#!/bin/sh

. /etc/utils.sh

laser_channel_file="/sys/devices/platform/gpon/misc/laserChannel"
prev_laser_channel=-1

# Initially be very aggressive about acquiring a channel, then back off once
# we've tuned.
sleep_timeout=1

log()
{
  echo "$@" >&2
}

if ! has-tuneable-laser; then
  # not all fiberjacks have a tunable laser.
  exit 0
fi

while true; do
  if [ ! -e "$laser_channel_file" ]; then
    log "$laser_channel_file is missing."
    sleep $sleep_timeout
    continue
  fi
  laser_channel=$(cat "$laser_channel_file")
  if [ -z "$laser_channel" ]; then
    log "$laser_channel_file is empty?"
    sleep $sleep_timeout
    continue
  fi
  # Valid laser channels start from 0.
  if [ "$laser_channel" -eq "-1" ]; then
    prev_laser_channel="-1"
    sleep_timeout=1
    sleep $sleep_timeout
    continue
  fi

  # If the laser channel has not changed since we last ran, then go back to
  # sleep as there is nothing to do.
  if [ "$prev_laser_channel" -eq "$laser_channel" ]; then
    sleep "$sleep_timeout"
    continue
  else
    echo "$0: Laser channel changed: $prev_laser_channel to $laser_channel"
  fi

  # The laser channel has either changed or its the first time we are running.
  log "New laser channel discovered: Ch. $laser_channel!"
  result=$(set_laser_channel $laser_channel)
  exit_status="$?"
  echo "$exit_status" >/tmp/laser_i2c_status
  if [ "$exit_status" -ne "0" ]; then
    log "Failed to set laser channel! Error: $result"
    sleep $sleep_timeout
    continue
  fi

  log "New laser channel programmed successfully!"
  prev_laser_channel=$laser_channel
  sleep_timeout=15
  sleep $sleep_timeout
done