#!/usr/bin/perl
# 1. the getopts ( -u <user> )
# 2. the update usage()
# 3. modify rsync command so we get understand


# our needed packages
use strict "vars";
use Getopt::Std;

# Global Variables 
my $VERBOSE = 0;
my $DEBUG = 0;

# commandline options
# -D <remote_directories
# -H <remote_host>
# -l <local_backup_folder>

my $opt_string = "vdhD:H:l:su:";
getopts( "$opt_string", \my %opt) or usage() and exit(1);

$VERBOSE = 1 if $opt{'v'};
$DEBUG = 1 if $opt{'d'};
if ( $opt{'h'} ){
    usage();
    exit 0;
}
my $HOST = $opt{H};
my $DIR = $opt{D};
my $LOCAL = $opt{l};
my $SIMULATE = $opt{s};
my $USER = $opt{u};

my $ITERATIONS = 3;
usage() and die("you need to supply a hostname\n") unless $HOST; 
usage() and die("you need to supply a remote directory\n") unless $DIR;

$LOCAL = $HOST unless $LOCAL;
debug("Checking if host is up and folder is present\n");
die("The remote host could not verify the directory $DIR or is down. Exiting.\n") unless verify_host($HOST,$DIR,$USER);

    
##########################################################
# main part

# remove the oldest if number equals $ITERATIONS

my $oldest = $LOCAL . "." . $ITERATIONS;
verbose("Removing oldest directory: $oldest\n");
if ( stat($oldest)){
    system("rm -rf $oldest") unless $SIMULATE;
} else {
    debug("Directory $oldest missing, skipping delete\n");
}

# rotate the folders from 1 until the end, backwards

for ( my $i = ( $ITERATIONS -1); $i >= 1; $i--){
    my $new = $LOCAL . "." . ($i + 1);
    my $old = $LOCAL . "." . $i;
    my $command = "mv $old $new";
    debug("Moving directories"); 
if ( stat($old)){
    system("$command") unless $SIMULATE;
}
}

# copy with hard links base folder to .1
my $command = "cp -al " . $LOCAL . " " . $LOCAL . ".1";
debug("Executing: $command\n");
if ( stat($LOCAL)){
system("$command") unless $SIMULATE;
}

# execute rsync
$USER = $USER . "@" if $USER;
my $command = "rsync -a -v --delete -e ssh " . $USER . $HOST . ":" . $DIR . " " . $LOCAL;
debug("Executing rsync: $command\n");
system("$command") unless $SIMULATE; 
    
debug("script is finished, exiting...\n");
exit 0;
    
##################################################
sub usage {
    print "usage:\n";
    print "-h for help\n";
    print "-v for verbose ( more output )\n";
    print "-d for debug ( even more output)\n";
    print "-D <remote_dir> for remote directories\n";
    print "-H <hostname>for remote host\n";
    print "-l <local_dir>local backup folder\n";
    print "-s simulate only , do not execute\n";
    print "-u <username> for the remote user\n";
}

sub verbose {
    print "VERBOSE: " . $_[0] if ( $VERBOSE or $DEBUG );
}    
sub debug {
    print "DEBUG: " . $_[0] if ( $DEBUG );
}    
     
sub verify_host {
    
    my $host = $_[0];
    my $dir = $_[1];
    my $user = $_[2];
    
    $host = $user . "@" . $host if $user;
    open(SSH,"ssh $host stat $dir |");
    while ( my $line = <SSH> ){
	if ( $line =~ /Modify: / ){
	    close(SSH);
	    return 1;
}
	}
    close(SSH);
    return 0;
    
}