<?php 
$files = array();
$dir = new DirectoryIterator('.');
foreach ($dir as $fileinfo) {     
   $files[$fileinfo->getMTime()][] = $fileinfo->getFilename();
}

ksort($files);


?>


<?php

$it = new DirectoryIterator(__DIR__);
foreach ($it as $fileinfo) {
  if (!$fileinfo->isDot())
    var_dump($fileinfo->getFilename());
}

$it = new FilesystemIterator(__DIR__);
foreach ($it as $fileinfo) {
  echo $fileinfo->getFilename() . "\n";
}

$iterator = new DirectoryIterator(dirname(__FILE__));
foreach ( $iterator as $fileinfo ) {
    var_dump($fileinfo->current()); // would return object(DirectoryIterator)
}

$iterator = new FilesystemIterator(__DIR__, FilesystemIterator::CURRENT_AS_PATHNAME);
foreach ( $iterator as $fileinfo ) {
    var_dump($iterator->current()) . "\n"; // Would return full path eg /www/examples/example.php
}
?>

<?php

// https://stackoverflow.com/questions/124958/glob-sort-array-of-files-by-last-modified-datetime-stamp

function files_attachment_list($id, $sort_by_date = false, $allowed_extensions = ['png', 'jpg', 'jpeg', 'gif', 'doc', 'docx', 'pdf', 'zip', 'rar', '7z'])
{
    if (empty($id) or !is_dir(sprintf('files/%s/', $id))) {
        return false;
    }
    $out = [];
    foreach (new DirectoryIterator(sprintf('files/%s/', $id)) as $file) {
        if ($file->isFile() == false || !in_array($file->getExtension(), $allowed_extensions)) {
            continue;
        }

        $datetime = new DateTime();
        $datetime->setTimestamp($file->getMTime());
        $out[] = [
            'title' => $file->getFilename(),
            'size' => human_filesize($file->getSize()),
            'modified' => $datetime->format('Y-m-d H:i:s'),
            'extension' => $file->getExtension(),
            'url' => $file->getPathname()
        ];
    }

    $sort_by_date && usort($out, function ($a, $b) {
        return $a['modified'] > $b['modified'];
    });

    return $out;
}

function human_filesize($bytes, $decimals = 2)
{
    $sz = 'BKMGTP';
    $factor = floor((strlen($bytes) - 1) / 3);
    return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) . @$sz[$factor];
}

// returns a file info array from path like '/files/123/*.extensions'
// extensions = 'png', 'jpg', 'jpeg', 'gif', 'doc', 'docx', 'pdf', 'zip', 'rar', '7z'
// OS specific sorting
print_r( files_attachment_list(123) );

// returns a file info array from the folder '/files/456/*.extensions'
// extensions = 'txt', 'zip'
// sorting by modified date (newest first)
print_r( files_attachment_list(456, true, ['txt','zip']) );

?>