#/bin/sh

################################################################################
#   This daemon monitors the satellite signal info on the given frequency,
# formats the expected output, and sends the status report via UDP to the
# cloud management system.
#
# - Usage:
#     signal_monitor --server_ip=<ip_address> --udp_port=<port>
#                    --dvb_type=<dvbs2|dvbs>
#                   [--freq=<freq>] [--rate=<rate>] [monitor_sec=<sec>]
#
################################################################################

# TODO(hunguyen): remove this customized script when new toybox tool supports
# UDP send for netcat command.
UDP_SEND="/usr/bin/udp_send"

usage() {
  cat <<EOF
usage: signal_monitor [options] ...
options:
  --server_ip                        Required server ip address to send report.
  --udp_port                         Required UDP port to send report.
  --freq=1400000                     Intermediate tuning frequency in kHz
                                     (default = 1400 MHz)
  --rate=30000                       Symbol rate in 1000s (default = 30000)
  --monitor_sec=60                   Monitor interval in seconds.
  --dvb_type=dvbs2                   DVB type (default = dvbs2)
  --help                             Print this usage menu.
EOF
  return 0
}

failmsg() {
  local rval=$?
  echo "FAIL: $0: $* Abort signal monitoring!" 1>&2
  [ ${rval} -ne 0 ] && return ${rval}
  return 1
}

# Parses arguments and ensures required parameters are present.
parse_args() {
  local arg
  opt_freq=1400000
  opt_rate=30000
  opt_interval=60
  opt_server_ip=
  opt_udp_port=
  opt_dvb_type=dvbs2

  # Then parse options.
  while [ $# -ge 1 ]; do
    # Arg starting with dash is formally an option.
    case "$1" in (-*);; (*) break;; esac
    arg=$1
    shift
    case "${arg}" in
      --) break;;
      *help) usage && exit 0;;
      --freq=*) opt_freq=${arg#*=};;
      --rate=*) opt_rate=${arg#*=};;
      --monitor_sec=*) opt_interval=${arg#*=};;
      --server_ip=*) opt_server_ip=${arg#*=};;
      --udp_port=*) opt_udp_port=${arg#*=};;
      --dvb_type=*) opt_dvb_type=${arg#*=};;
      *) failmsg "Unknown option ${arg}; try --help." || return;;
    esac
  done

  # Return failure if required parameters are empty.
  [ -n "${opt_server_ip}" ] ||
    failmsg "Missing required parameter --server_ip; try --help." || return
  [ -n "${opt_udp_port}" ] ||
    failmsg "Missing required parameter --udp_port; try --help." || return
}

main() {
  parse_args "$@" || return

  # Daemon job to monitor satellite signal and send the data to Google prod.
  while [ 1 ]
  do
    # If dvbtune is not already running, start dvbtune for this frequency.
    ps -ef | grep "dvbtune" | grep "${opt_freq}" >/dev/null
    if [ $? -ne 0 ]
    then
      echo "No dvbtune found for this frequency. Starting new dvbtune..."
      # Kill any other dvbtune.
      pkill -9 dvbtune

      # Start new dvbtune with this frequency and rate.
      dvbtune -i ${opt_freq} -r ${opt_rate} -s ${opt_dvb_type} &
      ps -ef | grep " $! " | grep -v grep >/dev/null ||
        failmsg "Failed to start tuner with frequency ${opt_freq}..." ||
        continue
    fi

    # Reaching here means dvbtune is already in place. Start dvbsnoop to gather
    # satellite signal info.
    # Actual dvbsnoop signal output format is:
    #   Sig: 100  SNR: 65517  BER: 0  UBLK: 0  Stat: 0x01
    # Expected format to parse and monitor is:
    #   Ts:123456789 Freq:1400 Sig:100 SNR:65517 BER:0 UBLK:0 Stat:0x01
    # Manipulate the output signal here to the expected format.
    # TODO(hunguyen): Any need to gather frontend info?
    data="Ts:$(date +%s) Freq:$((${opt_freq}/1000)) $(dvbsnoop -s signal -pd 4 \
         -n 1 -hideproginfo | sed '1,5d' | sed 's/: /:/g' | sed 's/ \+/ /g')"

    # Now send the info to event_proxy
    echo "Sending '${data}' to event_proxy..."
    ${UDP_SEND} --hostname "${opt_server_ip}" --port ${opt_udp_port} \
      --data "${data}"

    sleep ${opt_interval}
  done
}

main "$@"