# redefine ip command to use FRR when it is available

# default route distance
IF_METRIC=${IF_METRIC:-210}

# get status of FRR
function frr_alive () {
    /usr/lib/frr/watchfrr.sh all_status
    if [ "$?" -eq "0" ] ; then
        logmsg info "FRR status: running"
        return 0
    else
        logmsg info "FRR status: not running"
        return 1
    fi
}

# convert ip route command to vtysh
function iptovtysh () {
    # prepare variables for vtysh command
    local VTYSH_ACTION=$3
    local VTYSH_NETADDR=""
    local VTYSH_GATEWAY=""
    local VTYSH_DEV=""
    local VTYSH_TAG="210"
    local VTYSH_DISTANCE=$IF_METRIC
    # convert default route to 0.0.0.0/0
    if [ "$4" == "default" ] ; then
        VTYSH_NETADDR="0.0.0.0/0"
    else
        VTYSH_NETADDR=$4
    fi
    # add /32 to ip addresses without netmasks
    if [[ ! $VTYSH_NETADDR =~ ^.*/[[:digit:]]+$ ]] ; then
        VTYSH_NETADDR="$VTYSH_NETADDR/32"
    fi
    shift 4
    # get gateway address
    if [ "$1" == "via" ] ; then
        VTYSH_GATEWAY=$2
        shift 2
    fi
    # get device name
    if [ "$1" == "dev" ]; then
        VTYSH_DEV=$2
        shift 2
    fi
    # get distance
    if [ "$1" == "metric" ]; then
        VTYSH_DISTANCE=$2
        shift 2
    fi

    # Add route to VRF routing table
    local VTYSH_VRF_NAME=$(/usr/sbin/ip link show dev $VTYSH_DEV | sed -nre '1s/.* master ([^ ]*) .*/\1/p')
    if /usr/sbin/ip -d link show dev $VTYSH_DEV | grep -q "vrf_slave"; then
        VTYSH_VRF="vrf $VTYSH_VRF_NAME"
    fi
    VTYSH_CMD="ip route $VTYSH_NETADDR $VTYSH_GATEWAY $VTYSH_DEV tag $VTYSH_TAG $VTYSH_DISTANCE $VTYSH_VRF"

    # delete route if the command is "del"
    if [ "$VTYSH_ACTION" == "del" ] ; then
        VTYSH_CMD="no $VTYSH_CMD"
    fi
    logmsg info "Converted vtysh command: \"$VTYSH_CMD\""
}

# delete the same route from kernel before adding new one
function delroute () {
    logmsg info "Checking if the route presented in kernel: $@"
    if /usr/sbin/ip route show $@ | grep -qx "$1 " ; then
        logmsg info "Deleting IP route: \"/usr/sbin/ip route del $@\""
        /usr/sbin/ip route del $@
    fi
}

# replace ip command with this wrapper
function ip () {
    # pass comand to system `ip` if this is not related to routes change
    if [ "$2" != "route" ] ; then
        logmsg info "Passing command to /usr/sbin/ip: \"$@\""
        /usr/sbin/ip $@
    else
        # if we want to work with routes, try to use FRR first
        if frr_alive ; then
            delroute ${@:4}
            iptovtysh $@
            logmsg info "Sending command to vtysh"
            vtysh -c "conf t" -c "$VTYSH_CMD"
        else
            # add ip route to kernel
            logmsg info "Modifying routes in kernel: \"/usr/sbin/ip $@\""
            /usr/sbin/ip $@
        fi
    fi
}