#!/usr/bin/env bash

# monitor-ip.sh checks whether the external IP address has changed, and if so, sends a mail notification and Gotify.

host=$(hostname)

redbold="\033[1;31m"
greenbold="\033[1;32m"
green="\033[0;32m"
yellow="\033[0;33m"
yellowbold="\033[1;33m"
bold="\033[1m"
#bold_under="\033[1;4m"
underline="\033[4m"
reset="\033[0m"

notif=true

### Help Function:
Help() {
  echo "monitor-ip.sh checks whether the external IP address has changed,"
  echo " and if so, sends a mail notification and Gotify."
  echo
  echo "Syntax:     monitor-ip.sh [OPTION]" 
  echo "Example:    monitor-ip.sh -h display this help !"
  echo
  echo "Options:"
  echo "-h     Print this Help."
  echo "-n     Just check IP. Don't send notification'."
}

while getopts "hn" options; do
  case "${options}" in
  	n) notif=false ;;
    h|*) Help ; exit 2 ;;
  esac
done
shift "$((OPTIND-1))"

MSMTP=$(which msmtp)
SSMTP=$(which ssmtp)

if [ -n $MSMPT ] ; then  
	MAIL=$MSMTP
elif [ -n $SSMTP ] && [ -z $MAIL ] ; then
	MAIL=$SSMTP
else
	echo "No msmtp or ssmtp binary found in PATH: $PATH" ; exit 1
fi


dotenv () {
  set -a
  # shellcheck disable=SC1091
  [ -f ".env" ] && . ".env" ||  echo -e "${red}\nNo .env file found ! No token for gotify.${reset}"
  set +a
}

send_mail_notification() {
	FromHost=$(hostname)

	# User variables:
	SendMailFrom="router@clicclac.info"
	SendMailTo="router@clicclac.info"
	SubjectTag="monitor_ip.sh"

	printf "\nSending email notification  ...\n"

$MAIL $SendMailTo << __EOF
From: "$FromHost" <$SendMailFrom>
date:$(date -R)
To: <$SendMailTo>
Subject: [$SubjectTag] L IP sur $FromHost a changée !
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

Ancienne IP: $old_ip_externe
Nouvelle IP: $ip_externe

__EOF
}

send_gotify_notification() {
	now=$(date +"%d-%m-%Y %T")
	gotify_server="https://gotify.maboiteverte.fr"
	TITLE="IP has changed on $host"
	MESSAGE="**L'IP externe a changé:**\n\n - ancienne IP: $old_ip_externe\n - **nouvelle IP:  $ip_externe**\n\n [^]: $now\n"
	PRIORITY=8
	URL="$gotify_server/message?token=$token_gotify&?format=markdown"
	
	echo -e "Sending notification to $gotify_server ..."
	
	curl -L -S -s --data '{"message": "'"${MESSAGE}"'", "title": "'"${TITLE}"'", "priority":'"${PRIORITY}"', "extras": {"client::display": {"contentType": "text/markdown"}}}' -H 'Content-Type: application/json' "$URL"  > /dev/null

	[ $? -eq 0 ] && echo -e "${greenbold}Gotify notification sent successfully !${reset}" || echo -e "${redbold}error sending Gotify notification !${reset}"
}

dotenv

old_ip_externe=$(cat monitor-ip.pref)

ip_externe=$(dig @resolver4.opendns.com myip.opendns.com +short)
echo $ip_externe > monitor-ip.pref

if [ "$ip_externe" != "$old_ip_externe" ]; then
    echo "L'IP externe a changé"
    echo "IP externe: $ip_externe"
    
    if [ $notif == true ]; then
		send_mail_notification

		#send_gotify_notification
		pushover -a "syno" -m "L'IP externe a changé:<br />  - ancienne IP: $old_ip_externe<br />  - nouvelle IP: $ip_externe" -f 1
	fi
	
else
    echo "L'IP externe n'a pas changé"
    echo "IP externe: $ip_externe"
    
fi