#!/usr/bin/perl -w

## check websites connection.msg you whenever spot
## a difficulty or downtime.
## A cron job should be set too. check every 15minutes.
## -v shows output of prob time. 
## A db file is saved into the directory where
## this perl file exist as default. You should choose 
## a place to save it as saving the config/info file at
## the same place with the exe file is bad !! 

use strict;
use DB_File;
use LWP;

my (%states,$slow_sites,$down_sites,$back_sites);

# turn verbose on which show more info.
my $verbose = 1 if (@ARGV);

my ($path) = `which $0` =~ m#(.*)/#;
my $dbfile = "$path/site_state.db";

tie %states, 'DB_File', $dbfile, O_CREAT|O_RDWR|O_EXCL, 0664;

#my ($day,$mon,$date) = split / /,scalar(localtime);
my %sites = ( 'perl.com' => 'http://www.perl.com',
			  'easyya.com' => 'http://www.easyya.com',
			);

my ($slow,$down) = ('slow','down');
my $br = new LWP::UserAgent;
$br->agent( 'CheckAlive/0.01' );

CHECK: while (my ($site,$url) = each %sites) {
	my ($total,$resp) = request_it( $url );

	# if we fetch the site successfully
	if ($resp->is_success) {
		
		print "request $site ,consumed $total sec\n" if($verbose);
		# take more than 10sec to fetch ? too slow.
		MORE: if ($total > 10) {
			
			# skip if it takes long to acess google, 
			# possibly we have a network problem
			my ($time) = request_it('http://www.google.com');
			next CHECK if ($time > 10);

			# we may want to do a double check-up
			# ($total) = request_it ( $site ); next MORE;

			# case Good connection --> slow connection.
			# case down connection --> slow connection.
			if ( !(exists $states{$site}) || 
			  defined $states{$site} && $states{$site} eq $down) {
				$states{$site} = $slow;
				$slow_sites .= $site." ";
				next CHECK;
			}
			# case ignored.slow connection --> slow connection.

		} else {
			# case good connection --> good connection
			next unless (exists $states{$site});			
			# case down connection --> good connection 
			# case slow connection --> good connection
			# clean server bad record.
			$back_sites .= $site." ";
			delete $states{$site};		
		}
	} else {
		
		# skip if it takes long to acess google, 
		# possibly we have a network problem
		my ($t,$r) = request_it('http://www.google.com');
		next CHECK unless ( $r->is_success );
		
		print "Failed: $site. Consumed $total sec\n" if($verbose);
		# case slow connection --> down connection 
		# case good connection --> down connection 		
		if ( !( exists $states{$site} ) || 
		  defined $states{$site} && $states{$site} eq $slow ) {		
			$states{$site} = $down;
			$down_sites .= $site;
			next CHECK;
		}

		# case ignored.down connection --> down connection
	}	
}

if ($back_sites) {
	send_msg( $back_sites,'come back to work. :)' );
}
if ($slow_sites) {
	send_msg("hmmm..$slow_sites","too slow,maybe a reboot or hotlink?");
}
if ($down_sites) {
	send_msg( $down_sites,'down, please check.' );
}

sub request_it {
	my $start = time();
	my $res = $br->head( $_[0] );
	my $end = time();	
	return ($end-$start, $res);
}

sub send_msg {
	my ( $site,$msg ) = @_;
	print "\nsending server difficulty msg thr icq ....\n";
	`echo "msg james/$site $msg" | /usr/local/bin/vicq -b -o`;
}

untie %states;

__END__

%states is hash in form of 

states = ( site_1 => site_status )