_script stop > /dev/null 2>&1
	if [[ $? -ne 0 ]]; then
		error "Stopping Bind Nameservice failed!"
	fi
	sleep 10
	$bind_init_script start > /dev/null 2>&1
	if [[ $? -ne 0 ]]; then
		error "Starting Bind Nameservice failed!"
	fi
fi

declare -i counter=0
PID=$(ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}"| grep -v grep | awk '{print$2}')
while [[ "X${PID}" = "X" ]]; do
	sleep 1
	PID=$(ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}"| grep -v grep | awk '{print$2}')
	if [[ $counter -gt 10 ]]; then
		break
	else
		((counter++))
	fi
done

if [[ "X${PID}" = "X" ]] ; then
	error "Restarting Bind Nameservice failed!"
else
	ok "Bind Nameservice is up and running."
fi
   
exit 0;