how to do backup to website in php code

1if (!file_exists('/home/sites/'.$_SERVER['SERVER_NAME'].'/cbitsbackup/')) {
2mkdir('/home/sites/'.$_SERVER['SERVER_NAME'].'/cbitsbackup/', 0777, true);
3}
4$filefront = '/home/sites/'.$_SERVER['SERVER_NAME'].'/cbitsbackup/backup-'.$_SERVER['SERVER_NAME'].'-day1';
5$fileend = '.zip';
6$time = time();
7
8if(file_exists($filefront.$fileend)){
9$file = $filefront.'-'.$time.$fileend;}
10else{$file = $filefront.$fileend;};
11zip_directory('/home/sites/'.$_SERVER['SERVER_NAME'].'/public_html',$file);
12
13
14function zip_directory($source,$tempfile){
15if(!extension_loaded('zip') || !file_exists($source)) return false;
16$zip = new ZipArchive();
17if(!$zip->open($tempfile,ZIPARCHIVE::CREATE)) return false;
18$source = str_replace('\\','/',realpath($source));
19if(is_dir($source) === true){
20    $files = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($source), RecursiveIteratorIterator::SELF_FIRST);
21    foreach($files as $file){
22        $file = str_replace('\\', '/', realpath($file));
23        if(is_dir($file) === true) $zip->addEmptyDir(str_replace($source . '/','', $file . '/'));
24        else if(is_file($file) === true) $zip->addFromString(str_replace($source . '/', '', $file), file_get_contents($file));}}
25elseif(is_file($source) === true) $zip->addFromString(basename($source), file_get_contents($source));
26return $zip->close();}
27