# gantt.pm: perl module for doing xhtml/css gantt charts.
package gantt;
use Exporter;
use Date::Calc qw( Day_of_Week Days_in_Month Month_to_Text);
use CGI qw(:standard);

our $VERSION     = 0.4;
our @ISA         = qw(Exporter);
our @EXPORT      = ( qw(gantt_head gantt_tail gantt_task) ); # exports all 3 subs
our @EXPORT_OK   = qw(gantt_head gantt_tail gantt_task);
our %EXPORT_TAGS = ();

my $month,$year,$last_day;
my @this_month = gmtime;
my $today=$this_month[3];

sub gantt_head ($$) {
	($year,$month)=@_;
	my $return="";
	$last_day=Days_in_Month($year,$month);
	$return.=h1(Month_to_Text($month) . " $year") . "\n";
	$return.='<div class="gantt_bdy" style="width:'. (2+($last_day*30)) . 'px;">';
	
	for (my $i = 1; $i <= $last_day; $i++ )  {
		$dow = Day_of_Week($year,$month,$i);
      		$return.='<div class="gantt_head"';
		$return.=' style="background-color:gray"' if ($dow>5 && $i!=$today);
		$return.=' style="background-color:#f00"' if ($i==$today);
		$return.=">$i</div>\n";
	}
	return $return . br();
}

sub gantt_task($$$$$$$$$) {
	return if(!defined $month || !defined $year);
	my $return="";
	my ($start_year,
	    $start_month,
	    $start_day,
	    $stop_year,
	    $stop_month,
	    $stop_day,
	    $name,
	    $url,
	    $priority)=@_;
	@_=();
	if($start_year<$year) {
		$start_year=$year;
		$start_month = $start_day = 1;
	}
	if($stop_year<$year) {
		$stop_year=$year;
		$stop_month = 12;
		$stop_day = 31;
	}
	if($start_month< $month) {
  		$start_month = $month;
		$start_day=1;
	}
	if($stop_month>$month) {
		$stop_month = $month;
		$stop_day = $last_day;
	}
	my $width=  ( ( ($stop_day-$start_day) * 30) + 28);
	$width=28 unless( $width > 27);
	$return.='<div class="gantt_cell_' . $priority;
	$return.='" style="margin-left: ' . (($start_day-1)*30) . 'px;';
	$return.='width: ' . $width . 'px;">';
	$return.=a({-href=>"$url"},"$name");
	$return.="</div>\n";
	return $return;
}


sub gantt_tail {
	return if(!defined $month || !defined $year);
	return("</div>");
}

1;