#!/usr/bin/env sh
# Configurable Variables
[ -z $DOCKER_SOCK_PATH ] && DOCKER_SOCK_PATH="/tmp/docker.sock"
[ -z $NETWORK_NAME ] && NETWORK_NAME="proxy"
[ -z $RESOLVE_DOCKERHOST ] && RESOLVE_DOCKERHOST=false
[ -z $HOST_CONF_PATH ] && HOST_CONF_PATH="/tmp/hosts"
[ -z $DOCKER_HOSTNAME_VAR ] && DOCKER_HOSTNAME_VAR="VIRTUAL_HOST"

query_docker () {
    curl --unix-socket $DOCKER_SOCK_PATH --silent -g http://v1.41/$1$2
}

get_host_list() {
    PROXY_HOST_CONF=""
    CONTAINER_LIST=$(query_docker "containers/json" "?filters={%22network%22:[%22${NETWORK_NAME}%22],%22status%22:[%22running%22]}" | jq -cr '.[].Id')

    for id in $CONTAINER_LIST
    do
        # Query individual container to access relevant data
        CONTAINER_DATA=$(query_docker "containers/${id}/json")
        if $RESOLVE_DOCKERHOST
        then
            HOST_IP=$(echo $CONTAINER_DATA | jq -cr '.NetworkSettings.Networks.proxy.IPAddress')
        else
            HOST_IP="127.0.0.1"
        fi
        # Filter Env for HOSTNAME, remove list parenthesis and split/only keep values
        HOST_NAMES=$(echo $CONTAINER_DATA | jq -cr ".Config.Env[] | select(contains(\"$DOCKER_HOSTNAME_VAR=\")) | split(\"=\")[1]")

        for hostname in $HOST_NAMES
        do
            PROXY_HOST_CONF="$PROXY_HOST_CONF\n$HOST_IP $hostname # Added by hostman"
        done
    done
    echo $PROXY_HOST_CONF
}

update_host_list() {
    FILTERED_HOSTS=$(grep -ve "# Added by hostman$" $HOST_CONF_PATH)
    echo -e "$FILTERED_HOSTS$(get_host_list)" > $HOST_CONF_PATH
}

update_host_list
# cannot filter because reailine no longer recognized lines otherwise (check how IFS changes)
query_docker "events" | while  true
do
    read -r;
    # wait for related events to finish
    while [ $? -eq 0 ]
    do
        read -t 5 -r;
    done
    update_host_list
done