#! /usr/bin/perl
#-------------------------------------------------------
# SECTION 1:
#
# Set variables for the locations and names of all the
# files.
#-------------------------------------------------------
$logfile = "/var/httpd/logs/access_log";
$httproot = "/var/httpd/htdocs/";
$imagedir = "images";
$datafile = "/tmp/gnuplot_$$.dat";
$gpfile = "/tmp/gnuplot_$$.gp";
$giffile = "gnuplot_$$.gif";
$GNUPLOT = "gnuplot";
$PPMTOGIF = "ppmtogif";

#-------------------------------------------------------
# SECTION 2:
#
# Get today's date in the same format as the server's
# access log.
#-------------------------------------------------------

if ($ENV{"QUERY_STRING"} =~ /[0-9]+/) {
    ($day, $mon, $year) = split ("/", $ENV{"QUERY_STRING"});
}
else {
    $datestr = `date`;
    chop $datestr;
    ($dow, $mon, $day, $hour, 
     $min, $sec, $zone, $year) = split (/[ ]+|:/, $datestr);
}
$date = sprintf ("%02d/%s/%d", $day, $mon, $year);

#-------------------------------------------------------
# SECTION 3:
#
# Count the number of hits for the specified date.
#
# I scale minutes (0..59) to a value in the 0..99 range 
# so that gnuplot plots a contiguous graph. For example,
# the time 1:30pm would become the gnuplot x value 1350
# (more or less).
#-------------------------------------------------------
open (LOGFILE, "<\<> $logfile");
while (<\<>LOGFILE>) {
    if ($_ =~ /\[$date/) {
	if ($_ =~ m/^.+\[(.+)\].+$/) {
	    ($indate, $inhour, 
	     $inmin, $stuff) = split (":", $1);
	    $hr_percent = ($inmin/60) * 100;
	    $accesses[$inhour * 100 + $hr_percent]++;
	    $total++;
	}
    }
}
close LOGFILE;

#-------------------------------------------------------
# SECTION 4:
#
# Write the data file that gnuplot will use. 
#-------------------------------------------------------
open (DATAFILE, "> $datafile");
for ($i=0; $i <\<>= 2400; $i++) {
    if (defined ($accesses[$i])) {
	printf (DATAFILE "%04d\t%d\n", $i, $accesses[$i]);
    }
    else {
	printf (DATAFILE "%04d\t0\n", $i);
    }
}
close DATAFILE;

#-------------------------------------------------------
# SECTION 5:
#
# Write the gnuplot command file.
#-------------------------------------------------------

# Define custom tic marks for the x axis.
for ($i=0; $i <\<>=24; $i++) {
    if ($i == 12) {
        $xtics = sprintf ("%s\"%s\" %d,", 
			  $xtics, "Noon", $i*100);
    }
    else {
        $xtics = sprintf ("%s\"%02d\" %d,", 
			  $xtics, $i, $i*100);
    }
}
chop $xtics;

open (GPFILE, "> $gpfile");

# Everything after the following line up to the
# terminating "EOM" line defines the contents of
# the gnuplot command file.
print GPFILE <\<><\<>EOM;
set term pbm color
set offsets
set nolog
set nopolar
set border
set grid

set title "Web Server Accesses for $mon $day, $year"
set xlabel "Time (Hours)"
set ylabel "Number of Hits"
set size 1.10, 0.50
set xtics ($xtics)

plot '$datafile' title "" with lines
EOM

close GPFILE;

#-------------------------------------------------------
# SECTION 6:
#
# Run gnuplot, and convert the output to gif format.
#-------------------------------------------------------
system ("$GNUPLOT $gpfile | $PPMTOGIF 2> /dev/null > "
	."$httproot/$imagedir/$giffile"); 
unlink ($gpfile, $datafile);

#-------------------------------------------------------
# SECTION 7:
#
# Output an HTML page to display the graphic we just
# generated.
#-------------------------------------------------------
print "Content-type: text/html\n\n";
print <\<><\<>EOM;
<\<>HTML>
<\<>BODY bgcolor=#FFFFFF>
<\<>TITLE>Web Access<\<>/TITLE>
<\<>h3>Web Accesses<\<>/h3>
Total Accesses: <\<>b>$total<\<>/b><\<>p>
<\<>IMG SRC=/$imagedir/$giffile><\<>p>
<\<>/BODY>
<\<>/HTML>

EOM