#!/usr/bin/perl 

use Sys::Syslog;
#
# Written by Andrii Grytsenko 2009
#
#Global variables section #1
my $config_file=shift;
my %conf = ();
my $active_node=0;
my $ping_cnt=0;


sub sys_msg {
    my $syslog_level=shift;
    my $message=shift;
    syslog($syslog_level,$message);
}

sub make_sync {
    my $sync_time=shift;
    my $debug=shift;
    $sync_time =~ m/(\d+)(\S+)/;
    my $time_amount=$1;
    my $time_measure=$2;
    my $time_value=0;
    sys_msg("info|$conf{log_facility}","Time amount=$time_amount, Time measure = $time_measure\n") if $debug;
    if ($time_measure eq "min") {
	$time_value=`date +%M`;
    } 
    elsif ($time_measure eq "d") {
	$time_value=`date +%d`;
    }
    elsif ($time_measure eq "h") {
	$time_value=`date +%H`;
    }
    elsif ($time_measure eq "mon") {
	$time_value=`date +%m`;
    } 
    else { 
	sys_msg("info|$conf{log_facility}","Error the time measure is not valid\n");
    }
    chomp($time_value);
    sys_msg("info|$conf{log_facility}","Current time is $time_value\n");
    if ($time_value%$time_amount == 0 ) {
        sys_msg("info|$conf{log_facility}","Try to get actual content from active node\n") if $debug;
	system("/usr/bin/rsync -e ssh -aq rsync\@$conf{another_node_addr}:/var/www/html /var/www/");
    }
}

sub read_config {
    my $conf_file=shift;
    open(CONF,"<$conf_file");
    while(<CONF>) {
	chomp;
	if ( $_ =~ /^([^#].*)=(.*)/ ){
	    $conf{$1}=$2;
	}
    }
    close(CONF);
}

sub check_vars {
    my @vars=("another_node_addr", "virtual_addr", "max_sleep_time", "max_ping_cnt", "log_facility", "sync_time", "debug");
    foreach my $i (@vars) {
	if (!defined($conf{$i})){
	    print "ERROR: variable \"$i\" is not defines at configuration file\n";
	    sys_msg("info|$conf{log_facility}", "ERROR: variable \"$i\" is not defines at configuration file\n"); 
	    exit -1;
	}
    }
}

read_config("$config_file");
check_vars();

# Global variable section #2

my $sleep_time=int(rand($conf{max_sleep_time}));
my $mx_ping_cnt=int(rand($conf{max_ping_cnt}));
my $debug=$conf{debug};


sys_msg("info|$conf{log_facility}", "max ping = $mx_ping_cnt\t sleep = $sleep_time\n") if $debug;
my $cur_addr=`/sbin/ifconfig eth0:1 | grep "addr:" | awk '{print \$2}'  | awk -F: '{print \$2}'`;
chomp($cur_addr);
sys_msg("info|$conf{log_facility}","Current address of virtual ip is $cur_addr\n") if $debug;
if ( "$cur_addr" eq "$conf{virtual_addr}" ){
    $active_node=1;
    sys_msg("info|$conf{log_facility}","set as active node\n") if $debug;
} else {
    my $ping_virt=system("/bin/ping -c1 $conf{virtual_addr} &>/dev/null");
    chomp($ping_virt);
    sys_msg("info|$conf{log_facility}","ping=$ping_virt\n") if $debug;
    while ( $ping_virt != 0 and $ping_cnt <= $mx_ping_cnt ){
        $ping_virt=system("/bin/ping -c1 $conf{virtual_addr} &>/dev/null");
        chomp($ping_virt);
        next if ( $ping_virt == 0) ;
        sys_msg("info|$conf{log_facility}", "ping status is $ping_virt\n");
        sys_msg("info|$conf{log_facility}","Virtual ip $conf{virtual_addr} is free. Sleep $sleep_time seconds; Ping count is $ping_cnt\n") if $debug;
        sleep $sleep_time;
        my $ping_node=system("/bin/ping -c1 $conf{another_node_addr} &>/dev/null");
        chomp($ping_node);
        if ($ping_node != 0 or $ping_cnt == $mx_ping_cnt ){
            system("/sbin/ifconfig eth0:1 $conf{virtual_addr}");
    	    $active_node=1;
	}
        $ping_cnt++;    
    }
}

if ($active_node == 1) {
    sys_msg("info|$conf{log_facility}","this node is active\n") if $debug;
} else {
	sys_msg("info|$conf{log_facility}","this node is passive\n");
	make_sync("$conf{sync_time}", "$conf{debug}");
}