#!/usr/bin/env bash
# Publishes a service-failed MQTT notification when called by systemd OnFailure=.
# Usage: infoscreen-notify-failure.sh <failing-unit-name>
#
# Designed to be called from infoscreen-notify-failure@.service.
# Reads broker credentials from .env; reads client UUID from config.
# Safe to run even if MQTT is unreachable (exits cleanly, errors logged to journal).

set -euo pipefail

FAILING_UNIT="${1:-unknown}"
PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
ENV_FILE="$PROJECT_DIR/.env"
UUID_FILE="$PROJECT_DIR/src/config/client_uuid.txt"

# Load .env (skip comments and blank lines)
if [[ -f "$ENV_FILE" ]]; then
    set -a
    # shellcheck source=/dev/null
    source <(grep -v '^\s*#' "$ENV_FILE" | grep -v '^\s*$')
    set +a
fi

MQTT_BROKER="${MQTT_BROKER:-localhost}"
MQTT_PORT="${MQTT_PORT:-1883}"
MQTT_USER="${MQTT_USER:-}"
MQTT_PASSWORD_BROKER="${MQTT_PASSWORD_BROKER:-}"

CLIENT_UUID="unknown"
if [[ -f "$UUID_FILE" ]]; then
    CLIENT_UUID="$(cat "$UUID_FILE" | tr -d '[:space:]')"
fi

TOPIC="infoscreen/${CLIENT_UUID}/service_failed"
TIMESTAMP="$(date -u +%Y-%m-%dT%H:%M:%SZ)"

PAYLOAD=$(printf '{"event":"service_failed","unit":"%s","client_uuid":"%s","failed_at":"%s"}' \
    "$FAILING_UNIT" "$CLIENT_UUID" "$TIMESTAMP")

# Build mosquitto_pub auth args
AUTH_ARGS=()
if [[ -n "$MQTT_USER" ]];             then AUTH_ARGS+=(-u "$MQTT_USER"); fi
if [[ -n "$MQTT_PASSWORD_BROKER" ]];  then AUTH_ARGS+=(-P "$MQTT_PASSWORD_BROKER"); fi

echo "Publishing service-failed notification: unit=$FAILING_UNIT client=$CLIENT_UUID"

mosquitto_pub \
    -h "$MQTT_BROKER" \
    -p "$MQTT_PORT" \
    "${AUTH_ARGS[@]}" \
    -t "$TOPIC" \
    -m "$PAYLOAD" \
    -q 1 \
    --retain \
    2>&1 || echo "WARNING: mosquitto_pub failed (broker unreachable?); notification not delivered"