#!/bin/sh

. /lib/functions.sh

LOG="logger -t $(basename "$0")[$$] -p"
INTERFACE=""
DEVICE=""

IFDOWN_EVENT=0

clean_up() {
	$LOG notice "Stopping mwan3track for interface \"${INTERFACE}\""
	exit 0
}

if_down() {
	$LOG info "Detect ifdown event on interface ${INTERFACE} (${DEVICE})"
	IFDOWN_EVENT=1
}

validate_track_method() {
	case "$1" in
		ping)
			# Assume that ping is installed
			;;
		arping)
			which arping 1>/dev/null 2>&1 || {
				$LOG warn "Missing arping. Please install iputils-arping package."
				return 1
			}
			;;
		httping)
			which httping 1>/dev/null 2>&1 || {
				$LOG warn "Missing httping. Please install httping package."
				return 1
			}
			;;
		*)
			$LOG warn "Unsupported tracking method: $track_method"
			return 2
			;;
	esac
}

main() {
	local reliability count timeout interval failure_interval
	local recovery_interval down up size
	local keep_failure_interval

	[ -z "$5" ] && echo "Error: should not be started manually" && exit 0

	INTERFACE=$1
	DEVICE=$2
	STATUS=$3
	SRC_IP=$4
	mkdir -p /var/run/mwan3track/$1
	trap clean_up SIGINT SIGTERM
	trap if_down SIGUSR1

	config_load mwan3
	config_get track_method $1 track_method ping
	validate_track_method $track_method || {
		$LOG warn "Using ping to track interface $INTERFACE avaliability"
		track_method=ping
	}
	config_get reliability $1 reliability 1
	config_get count $1 count 1
	config_get timeout $1 timeout 4
	config_get interval $1 interval 10
	config_get down $1 down 5
	config_get up $1 up 5
	config_get size $1 size 56
	config_get failure_interval $1 failure_interval $interval
	config_get_bool keep_failure_interval $1 keep_failure_interval 0
	config_get recovery_interval $1 recovery_interval $interval

	local score=$(($down+$up))
	local track_ips=$(echo $* | cut -d ' ' -f 5-99)
	local host_up_count=0
	local lost=0
	local sleep_time=0
	local turn=0

	if [ "$STATUS" = "unknown" ]; then
		echo "unknown" > /var/run/mwan3track/$1/STATUS
		score=0
	else
		echo "online" > /var/run/mwan3track/$1/STATUS
	fi
	while true; do

		sleep_time=$interval

		for track_ip in $track_ips; do
			if [ $host_up_count -lt $reliability ]; then
				case "$track_method" in
					ping)
						ping -I $DEVICE -c $count -W $timeout -s $size -q $track_ip &> /dev/null ;;
					arping)
						arping -I $DEVICE -c $count -w $timeout -q $track_ip &> /dev/null ;;
					httping)
						httping -y $SRC_IP -c $count -t $timeout -q $track_ip &> /dev/null ;;
				esac
				if [ $? -eq 0 ]; then
					let host_up_count++
					echo "up" > /var/run/mwan3track/$1/TRACK_${track_ip}
				else
					let lost++
					echo "down" > /var/run/mwan3track/$1/TRACK_${track_ip}
				fi
			else
				echo "skipped" > /var/run/mwan3track/$1/TRACK_${track_ip}
			fi
		done

		if [ $host_up_count -lt $reliability ]; then
			let score--

			if [ $score -lt $up ]; then
				score=0
				[ ${keep_failure_interval} -eq 1 ] && {
					sleep_time=$failure_interval
				}
			else
				sleep_time=$failure_interval
			fi

			if [ $score -eq $up ]; then
				echo "offline" > /var/run/mwan3track/$1/STATUS
				$LOG notice "Interface $1 ($2) is offline"
				env -i ACTION=ifdown INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				score=0
			fi
		else
			if [ $score -lt $(($down+$up)) ] && [ $lost -gt 0 ]; then
				$LOG info "Lost $(($lost*$count)) ping(s) on interface $1 ($2)"
			fi

			let score++
			lost=0

			if [ $score -gt $up ]; then
				echo "online" > /var/run/mwan3track/$1/STATUS
				score=$(($down+$up))
			elif [ $score -le $up ]; then
				sleep_time=$recovery_interval
			fi

			if [ $score -eq $up ]; then
				$LOG notice "Interface $1 ($2) is online"
				echo "online" > /var/run/mwan3track/$1/STATUS
				env -i ACTION=ifup INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				exit 0
			fi
		fi

		let turn++
		mkdir -p "/var/run/mwan3track/${1}"
		echo "${lost}" > /var/run/mwan3track/$1/LOST
		echo "${score}" > /var/run/mwan3track/$1/SCORE
		echo "${turn}" > /var/run/mwan3track/$1/TURN
		echo "$(date +'%s')" > /var/run/mwan3track/$1/TIME

		host_up_count=0
		sleep "${sleep_time}" &
		wait

		if [ "${IFDOWN_EVENT}" -eq 1 ]; then
			score=0
			echo "offline" > /var/run/mwan3track/$1/STATUS
			IFDOWN_EVENT=0
		fi
	done
}

main "$@"
