#!/usr/bin/env bash
set -euo pipefail
TARGET_URL="http://192.168.99.183:9090/-/healthy"
EXPECT="Healthy"
NTFY_URL="${NTFY_URL:?}"          # from EnvironmentFile
NTFY_TOKEN="${NTFY_TOKEN:-}"
THRESHOLD=3                        # consecutive fails before first page (~3 min)
RESEND_EVERY=30                    # re-page every N checks while still down
TIMEOUT=10
STATE_DIR="/var/lib/prom-watchdog"; STATE="$STATE_DIR/state"
mkdir -p "$STATE_DIR"
read -r FAILS ALERTED 2>/dev/null < "$STATE" || { FAILS=0; ALERTED=0; }
notify() {  # $1=priority $2=tags $3=title $4=message
  local a=(-s -H "Priority: $1" -H "Tags: $2" -H "Title: $3" -d "$4")
  [ -n "$NTFY_TOKEN" ] && a+=(-H "Authorization: Bearer $NTFY_TOKEN")
  curl "${a[@]}" "$NTFY_URL" >/dev/null 2>&1 || true
}
if curl -fsS --max-time "$TIMEOUT" "$TARGET_URL" 2>/dev/null | grep -q "$EXPECT"; then
  [ "$ALERTED" -eq 1 ] && notify 4 white_check_mark "Prometheus recovered" \
    "media-server Prometheus responding again (off-host watchdog)."
  echo "0 0" > "$STATE"; exit 0
fi
FAILS=$((FAILS + 1))
if [ "$ALERTED" -eq 0 ] && [ "$FAILS" -ge "$THRESHOLD" ]; then
  notify 5 "rotating_light,skull" "Prometheus DOWN (off-host watchdog)" \
    "Pi cannot reach Prometheus at $TARGET_URL after $FAILS checks. media-server may be down or prometheus stopped. ALERTING IS BLIND until resolved."
  ALERTED=1
elif [ "$ALERTED" -eq 1 ] && [ $((FAILS % RESEND_EVERY)) -eq 0 ]; then
  notify 5 rotating_light "Prometheus STILL down" "Unreachable ~${FAILS} min."
fi
echo "$FAILS $ALERTED" > "$STATE"; exit 0