#!/bin/sh

CHECK_PERIOD=1
TOTAL_PERIOD=60
LOG_ID="ubios-udapi-server-wait-init"

# @brief Logs error.
#
# @param 1 - The error message.
function log_error() {
  logger -s -t ${LOG_ID} -p 3 "${@}"
}

# @brief Logs info message.
#
# @param 1 - The info message.
function log_info() {
  logger -t ${LOG_ID} "${@}"
}

# @brief Measures how long it takes to execute the passed command.
#        The exit status is that of command.
# @param 1 - The command to execute.
# @return The command execution time in traditional format.
# @example
# Command exited with non-zero status 255
# real 0.09
# user 0.06
# sys 0.03
function measure_cmd_time() {
  time -f '%e' -p "${@}" 2>&1
}

# @brief Parses real time from traditional format.
# @param 1 - The measured time in the traditional format.
# @return The real time.
function parse_real_time() {
  echo "${@}" | grep real | awk '{ print $2 }'
}

# @brief Waits until UUS is up and running
function start() {
  printf "Waiting until ubios-udapi-server is up and running: "

  local ec=1
  for i in $(seq ${CHECK_PERIOD} ${CHECK_PERIOD} ${TOTAL_PERIOD}); do
    local trad_time=""
    local real_time=0
    local sleep_period=${CHECK_PERIOD}

    # issue UDAPI request; UUS is up and running if it succeeds
    trad_time=$(measure_cmd_time /bin/sh -c "/usr/bin/ubios-udapi-client -t ${CHECK_PERIOD} GET -r /server > /dev/null 2>&1")
    ec=$?
    [ "${ec}" -eq 0 ] && break

    # introduce throttling; ubios-udapi-client can respond immediately if the server socket doesn't exist
    real_time=$(parse_real_time "${trad_time}")
    sleep_period=$(echo "${sleep_period} - ${real_time}" | bc)
    sleep_period=$([ $(echo "${sleep_period} < 0" | bc) -eq 1 ] && echo 0 || echo ${sleep_period})

    printf "."
    sleep ${sleep_period}
  done

  if [ "${ec}" -eq 0 ]; then
    echo "OK"
    log_info "ubios-udapi-server is up and running"
  else
    echo "FAIL"
    log_error "ubios-udapi-server hasn't started in the period of ${TOTAL_PERIOD} seconds"
  fi
}

case "$1" in
  start)
        start
        ;;
  stop)
        ;;
  restart|reload)
        start
        ;;
  *)
        echo "Usage: $0 {start|stop|restart}"
        exit 1
esac

exit $?