use strict;
use warnings;
package SunEvents;

use Math::Trig;

use constant kTransit      => 0.0;
use constant kOffical      => 90.833333;
use constant kCivil        => 96.0;
use constant kNautical     => 102.0;
use constant kAstronomical => 108.0;


sub new {
    my $class = shift;
    
    my $self = bless {}, $class;
    $self->{zenith} = kOffical;
    $self->{localOffset} = 12.0;
    
    return $self;
}


sub setYMD {
    my ($self, $year, $month, $day) = @_;
    
    @{$self}{'year', 'month', 'day'} = ($year, $month, $day);
}


sub setLatDMS {
    my ($self, $deg, $minute, $second) = @_;
    
    @{$self->{lat}}{'deg', 'minute', 'second'} = ($deg, $minute, $seco
+nd);
    
    ($minute, $second) = (-$minute, -$second) if $deg < 0;
    $self->{latitude} = $deg + ($second / 60.0 + $minute) / 60.0;
}


sub setLongDMS {
    my ($self, $deg, $minute, $second) = @_;
    
    @{$self->{long}}{'deg', 'minute', 'second'} = ($deg, $minute, $sec
+ond);
    $self->{longitude} = $deg + ($second / 60.0 + $minute) / 60.0;
}


sub asHS {
    my $time = shift;
    my $hour = int $time;
    my $min  = int ($time * 60 % 60);
    my $sec = int ($time * 3600 % 60);
    return sprintf "%02d:%02d:%02d", $hour, $min, $sec;
}


sub calcRiseTime {
    return shift->DoCalc (1);
}


sub calcSetTime {
    return shift->DoCalc ();
}


sub calcTransitTime {
    my $self = shift;
    
    return ($self->DoCalc () + $self->DoCalc (1)) / 2.0;
}


sub DoCalc {
    my ($self, $rising) = @_;
    my $N1      = int (275 * $self->{month} / 9);
    my $N2      = int (($self->{month} + 9) / 12);
    my $N3      = (1 + int (($self->{year} - 4 * int ($self->{year} / 
+4) + 2) / 3));
    my $yearDay = $N1 - ($N2 * $N3) + $self->{day} - 30;
    my $longHour = $self->{longitude} / 15.0;       # Convert the long
+itude to hour value
    my $approxTime = $yearDay + ((($rising ? 6.0 : 18.0) - $longHour) 
+/ 24.0);
    my $sunAnomaly = (0.9856 * $approxTime) - 3.289;
    my $sunLong =
      adjRange ($sunAnomaly +
          (1.916 * sinD ($sunAnomaly)) +
          (0.020 * sinD (2 * $sunAnomaly)) +
          282.634);
    my $RA = adjRange (atanD (0.91764 * tanD ($sunLong)));

    # Adjust RA quadrant to match $sunLong and convert to hours
    my $sunLongQuad  = (int ($sunLong / 90)) * 90;
    my $RAquad = (int ($RA / 90)) * 90;

    $RA = ($RA + ($sunLongQuad - $RAquad)) / 15.0;

    my $sunDecSin = 0.39782 * sinD ($sunLong);
    my $sunHACos =
      (cosD ($self->{zenith}) - ($sunDecSin * sinD ($self->{latitude})
+)) /
      (cosD (asinD ($sunDecSin)) * cosD ($self->{latitude}));

    if ($sunHACos > 1) {
        print "No sunrise\n";
        return;
    } elsif ($sunHACos < -1) {
        print "No sunset\n";
        return;
    }

    my $sunHA = ($rising ? 360.0 - acosD ($sunHACos) : acosD ($sunHACo
+s)) / 15.0;
    my $localMeanTime = $sunHA + $RA - (0.06571 * $approxTime) - 6.622
+;
    my $UT = adjRange ($localMeanTime - $longHour, 24.0);
    return adjRange ($UT + $self->{localOffset} + 1 / 120.0, 24.0);
}


sub adjRange {
    my ($value, $limit) = @_;

    $limit ||= 360.0;
    $value -= $limit while $value >= $limit;
    $value += $limit while $value < 0;
    return $value;
}

sub sinD {
    return sin (deg2rad (shift));
}

sub cosD {
    return cos (deg2rad (shift));
}

sub tanD {
    return tan (deg2rad (shift));
}

sub asinD {
    return rad2deg (asin (shift));
}

sub acosD {
    return rad2deg (acos (shift));
}

sub atanD {
    return rad2deg (atan (shift));
}


package main;

use Tk;

my $main = MainWindow->new (-title => "Sun times calculator");

# Date controls
my ($day, $month, $year) = (22, 5, 2008);
my %common = (-padx => 5, -pady => 2, -top => '%0');
my $dayLbl = $main->Label (-text => 'Day:')->
    form (-l => '%0', -r => '%30', %common);
my $dayEnt = $common{-top} = $main->Entry (-textvariable => \$day)->fo
+rm (-l => $dayLbl, %common);
my $monthLbl = $main->Label (-text => 'Month num:')->form (-l => '%0',
+ -r => '%30', %common);
my $monthEnt = $common{-top} = $main->Entry (-textvariable => \$month)
+->form (-l => $monthLbl, %common);
my $yearLbl = $main->Label (-text => 'Year:')->form (-l => '%0', -r =>
+ '%30', %common);
my $yearEnt = $common{-top} = $main->Entry (-textvariable => \$year)->
+form (-l => $yearLbl, %common);

# Latitude controls
my ($latDeg, $latMin, $latSec) = (-44, 42, 5.92); # 44°42'5.92"S
my $latLbl = $main->Label (-text => 'lat (DMS):')->form (-l => '%0', -
+r => '%30', %common);
my $latDegEnt = $main->Entry (-textvariable => \$latDeg)->
    form (-l => $latLbl, -r => ['&', $latLbl, 40], %common);
my $latMinEnt = $main->Entry (-textvariable => \$latMin)->
    form (-l => $latDegEnt, -r => ['&', $latDegEnt, 40], %common);
my $latSecEnt = $common{-top} = $main->Entry (-textvariable => \$latSe
+c)->
    form (-l => $latMinEnt, -r => ['&', $latMinEnt, 56], %common);

# Longitude controls
my ($longDeg, $longMin, $longSec) = (169, 7, 57.13);#169° 7'57.13"E
my $longLbl = $main->Label (-text => 'long (DMS):')->form (-l => '%0',
+ -r => '%30', %common);
my $longDegEnt = $main->Entry (-textvariable => \$longDeg)->
    form (-l => $longLbl, -r => ['&', $longLbl, 40], %common);
my $longMinEnt = $main->Entry (-textvariable => \$longMin)->
    form (-l => $longDegEnt, -r => ['&', $longDegEnt, 40], %common);
my $longSecEnt = $common{-top} = $main->Entry (-textvariable => \$long
+Sec)->
    form (-l => $longMinEnt, -r => ['&', $longMinEnt, 56], %common);

# Calculate controls
my $calc = $main->Button (-text => 'Calculate', -command => \&calculat
+e)->
    form (-l => '%10', %common);
my $result = $main->Label (-relief => 'sunken')->form (-l => $calc, -r
+ => ['&', $calc, 72], %common);

MainLoop ();


sub calculate {
    my $calculator = SunEvents->new ();
    
    $calculator->setYMD ($year, $month, $day);
    $calculator->setLatDMS ($latDeg, $latMin, $latSec);
    $calculator->setLongDMS ($longDeg, $longMin, $longSec);
    $result->configure (-text => SunEvents::asHS ($calculator->calcTra
+nsitTime ()));
}
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