#!/usr/local/bin/perl -w


# SET THE FOLLOWING VARIABLES:
# Format of count file is a $time variable followed by names of all  ads,
# static, text, and rotating.
$mydir = "webvert";
$gotoad = "http://www.glamazon.com/cgi-bin/$mydir/ads.pl";
$baseref = "/home/web/glamazon/cgi-bin/$mydir";
#$adcount = $baseref ."/adcount.txt";
$adbanners = $baseref ."/adbanners.txt";
$rotator  = $baseref ."/rotator.txt";
$ads_dir = $baseref ."/ads";
$logs_dir = $baseref ."/logs";


# DO NOT MODIFY ANYTHING BELOW THIS LINE,
# UNLESS YOU'RE SURE YOU KNOW WHAT YOU'RE DOING!

$exclusive_lock = 2;
$unlock_lock = 8;

#Parse incoming name=value pairs

if ($ENV{'QUERY_STRING'}) {
	@pairs = split(/&/, $ENV{'QUERY_STRING'});
	foreach $pair (@pairs) {
		($name, $value) = split(/=/, $pair);
		$value =~ tr/+/ /;
		$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
		$INPUT{$name} = $value;
		}
}

$gotclick = $INPUT{"gotclick"};
$displayad = $INPUT{"displayad"};  # Name of the ad to display - empty if rotating banner ad.

#Turn off buffering so that output is displayed in correct order.
$cfh = select (STDOUT);
$| = 1;
select ($cfh);
	
# Redirect all of the error messages to STDOUT (i.e the
#    browser).
open (STDERR, ">&STDOUT");
if ($gotclick) { &gotoad; } else { &displayad; }

sub displayad {

   	#Print out the HTML Header if we need it
	print "Content-type: text/html\n\n";
	if ( !$displayad ) {
		# Here's where the banner rotation is done.
		# If $displayad is empty pick an ad to display.
		# Banner file contains names of rotating banners.
	
		open (BANNERS, "<$adbanners");
		seek BANNERS, 0,0;
		@bannernames = <BANNERS>;
		close BANNERS;
		foreach $line (@bannernames) { chop ($line) if ($line =~ /\n$/); }
		foreach $line (@bannernames) { push(@a,$line) if ( ($line  =~ /\S/) && (! &already_clicked($line) ) ) ; }
		@bannernames = @a; 											## filter out the spaces and the ones we have already seen

		if  (! @bannernames) { &print_thanks; exit(0);} 		##none left? we have already clicked them all, exit
			else  { 	
			$displayad = "get one!";																##pick an ad we have not clicked yet
			while (! ( grep(/^$displayad/, @bannernames))) {
					open (ROTATOR, "<$rotator");
			$rotvar = <ROTATOR>;
			close ROTATOR;
					
			$rotvar++;
			if ($rotvar > (@bannernames - 1)) {$rotvar = 0};
			
			open (ROTATOR, ">$rotator") || die "Could not open $rotator\n";
			print ROTATOR $rotvar;
			close ROTATOR;

			if ($bannernames[$rotvar] =~ /\S/) {$displayad = $bannernames[$rotvar]}; 
		}
		}
	}
	
	if (&already_clicked($displayad))  { &print_thanks; exit(0);} 
	else
	{
		#Read in the DISPLAY file
			open (DISPLAY, "+>>$ads_dir/$displayad.txt") || &return_error (500, "Ad Display Error", "Could not open ad file $ads_dir/$displayad.txt.");
	
		&read_display_vars;
		# Increment number of times shown. Write out DISPLAY file. Unlock it.
		$shown++;
		&write_display_vars($displayad);
	
	
	# Print out the tag.
	    if ($text) {
			print STDOUT "<A HREF=\"$gotoad?gotclick=$displayad\" ";
			if ($target) {  print STDOUT "TARGET = \"$target\""; }
			if ($javascript) { print STDOUT $javascript; }
			print STDOUT " >$text</A><BR>\n";
	     }
	
		if ($image) {
			print STDOUT "<A HREF=\"$gotoad?gotclick=$displayad\" ";
			if ($target) {  print STDOUT "TARGET = \"$target\""; }
			if ($javascript) { print STDOUT $javascript; }
			print STDOUT " >\n";
			print STDOUT "<IMG SRC=\"$image\" HEIGHT=$height";
	        print STDOUT " WIDTH=$width  ALT=\"$text\"></A>";
		} 
	} 
	exit(0);

}

sub print_thanks
#Say thank you nice surfer
{
print STDOUT "\<FONT COLOR = \"\#FF00FF\" FACE\=\"Comic Sans MS\"  SIZE\=\0\>Thank You For Clicking My Sponsors\!\<BR\>Type Control\-D to Bookmark My Site\<BR\>Please Visit Me Again Later!\<\/FONT\>\n";
}

# This is called when the user clicks on an ad.
sub gotoad {
	open (DISPLAY, "+>>$ads_dir/$gotclick.txt") || &return_error (500, "Ad Log Error", "Could not open ad file $ads_dir/$filename.txt.");

	&read_display_vars;
	$visits++;
	&logunique;
	&write_display_vars($gotclick);
	print "Location: $url ","\n\n";

	exit(0);
}


sub return_error 
{
	local ($status, $keyword, $message) = @_;
	
	print "Content-type: text/html\n";
	print "Status: $status $keyword\n\n";
	
	print <<End_of_Error;
<HTML>
<HEAD>
	<TITLE>CGI Program Error</TITLE>
</HEAD>
<BODY>
<H1>$keyword</H1>
<HR>$message<HR>
</BODY>
</HTML>

End_of_Error

	exit(1);
}

sub read_display_vars {
	seek DISPLAY, 0,0;
	@lines = <DISPLAY>;
	chomp @lines;
	# Name each of the variables in the DISPLAY file.
	($shown,$visits,$uniques,$cents,$url,$text,$image,$height,$width,$target,$javascript,$statsurl,$userid,$passcode,$bannersurl ) = @lines;
}

sub write_display_vars {
	local ($filename) = @_;
		$myfile = "$ads_dir/".$filename.".txt";
		
 		seek DISPLAY, 0, 0; # rewind 

		truncate $myfile, 0; # empty the file 
 
		print DISPLAY "$shown\n";
		print DISPLAY "$visits\n";
		print DISPLAY "$uniques\n";
		print DISPLAY "$cents\n";
		print DISPLAY "$url\n";
		print DISPLAY "$text\n";
		print DISPLAY "$image\n";
		print DISPLAY "$height\n";
		print DISPLAY "$width\n";
		print DISPLAY "$target\n";
		print DISPLAY "$javascript\n";
		print DISPLAY "$statsurl\n";
		print DISPLAY "$userid\n";
		print DISPLAY "$passcode\n";
		print DISPLAY "$bannersurl\n";
		close DISPLAY;
	}

sub logunique {

	$ip_addr = "$ENV{'REMOTE_HOST'}";
	$referer = $ENV{'HTTP_REFERER'};

	$numdate = time(); 
	##$hrs = 48;
	##$cutoff = $numdate - ($hrs * 3600);

	$logfile =  "$logs_dir/$gotclick.log";

	
	if (! (-e $logfile)) {  	#if the logfile doesn't exist, it must be created.
		if (open (LOG, ">" . $logfile)) { 
			flock (LOG, $exclusive_lock);
                	
			# Print IP address & time & referer for each unique hit
			$uniques++;
            print (LOG "$ip_addr $numdate $referer\n");
			flock (LOG, $unlock_lock);
			close (LOG);
			if (! (chmod 0666, $logfile) ) { &return_error (500, "Ad Log Error", "Cannot chmod log file."); }
			} else {
			&return_error (500, "Ad Log Error", "Cannot create log file.");
			}
		} else {		#if the logfile exists
			if (! ((-r $logfile) && (-w $logfile)) ) {
				&return_error (500, "Ad Log Error", "Cannot read or write log file $logfile");
			} else {

				# Read through the log, looking for another hit 
				open (LOG, "+>>" . $logfile);
				flock (LOG, $exclusive_lock);
				seek LOG, 0, 0;
				@content = <LOG>;
					
				# Print IP address for hit only if it's unique (and eventually not recent)
				if ( not (grep  /^$ip_addr/, @content)) {
					$uniques++;
					seek LOG, 2, 0; #@ end of log
					print LOG "$ip_addr $numdate $referer\n";
				}
				close LOG;

			}
		}
}# end sub

sub already_clicked
 { 
	# returns true if this visitor clicked on this ad before

	local ($filename) = @_;
	$ip_addr = "$ENV{'REMOTE_HOST'}";
	$logfile =  "$logs_dir/$filename.log";
	if ( !((-e $logfile) && (-r $logfile)) ) { &return_error (500, "Ad Log Error", "Cannot read log file $logfile $!.");}
	else {
		# Read through the log, looking for another hit 
		open (LOG, "<" . $logfile);
		seek LOG, 0, 0;
		@loglines = <LOG>;
		close LOG;
		foreach $line ( @loglines ) { 
			if ($line =~ /^$ip_addr/) {  return 1; }
		 }
	} 
}	# end sub