#!/bin/sh

VERBOSE=no

PIDS=`pidof -x "$0"`

# make sure pidof sees us
if [ -z "$PIDS" ]; then
	exec "$0"
	exit 1
fi

GSM_DEVICE="/dev/ttySAC0"
GSM_POWER="/sys/devices/platform/neo1973-pm-gsm.0/power_on"
GSM_RESET="/sys/devices/platform/neo1973-pm-gsm.0/reset"

GSM_COMMANDS="Z E0V1 +CFUN=1 +COPS=0"

gsm_running () {
	if [ "$PIDS" != "$$" ]; then
		return 0
	else
		return 1
	fi
}

gsm_send () {
	cmd="$1"
	echo -ne "AT${cmd}\r" > "$GSM_DEVICE"
}

# this function might block forever
gsm_wait () {
	ret="UNKNOWN"

	while read status; do
		case "$status" in
			OK*)
				ret="OK"
				;;
			ERROR*)
				ret="ERROR"
				;;
			*)
				ret="UNKNOWN"
				;;
		esac
		if [ "x$ret" != "xUNKNOWN" ]; then
			break
		fi
	done < "$GSM_DEVICE"

	if [ "x$ret" != "xOK" ]; then
		return 1
	fi

	return 0
}

gsm_setup () {
	[ $VERBOSE == "yes" ] && echo -n "Powering up GSM modem..."
	echo 0 > "$GSM_POWER"; sleep 1
	echo 1 > "$GSM_POWER"; sleep 1
	echo 1 > "$GSM_RESET"; sleep 1
	echo 0 > "$GSM_RESET"; sleep 4
	[ $VERBOSE == "yes" ] && echo "done"

	stty -F "$GSM_DEVICE" cooked -opost -echo crtscts 115200
}

gsm_wakeup () {
	[ $VERBOSE == "yes" ] && echo "Waking up GSM modem"

	# there is at most one OK/ERROR even if we send multiple commands
	gsm_send ""
	gsm_send ""
	gsm_send ""

	if gsm_wait; then
		[ $VERBOSE == "yes" ] && echo "GSM modem awake"
		return 0
	else
		echo "failed to wake up GSM modem"
		return 1
	fi
}

start () {
	gsm_setup

	if gsm_wakeup; then
		for cmd in $GSM_COMMANDS
		do
			[ $VERBOSE == "yes" ] && echo "Sending AT$cmd"
			gsm_send "$cmd"

			if ! gsm_wait; then
				echo "AT$cmd failed"
				break
			fi
		done
	fi
}

set -e

case "$1" in
	start)
		if gsm_running; then
			echo "Another instance is already running"
			exit 1
		fi

		start &
		;;
	stop)
		if gsm_running; then
			PIDS=`pidof -x -o "$$" "$0"`
			echo -n "Stopping other instances..."
			kill $PIDS
			echo "done"
		fi
		;;
	*)
		echo "Usage: $0 {start|stop}"
		exit 1
		;;
esac