#!/usr/bin/perl

# WebPage WatchDog (WPWD)
# Author: Oliver Gerards (ogerards@cc86.org)
#
# v1.0, 05.04.2002 (original version)
# v1.1, 06.04.2002 (additional check for empty lines in config file)
#
# This script should be called as a cron job.
# It will check all URLs specified by a user in a .wpwd file in his home 
# directory. If the corresponding web page has changed, the user is notified
# by mail.
#
# Each new entry in the config file must be in a separate line and should have
# the following form:
# URL|0  (the URL followed by a pipe character and a zero)
#   e.g.  http://www.cc86.org/|0

use LWP::Simple;
use Mail::Mailer;

$domain = "cc86.org";   # you may want to change this to your domain
$cfgname = ".wpwd";     # the name of the config file

# find all config files
open CFGFILES, "find /home -name $cfgname |";
foreach $cfgfile ( <CFGFILES> )
{
    chomp $cfgfile;
    $cfgfile =~ /^\/home\/(.*)\/.*$/i;
    my $user = $1;

    print "[WPWD] Processing '$cfgfile': ";
	
    my $errurls = "";
    my $errcount = 0;
    my ($url, %Date);        # hash containing dates of web pages
    my ($url, %StoredDate);  # hash containing locally stored dates of web pages
    my $err = 0;

    open CONFIGFILE, "<$cfgfile"  or $err = 1;

    if ($err == 1)
    {
        print "failed\n";
        next;
    }

    # read config file
    while ( <CONFIGFILE> )
    {
        chomp;
        if (length $_ > 1)
        {
            my ($url, $value) = split(/\s*\|\s*/, $_, 2);
            $StoredDate{$url} = $value;
        }
    }

    close CONFIGFILE;

    # get last modification dates for all URLs
    foreach $url ( keys %StoredDate )
    {
        $err = 0;
        @header = head($url)   or $err = 1;
        if ($err == 0)
        {            
            $Date{$url} = $header[2] || -1;  # unknown
        }
        else
        {
            # an error occured when opening this URL
            $errurls .= $url."\n";
            $errcount++;
        }
    }

    my $count = 0;
    my $changedurls = "";

    # compare all dates, add corresponding URL to string if date has changed
    foreach $url ( keys %Date )
    {
        if ( $Date{$url} > $StoredDate{$url} )
        {
            $changedurls .= $url."\n";
            $count++;

            $StoredDate{$url} = $Date{$url};
        }
    }

    if ($count != 0)
    {
        # create notification mail...
        if ($count > 1)
        {
            $body = "Die folgenden Webseiten haben";
        }
        else
        {
            $body = "Die folgende Webseite hat";
        }
        $body .= " sich geändert:\n\n$changedurls\n\n";
        if ($errcount > 0)
        {
            $body .= "Die folgende(n) URL(s) konnte(n) nicht gecheckt werden:\n\n$errurls\n";
        }
        $body .= "---\n";

        # ...and send it
        $mailer = Mail::Mailer->new();
        $mailer->open({ From    => "wpwd@$domain",
                        To      => "$user@$domain",
                        Subject => "WPWD-Benachrichtigung",
                      })
                    or die "Fatal Error! Can't open: $!\n";
        print $mailer $body;
        $mailer->close();

        # write changes to config file
        open CONFIGFILE, ">$cfgfile";
        print CONFIGFILE map { "$_|$StoredDate{$_}\n" } keys %StoredDate; 
        close CONFIGFILE;
    }
    print "done\n";
}

close CFGFILES;
#
# <EOF>