#!/bin/bash

#######################################################################################################################
#
# 	Sample code for a SMS relay server with gammu
#   Script reads SMS received by gammu daemon and forwards them to another phone number or sends it to an eMail or does some other stuff with the SMS
#
#	This script is referred by https://www.linux-tips-and-tricks.de/en/raspberry/559-use-zte-ml190-usb-pen-drive-to-create-a-sms-relay-server
#	which explains in detail how to create and manage the SMS relay server
#
#######################################################################################################################
#
#    Copyright (c) 2020 framp at linux-tips-and-tricks dot de
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#######################################################################################################################

GAMMU_INPUT_DIR="/var/spool/gammu/inbox"
SOURCE_PHONE="+4947114712"
TARGET_PHONE="+4947134714"
MYSELF=${0##*/}
MYNAME=${MYSELF%.*}
EMAIL_TARGET="user@dummy.com"
EMAIL_ADMIN="admin@dummy.com"
SERVER_NAME="SMSRelay"
LOG="/var/log/$MYNAME.log"
NOTIFY_TARGET=1
NOTIFY_ADMIN=2
NOTIFY_BOTH=$(( $NOTIFY_TARGET | $NOTIFY_ADMIN ))

function send() { # rcv subject message
	#echo "$3" | gammu-smsd-inject TEXT $TARGET_PHONE
	if (( $1 & $NOTIFY_TARGET )); then
		echo "--- relay sms to target $EMAIL_TARGET"	
	   echo "$3" | mail -s "$SERVER_NAME: $2" $EMAIL_TARGET 
	fi

	if (( $1 & $NOTIFY_ADMIN )); then
		echo "--- relay sms to admin $EMAIL_ADMIN"	
	   echo "$3" | mail -s "$SERVER_NAME: $2" $EMAIL_ADMIN
	fi
}

function handleSMS() { # number msg

	local number="$1"
	local msg="$2"

	case "$msg" in
		*\*echo*)
			echoMessage="$(cut -f 2- -d ' ' <<< "$msg")"
		   echo "--- echo"	
			send $NOTIFY_ADMIN "*echo command received" "$echoMessage"
			;;	
		*\*status*)
		   echo "--- status"	
			send $NOTIFY_ADMIN "*status command received"
			;;
		*\*help*)
		   echo "--- help"	
			send $NOTIFY_ADMIN "*help command received" "*echo MESSAGE, *status, *restart, *cancel"
			;;
		*\*restart*)
		   echo "--- restart"	
		 	send $NOTIFY_ADMIN "*restart command received" "SMS relay server will be restarted soon" 
			sleep 1m
			systemctl restart gammu-smsd
			;;
		*\*cancel*)
		   echo "--- cancel"	
		 	send $NOTIFY_ADMIN "*cancel command received" "SMS relay server will be stopped soon" 
			sleep 1m
			systemctl stop gammu-smsd
			exit 0
			;;
	 	*) 
		   echo "--- default"	
	  		send $NOTIFY_BOTH "SMS received from $number" "$msg" 
			;;
	esac
 }

for i in $SMS_MESSAGES; do
	echo "Processing $i: $1"
   number="SMS_${i}_NUMBER"	
	echo "SMS_NUMBER: ${!number}"
   text="SMS_${i}_TEXT"	
	echo "SMS_TEXT: ${!text}"
	echo "$(date +"%Y%m%d-%H%M%S") SMS '$1' received"
	handleSMS "${!number}" "${!text}" 
done