#!/usr/bin/perl
# GPL V2 or greater
# Used to control the 4 led's on ubiquti for device aiming.
# Written by Conrad Lara KG6JEI



sub aimmode_printusage{
   print "USAGE:\n";
   print "$0 SSID\n";
   die;
}


# SSID NAME
if ( $ARGV[0] ) {
    $SSIDName= lc $ARGV[0];
}
else
{
    $SSIDName= lc "SDWG-MESH";
}


$lastset=0;
$lastval=0;


#dbm values for each RSSI trigger level
$RSSI_4=-45;
$RSSI_3=-55;
$RSSI_2=-65;
$RSSI_1=-75;

# LED Set Wrappe
sub SetLED {
    ($fh, $state ) = @_ ;
    print $fh $state ;
    binmode($fh);
}


# Reset LED's to baseline 
sub init_led_triggers {

    open ( LINK4_trigger,'>/sys/class/leds/ubnt:green:link4/trigger');
    open ( LINK3_trigger,'>/sys/class/leds/ubnt:green:link3/trigger');
    open ( LINK2_trigger,'>/sys/class/leds/ubnt:orange:link2/tigger');
    open ( LINK1_trigger,'>/sys/class/leds/ubnt:red:link1/trigger');

    print LINK4_trigger "none";
    print LINK3_trigger "none";
    print LINK2_trigger "none";
    print LINK1_trigger "none";

    close ( LINK4_trigger);
    close ( LINK3_trigger);
    close ( LINK2_trigger);
    close ( LINK1_trigger);

}

sub aimmode_start {

    # Prep the system
    system('/etc/init.d/linkled stop');
    system('/etc/init.d/olsrd stop');
    system('/sbin/ifconfig wlan0 down');
    system('/usr/sbin/iw phy phy0 interface add mon0 type monitor');
    system('/usr/sbin/iw dev mon0 set channel 1');
    system('/sbin/ifconfig mon0 up');
    #Open up the files we will need to run with
    # Run tcpdump in buffered (-l) mode so each line returns with a newline
    open ( $TCPDUMP,"/usr/sbin/tcpdump -l -i mon0 \"link[0] == 0x80\" |");
    open ( $LINK4_led,'>/sys/class/leds/ubnt:green:link4/brightness');
    open ( $LINK3_led,'>/sys/class/leds/ubnt:green:link3/brightness');
    open ( $LINK2_led,'>/sys/class/leds/ubnt:orange:link2/brightness');
    open ( $LINK1_led,'>/sys/class/leds/ubnt:red:link1/brightness');
    

}
sub aimmode_shutdown {

    #Turn off all LED's except LINk4

    SetLED ($LINK4_led, 1);
    SetLED ($LINK3_led, 0);
    SetLED ($LINK2_led, 0);
    SetLED ($LINK1_led, 0);

    close ($TCPDUMP);
    close ($LINK4_led);
    close ($LINK3_led);
    close ($LINK2_led);
    close ($LINK1_led);
    # Brining up wifi is a bit more complicated than just ifconfig up so we let `wifi` handle it ... Wifi takes a bit to finish so sleep 10s
    system('/sbin/wifi'); 
    print "Please wait while we restart the services";
    sleep 10;
    system('/etc/init.d/olsrd start');
    system('/etc/init.d/linkled start');
}

init_led_triggers();

$SIG{INT} = sub { aimmode_shutdown(); exit; };


aimmode_start();

# Main while loop
while ( <$TCPDUMP> )
{
    next unless /.* ([\d\-]+)dB.*Beacon \((.*)\)/;
    next unless lc $2 eq $SSIDName ;

    #Average the last value and this values in order to tame sudden spikes                                                        
    $s=int(($1+$lastvalue)/2);
    print "$s \n";

    if ($s >= $RSSI_4 ) {
        SetLED ($LINK4_led, 1);
    }
    else
    {
        SetLED ($LINK4_led, 0);
    }

    if ($s >= $RSSI_3 ) {
        SetLED ($LINK3_led, 1);
    }
    else
    {
        SetLED ($LINK3_led, 0);
    }

    if ($s >= $RSSI_2 ) {
        SetLED ($LINK2_led, 1);
    }
    else
    {
        SetLED ($LINK2_led, 0);
    }

    if ($s >= $RSSI_1 ) {
        SetLED ($LINK1_led, 1);
    }
    else
    {
        SetLED ($LINK1_led, 0);
    }


    $lastvalue=$s;

}

# Normally the SIG{INT} handler will be done before here
# But in case the TCPDUMP dies out we want to reset the system
aimmode_shutdown();