#! /bin/bash


# Switches modem out of storage mode
sudo usb_modeswitch -v 0x12d1 -p 0x14fe -V 0x12d1 -P 0x1506 -M '55534243123456780000000000000011062000000100000000000000000000' &> /dev/null
sleep 30s

for path in $(ls /dev/ttyUSB*); do
        (
		MODEM=$path
		MODEMCMD=AT+CSQ
		INTERVAL=5

		# Writes a command to modem
		wrmodem () {
    			echo -ne "$*"'\r\n' >"$MODEM"
		}

		# Formats and prints the signal to be a percentage
		formatsig () {
        		result=$@

        		if [[ $result == *",99"* ]]
        			then
                		result=${result#$"+CSQ: "}
                		result=${result%$",99"}
                		result=$((result * 100))
                		result=$((result / 31))

                		echo "$result%"
				kill $$
        		fi
		}

		# Listens for responses from the modem
		{
    			trap EXIT
    			while true ; do
        			if read ; then
            				formatsig "$(tr -d \\r <<<"$REPLY")"
        			fi
    			done
		} <"$MODEM" &

		LOGGERPID=$!
		trap 'kill $LOGGERPID' EXIT

		# requester
		wrmodem "$MODEMCMD"
		sleep $INTERVAL
	)
done