#!/bin/sh
set -eu

WATCH_CONTAINER="${WATCH_CONTAINER:?set WATCH_CONTAINER to the container name or id to watch}"
RESTART_CONTAINERS="${RESTART_CONTAINERS:?set RESTART_CONTAINERS to a comma-separated list of containers to restart}"
POLL_INTERVAL="${POLL_INTERVAL:-30}"
RESTART_DELAY="${RESTART_DELAY:-0}"

# Only restart when status *becomes* unhealthy (avoids restarting every poll while still unhealthy).
# Set RESTART_ON_EVERY_POLL=1 to restart on every poll while unhealthy.
RESTART_ON_EVERY_POLL="${RESTART_ON_EVERY_POLL:-0}"

log() {
  printf '%s %s\n' "$(date '+%Y-%m-%dT%H:%M:%S')" "$*"
}

inspect_health() {
  docker inspect --format '{{if .State.Health}}{{.State.Health.Status}}{{else}}none{{end}}' "$1" 2>/dev/null || printf 'missing'
}

restart_list() (
  IFS=','
  for c in $RESTART_CONTAINERS; do
    c=$(echo "$c" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
    [ -z "$c" ] && continue
    if docker restart "$c" 2>/dev/null; then
      log "restarted: $c"
    else
      log "restart failed: $c"
    fi
    if [ "$RESTART_DELAY" != "0" ]; then
      sleep "$RESTART_DELAY"
    fi
  done
)

prev=""
log "watching health of: $WATCH_CONTAINER (interval ${POLL_INTERVAL}s)"
log "will restart on unhealthy: $RESTART_CONTAINERS"

while true; do
  status="$(inspect_health "$WATCH_CONTAINER")"
  log "health status: $WATCH_CONTAINER = $status"

  case "$status" in
    missing)
      log "watch target not found: $WATCH_CONTAINER"
      ;;
    unhealthy)
      if [ "$RESTART_ON_EVERY_POLL" = "1" ] || [ "$prev" != "unhealthy" ]; then
        log "unhealthy — restarting configured containers"
        restart_list
      fi
      ;;
    *)
      ;;
  esac

  prev="$status"
  sleep "$POLL_INTERVAL"
done