#!/usr/bin/perl -w

###
# ver 0.5 25 october 2023 Added retry to connect to sqm-le if connection failed
# hansi@htk.se

use IO::Socket;
use Astro::Coord::ECI;
use Astro::Coord::ECI::Sun;
use Astro::Coord::ECI::TLE;
use Astro::Coord::ECI::Utils qw{ :all };

use LWP::Simple qw(get);

$|=1; # Make STDOUT immediate (non-buffered)

my $sqm_ip_addres = '192.168.10.130'; # IP address of your SQM-LE
my $sqm_port = 10001; # port of your SQM-LE (default)
my $lightpollutionmap_key = 'SRwmK5l4wfFNFa3l'; # input your key
my $latitude =  59.0700704;
my $longitude = 16.1881969;
my $max_sun_elevation = -18; # do not read if sun is above this value
my $read_interval = 180; # in seconds
my $retry = 10; # if sqm-le is busy, retry in seconds


while ( 1 ) {
        my $elevation = sunElevation();
        print "Sun elevation ", $elevation, "\n";

        if ( $elevation < $max_sun_elevation ) {
                $sqm = readSQM();
                # if sqm = 0 then we couldnt connect to the meter.
                if ( $sqm != 0 ) {
                        chomp($timeNow = `date -u "+%Y-%m-%dT%H:%M:%S"`);
                        my $url = "https://www.lightpollutionmap.info/sqm/submit.ashx?key=$lightpollutionmap_key&sqm=$sqm&utctime=$timeNow";
                        my $html = get $url;
                        print $url, "\n";
                        print $html, "\n";
                }
        }
        sleep $read_interval;
}

sub readSQM {
        # try 10 times to read the sqm-le device
READ: {
        for ( my $i = 0; $i < 10; $i++ ) {
                my $remote = IO::Socket::INET->new(PeerAddr => $sqm_ip_addres,
                                                PeerPort => $sqm_port,
                                                Proto    => 'tcp');
                if ( ! defined $remote || $remote eq '' ) {
                        print "unable to connect to sqm-le\n";
                        print "i = ", $i, "\n";
                        sleep $retry;
                } else {

                        $remote->autoflush(1);

                        $str="";

                        #-- Send request to remote SQM
                        print $remote "rx";

                        #-- Add response to string
                        $str .= <$remote>;

                        #-- Close remote socket
                        $remote->close;

                        @foo = split(/,/,$str);
                        $sqm = $foo[1];
                        #r, 00.00m,0000566034Hz,0000000000c,0000000.000s, 018.3C
                        print "SQM = ", $sqm, "\n";

                        $sqm =~ s/m//;
                        $sqm =~ s/\s+//;

                        #remove 0.11 for the Waterproof housing window.
                        if ( $sqm > 1.0 ) {
                                $sqm = $sqm - 0.11;
                        }
                        last READ;
                }
        }
}
        return $sqm;
}


sub sunElevation {

#Calculate the Sun elevation

my $lat = deg2rad( $latitude );
my $lon = deg2rad( $longitude );
my $elev = 0;

# Record the time
my $time = time ();

# Set up observer's location
my $loc = Astro::Coord::ECI->geodetic ($lat, $lon, $elev);

# Uncomment to turn off atmospheric refraction if desired.
# $loc->set( refraction => 0 );

# Instantiate the Sun.
my $sun = Astro::Coord::ECI::Sun->universal ($time);

# Figure out if the Sun is up at the observer's location.
my ($azimuth, $elevation, $range) = $loc->azel ($sun);
#print "The Sun is ", rad2deg ($elevation),
#    " degrees above the horizon.\n";

my $elevationDegres = rad2deg ($elevation);
return $elevationDegres;

}