#!/usr/bin/env bash

sshd_binary="$(which sshd)"

check_string_ps="$sshd_binary"

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 ""
}

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

# - Is SSH Service installed ?
# -
if [[ -z "$sshd_binary" ]]; then
   fatal "$(basename $0): SSH Service seems NOT to be installed"
else
   check_string_ps="$sshd_binary"
fi


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

systemd_supported=false
if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
   systemd_supported=true
fi

SSHD_SERVICE_FILE=
SSHD_SYSV_INIT_SCRIPT=

if $systemd_supported ; then
   if systemctl -t service list-unit-files \
         | grep -e "^ssh" \
         | grep -q -E "(enabled|disabled)" 2> /devnull ; then

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

if [[ -z "$SSHD_SERVICE_FILE" ]]; then
   if [[ -x "/etc/init.d/ssh" ]]; then
      SSHD_SYSV_INIT_SCRIPT="/etc/init.d/ssh"
   elif [[ -x "/etc/init.d/sshd" ]]; then
      SSHD_SYSV_INIT_SCRIPT="/etc/init.d/sshd"
   fi
fi

if [[ -z "$SSHD_SERVICE_FILE" ]] && [[ -z "$SSHD_SYSV_INIT_SCRIPT" ]] ; then
   fatal 'Neither an init-script nor a service file for SSH found!'
fi


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

if $LOGGING ; then
   echo -e "\n   Check if SSH service is running.."
   echo -e "   ================================="
fi
if ! ps -e f | grep -E "[[:digit:]]\ .*\s?${check_string_ps}" | grep -v grep > /dev/null ; then
   error "SSH service seems to be down! Trying to restart service now.."

   if [[ -n "$SSHD_SERVICE_FILE" ]] ; then
      $systemctl daemon-reload > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
      sleep 2
      $systemctl stop $SSHD_SERVICE_FILE > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
      sleep 10
      $systemctl start $SSHD_SERVICE_FILE > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
   else
      $SSHD_SYSV_INIT_SCRIPT stop > /dev/null 2>&1
      if [[ $? -ne 0 ]]; then
         error "Stopping SSH service failed!"
      fi
      sleep 10
      $SSHD_SYSV_INIT_SCRIPT start > /dev/null 2>&1
      if [[ $? -ne 0 ]]; then
         error "Starting SSH service 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 SSH service failed!"
   else
      ok "SSH service is up and running."
   fi
         
else
   if $LOGGING ; then
      ok "SSH service is up and running."
   fi
fi

rm -rf $LOCK_DIR
exit 0