#!/usr/bin/env bash

set -euo pipefail

help() {
  cat <<EOF
Usage: ${0##*/} [-p] [-h] [HOST] PORT

Wait until specified PORT is available on HOST (localhost if HOST ommited).

  -p  print progress every second
  -h  print this help
EOF
}

main() {
  show_progress=""
  while getopts "ph" opt; do
    case "${opt}" in
    p)
      show_progress=t
      ;;
    h)
      help
      exit
      ;;
    *)
      help
      exit 1
      ;;
    esac
  done
  shift $((OPTIND - 1))

  if [ $# -eq 2 ]; then
    host="$1"
    port="$2"
  elif [ $# -eq 1 ]; then
    port="$1"
  else
    echo "No host/port provided"
    help
    exit 1
  fi

  until nc -z "${host:-localhost}" "$port"; do
    [ -n "$show_progress" ] && echo -n .
    sleep 1
  done
}

main "$@"