#!/bin/sh

. /lib/functions.

LOCK="/tmp/ide.lock"

try_lock(){
  mkdir "$LOCK" || echo "Already running!"
  trap "ir $LOCK" EXIT
}

wifi_kick(){
  local dev="$1" ; shift
  local mac="$1" ; shift
  local bantime="$1" ; shift
  ubus call hostapd.${dev} del_client '{ "addr" : "'${mac}'", "reason" : "assoc toomany", "ban_time" : '${bantime}' }'
}

count_file(){
  echo "/tmp/roam-${1}-${2}"
}

count_get(){
  local fn=$(count_file $@)
  if [ -e "$fn" ] ; then
    touch "$fn"
    cat $fn
  else
     echo 0
  fi
}

count_inc(){
  expr $(count_get $@) + 1 > $(count_file $@)
}

count_dec(){
  $(expr $(count_get $@) - 1) > $(count_file $@)
}

count_rm(){
  local fn=$(count_file $@)
  if [ -e $fn ] ; then
    logger -s -t roamguide "forget" $@
    rm $fn
  fi
}

count_cleanup() {
  local device="$1" ; shift
  local current_time=$(date +%s)
  for file in $(find /tmp -maxdepth 1 -name "roam-${device}-*" -type f ); do
    [ "$(expr "$current_time" - $(date +%s -r $file))" -gt "$forget_time" ] && rm $file
  done
}

client_macs() {
  local dev="$1"
  iw dev "${dev}" station dump | grep Station | sed -e 's/^[^ ]\+ \([0-9a-z:]*\) .*/\1/' 
}

client_tq() {
  local dev="$1"
  local mac="$2"
  iw dev "${dev}" station get "${mac}" | grep "signal avg" | xargs | cut -d' ' -f 3
}

roamguide() {
  local s="$1"
  config_get_bool enabled "$s" 'enabled' 0
  [ $enabled -ne 0 ] || return 0

  config_get device "$s" device
  config_get forget_time "$s" forget_time 600
  config_get bantime_base "$s" bantime_base 500
  config_get bantime_factor "$s" bantime_factor 2375

  for mac in $(client_macs "${device}") ; do
    tq=$(client_tq "${device}" "${mac}")
    level=1
    config_list_foreach "$s" signal roamlevel "${tq}" "${device}" "${mac}"
  done
  count_cleanup ${device}
}

roamlevel(){
  local roam_tq="$1" ; shift
  local tq="$1" ; shift
  local device="$1" ; shift
  local mac="$1" ; shift
  if [ ${tq} -le ${roam_tq} ]; then
    mac_count=$(count_get "${device}" "${mac}")
    if [ $mac_count -lt $level ] ; then
      count_inc ${device} ${mac}
      local bantime=$(expr $bantime_base + $(expr $mac_count \* $mac_count) \* $bantime_factor)
      logger -s -t roamguide "${device}: ban ${mac} ${tq}dBm for ${bantime}ms"
      wifi_kick "${device}" "${mac}" "${bantime}"
      break # quits config_list_foreach
    fi 
  fi
  level=$(expr $level + 1)
}

try_lock
config_load 'roamguide'
config_foreach roamguide 'roamguide'