#!/bin/sh

set -e

testdir=$(dirname "$(readlink -f "$0")")
. "$testdir/.env"

lower=$1
shift
[ $# -gt 0 ] || set sh

# Detect if we're running inside the infamy container or on the host
# Inside the container, we can directly access the interfaces
# On the host, we need to use docker/podman exec
if ip link show "$lower" >/dev/null 2>&1; then
    # We can see the lower interface directly, so we're in the right namespace
    lookup_ifname() {
        ip -j link show | jq -r ".[] | select(.ifindex == $1) | .ifname"
    }
else
    # We're on the host, need to query the infamy container
    infamy=$(infamy 2>/dev/null) || {
        echo "ERROR: Cannot see interface '$lower' and no infamy container found" >&2
        echo "       Run this script from inside the infamy container or from the host with docker/podman available" >&2
        exit 1
    }
    lookup_ifname() {
        $(runner) exec $infamy ip -j link show | jq -r ".[] | select(.ifindex == $1) | .ifname"
    }
fi

for pid in $(pgrep -fx "sleep infinity"); do
    ifidxs=$(nsenter -t $pid -U -n ip -j link show | \
    		 jq '.[] | select(has("link_netnsid")) | .link_index')
    for ifidx in $ifidxs; do
	ifname=$(lookup_ifname $ifidx)
	if [ "$ifname" = "$lower" ]; then
	    exec nsenter -t $pid -U -n env PS1="(netns:$ifname) # " "$@"
	fi
    done
done

echo Found no namespace with interface stacked on $lower >&2
exit 1