#!/usr/bin/env bash
###########################################################################
##  Copyright (C) Wizardry and Steamworks 2025 - License: MIT            ##
###########################################################################
#set -x

# check for Docker socket
[ ! -S /run/docker.sock ] && \
    echo "Docker socket file not found!" && \
    exit 1
[ -z "${POINTER_ADDRESS}" ] && \
    echo "The POINTER_ADDRESS environment variable has to be set to point to the traefik IP address." && \
    exit 1

# this must be set by the container
[ -z "${MDNS_DOMAIN}" ] && MDNS_DOMAIN='local'

# start dbus and wait for socket
dbus-uuidgen > /var/lib/dbus/machine-id
mkdir -p /run/dbus
PROCESS_OUTPUT=$(mktemp "${TMPDIR:-/tmp/}$(basename $0).XXX")
dbus-daemon --config-file=/usr/share/dbus-1/system.conf --print-address --nofork &> ${PROCESS_OUTPUT} &
PROCESS_PID=$!
echo -n "waiting for dbus socket: "
until grep -q -i 'unix:path' ${PROCESS_OUTPUT}
    do       
        if ! ps ${PROCESS_PID} > /dev/null 
        then
            echo "The process died" >&2
            exit 1
        fi
        echo -n "."
        sleep 1
    done
echo 
echo "dbus is running!" 
sleep 1

# start Avahi mDNS Daemon in the background
echo "starting avahi daemon..."
avahi-daemon &

# create associative array to store publisher PIDs
declare -A PUBLISHERS
# publishers lock file
LOCK_FILE='/tmp/publishers'
function lock() {
    # acquire lock
    if mkdir "${LOCK_FILE}" &>/dev/null; then
        trap '{ rm -rf ${LOCK_FILE}; }' HUP INT QUIT TERM EXIT
    else
        exit 0
    fi
}

function unlock() {
    rm -rf ${LOCK_FILE}
}

# trap HUP and flush
function flush_mdns() {
    echo "got HUP signal..."
    for KEY in "${!PUBLISHERS[@]}"
    do
        echo "terminating advertisement for ${KEY}"
        kill -s TERM "${PUBLISHERS[${KEY}]}"
    done
}
trap 'flush_mdns' HUP

# starting initial pass and publishing containers
echo "starting initial startup pass..."
curl \
    -s \
    --unix-socket '/run/docker.sock' \
    -H 'Accept: application/json' \
    'http://localhost/containers/json' | jq -r '.[].Names[0]' | sed 's/\///g' | while read -r MDNS_HOST; do

    echo "advertising ${MDNS_HOST}.${MDNS_DOMAIN} as ${POINTER_ADDRESS}"
    avahi-publish -v -a "${MDNS_HOST}.${MDNS_DOMAIN}" -R ${POINTER_ADDRESS} &
    lock
    PUBLISHERS[${MDNS_HOST}]=$!
    unlock
done

# read Docker socket and start or stop publishers with containers
echo -n "waiting for container events: "
curl \
    -s \
    --unix-socket '/run/docker.sock' \
    -H "Accept: application/json" \
    'http://localhost/events' | while read -r EVENT; do
    # build name.local
    echo -n "."
    MDNS_HOST=`echo ${EVENT} | jq -r '.Actor.Attributes.name'`
    if [ -z ${MDNS_HOST} ]; then
        continue
    fi
    case `echo ${EVENT} | jq -r ".status"` in
      "create")
        printf "\n"
        echo "advertising ${MDNS_HOST}.${MDNS_DOMAIN} as ${POINTER_ADDRESS}"
        avahi-publish -v -a "${MDNS_HOST}.${MDNS_DOMAIN}" -R ${POINTER_ADDRESS} &
        lock
        PUBLISHERS[${MDNS_HOST}]=$!
        unlock
        ;;
      "destroy")
        lock
        MDNS_PID=${PUBLISHERS[${MDNS_HOST}]}
        unlock
        printf "\n"
        echo "stopping advertisements for ${MDNS_HOST} running under PID ${MDNS_PID}"
        if [ ! -z "${MDNS_PID}" ]; then
            kill -s TERM "${MDNS_PID}"
        fi
        ;;
    esac
done

echo "bye!"