#!/usr/bin/perl

use strict;
no warnings;

use Net::XMPP::Client;

my $debug = 0;

my $cmd = 'dmesg';
my $history_file = '/var/log/dmesg.db';

sub send_XMPP {
	my $jabber_con = new Net::XMPP::Client();
	$jabber_con->Connect( hostname => 'domain.com' );
	$jabber_con->AuthSend(
							username => 'username',
							password => 'pASsW0rD',
							resource => 'resource'
						 );
	my $msg = new Net::XMPP::Message();
	$msg->SetMessage(
						to => 'somebody@domain.com',
						from => 'this_machine@domain.com',
						type => 'chat',
						body => $_[0]
					);
	$jabber_con->Send( $msg );
	$jabber_con->Disconnect();
}


open DMESG, '-|', $cmd or die "$!";
my @dmesg_lines = <DMESG>;
close DMESG;

my @hist_lines;
if ( -r $history_file ) {
	open HIST, '<', $history_file or die "$!";
	@hist_lines = <HIST>;
	close HIST;
}

my @new_lines;

my $hist_cursor = $#hist_lines;

my $hist_lines_count = scalar @hist_lines;

print "dmesg lines: $#dmesg_lines\n" if $debug;

SCAN_HIST:
for my $idx ( reverse 0..$#dmesg_lines ) {
	if ( $hist_lines_count > 0 ) {
		if (    $dmesg_lines[$idx] =~ m/^\[[\s\t]*(\d+\.\d+)\]\s(.*)$/
			 && $hist_lines[$hist_cursor] =~ m/^\[[\s\t]*(\d+\.\d+)\]\s(.*)$/ ) {

			if ( $dmesg_lines[$idx] eq $hist_lines[$hist_cursor] ) {
				# Deside that changes are finished
				last SCAN_HIST;
			} else {
				push @new_lines, $dmesg_lines[$idx];
			}
		}
	} else {
		print "No history to compare, treating as new record\n" if $debug;
		push @new_lines, $dmesg_lines[$idx];
	}
}

if ( @new_lines > 0 ) {
	print "Writing ",@new_lines+0," lines\n" if $debug;
	open HIST, '>>', $history_file or die "$!";
	foreach my $idx ( reverse 0 .. $#new_lines ) {
		print HIST $new_lines[$idx];
		print $new_lines[$idx] if $debug;
	}
	send_XMPP( join( '', reverse @new_lines) );
} else {
	print "There is no changes\n" if $debug;
}