#!/bin/sh

docker_api() {
    local url="$1"
    shift
    ## Note: the 'localhost' part is ignored by curl, but it is not
    ## we can't remove it (like: http:/$url). If it does work on ubuntu's
    ## curl, it doesn't work on alpine's curl.
    curl -s --unix-socket /var/run/docker.sock "http://localhost/$url" "$@"
}

exname=$(basename "$0")
usage="$exname [-h|--help] SERVICE SIGNAL"

service=
signal=
while [ "$1" ]; do
    case "$1" in
        "--help"|"-h")
            echo "$usage" >&2
            exit 0
        ;;
        *)
            [ -z "$service" ] && { service=$1 ; shift ; continue ; }
            [ -z "$signal" ] && { signal=$1 ; shift ; continue ; }
            echo "Unexpected argument '$1'." >&2
            exit 1
        ;;
    esac
    shift
done

if [ -z "$service" ]; then
    echo "You must provide a service name as first argument." >&2
    echo "$usage" >&2
    exit 1
fi

if [ -z "$signal" ]; then
    echo "You must provide a signal to send to $service aargument." >&2
    echo "$usage" >&2
    exit 1
fi


if ! containers=$(
        docker_api containers/json \
                   -G --data-urlencode filters="{\"label\": [\"compose.service=$service\"]}"); then
   echo "Curl toward socket for list of containers failed." >&2
   exit 1
fi
if ! container_id=$(echo "$containers" | jq -r '.[0].Id'); then
    echo "Failed to query following JSON:" >&2
    echo "$containers" >&2
    exit 1
fi

if [ "$container_id" -a "$container_id" != "null" ]; then
    echo "Sending $signal to $service" >&2
    docker_api "containers/${container_id}/kill" --data "signal=$signal"
else
    echo "No container found for service '$service'." >&2
fi

true