#!/usr/bin/env bash

check_string_ps=""
if [[ -x /usr/lib/postfix/sbin/master ]]; then
   check_string_ps="/usr/lib/postfix/sbin/master"
elif [[ -x "/usr/lib/postfix/master" ]] ; then
   check_string_ps="/usr/lib/postfix/master"
elif [[ -x "/usr/libexec/postfix/master" ]] ; then
   check_string_ps="/usr/libexec/postfix/master"
fi

postfix_init_script=""
if [[ -x "/etc/init.d/postfix" ]] ; then
   postfix_init_script="/etc/init.d/postfix"
fi

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 ""
}

detect_os () {

   if $(which lsb_release > /dev/null 2>&1) ; then

      os_dist="$(lsb_release -i | awk '{print tolower($3)}')"
      os_version="$(lsb_release -r | awk '{print tolower($2)}')"
      os_codename="$(lsb_release -c | awk '{print tolower($2)}')"

      if [[ "$os_dist" = "debian" ]]; then
         if $(echo "$os_version" | grep -q '\.') ; then
            os_version=$(echo "$os_version" | cut --delimiter='.' -f1)
         fi
      fi

   elif [[ -e "/etc/os-release" ]]; then

      . /etc/os-release

      os_dist=$ID
      os_version=${VERSION_ID}

   fi

   # remove whitespace from os_dist and os_version
   os_dist="${os_dist// /}"
   os_version="${os_version// /}"

}

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

if [[ -z $check_string_ps ]]; then
   fatal "$(basename $0): Postfix 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 $postfix_init_script ]]; then
      fatal "$(basename $0): Missing Postfix Init-Script!"
   fi
fi

# - Detect linux distribution
# -
detect_os


#---------------------------------------
#-----------------------------
# Check if Postfix Mailservice is running
#-----------------------------
#---------------------------------------

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


   if $systemd_supported ; 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

      # - Don't Start/Stop Services if package management is running (apt,aptitude,dpkg)
      # -
      if ( [[ "${os_dist,,}" = "debian" ]] || [[ "${os_dist,,}" = "ubuntu" ]] ) \
            && $(lsof /var/lib/dpkg/lock >/dev/null 2>&1) ; then
         warn "It seems that package management (apt,dpkg) is running. Exiting restarting the service .."
      else
         $systemctl stop postfix > /dev/null 2> ${LOCK_DIR}/err_msg.log
         if [[ $? -ne 0 ]]; then
            error "$(cat ${LOCK_DIR}/err_msg.log)"
         fi

         sleep 10

         # - Don't Start/Stop Services if package management is running (apt,aptitude,dpkg)
         # -
         if ( [[ "${os_dist,,}" = "debian" ]] || [[ "${os_dist,,}" = "ubuntu" ]] ) \
               && $(lsof /var/lib/dpkg/lock >/dev/null 2>&1) ; then
               warn "It seems that package management (apt,dpkg) is running. Omit starting the service .."
         else
            $systemctl start postfix > /dev/null 2> ${LOCK_DIR}/err_msg.log
            if [[ $? -ne 0 ]]; then
               error "$(cat ${LOCK_DIR}/err_msg.log)"
            fi
         fi
      fi

   else

      # - Don't Start/Stop Services if package management is running (apt,aptitude,dpkg)
      # -
      if ( [[ "${os_dist,,}" = "debian" ]] || [[ "${os_dist,,}" = "ubuntu" ]] ) \
            && $(lsof /var/lib/dpkg/lock >/dev/null 2>&1) ; then
         warn "It seems that package management (apt,dpkg) is running - Exiting restarting the service .."
      else
         $postfix_init_script stop > /dev/null 2>&1
         if [[ $? -ne 0 ]]; then
            error "Stopping Postfix Mailservice failed!"
         fi

         sleep 10

         # - Don't Start/Stop Services if package management is running (apt,aptitude,dpkg)
         # -
         if ( [[ "${os_dist,,}" = "debian" ]] || [[ "${os_dist,,}" = "ubuntu" ]] ) \
               && $(lsof /var/lib/dpkg/lock >/dev/null 2>&1) ; then
            warn "It seems that package management (apt,dpkg) is running. Omit starting the service .."
         else
            $postfix_init_script start > /dev/null 2>&1
            if [[ $? -ne 0 ]]; then
               error "Starting Postfix Mailservice failed!"
            fi
         fi

      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 Postfix Mailservice failed!"
   else
      ok "Postfix Mailservice is up and running."
   fi
         
else
   if $LOGGING ; then
      ok "Postfix Mailservice is up and running."
   fi
fi

rm -rf $LOCK_DIR
exit 0