Function - User input string to EN sanitized filename, directory, slug, identifier, etc

dev_script_filter_os_url.php

<?php

// @last https://3v4l.org/iSgi8
// @same http://stackoverflow.com/a/34908708/2418655

// Start sample
$raw_str = '.....&lt;div&gt;&lt;/div&gt;<script></script>&amp; Weiß Göbel 中文百强网File name  %20   %20 %21 %2C Décor  \/.  /. .  z \... y \...... x ./  “This name” is & 462^^ not &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; = that grrrreat -][09]()1234747) საბეჭდი-და-ტიპოგრაფიული';
$fallback_str = 'generated__' . date('Y-m-d_H-m_A');
$bad_extension = '....t&+++a()r.gz[]';

echo str_file($raw_str, '_', $bad_extension, $fallback_str);
// End sample


// Returns filesystem-safe string after cleaning, filtering, and trimming input
function str_file_filter(
	$str,
	$sep = '_',
	$strict = false,
	$trim = 248) {

	$str = strip_tags(htmlspecialchars_decode(strtolower($str))); // lowercase -> decode -> strip tags
	$str = str_replace("%20", ' ', $str); // convert rogue %20 into spaces
	$str = preg_replace("/%[a-z0-9]{1,2}/i", '', $str); // remove hexy things
	$str = str_replace("&nbsp;", ' ', $str); // convert all nbsp into space
	$str = preg_replace("/&#?[a-z0-9]{2,8};/i", '', $str); // remove the other non-tag things
	$str = preg_replace("/\s+/", $sep, $str); // filter multiple spaces
	$str = preg_replace("/\.+/", '.', $str); // filter multiple periods
	$str = preg_replace("/^\.+/", '', $str); // trim leading period

	if ($strict) {
		$str = preg_replace("/([^\w\d\\" . $sep . ".])/", '', $str); // only allow words and digits
	} else {
		$str = preg_replace("/([^\w\d\\" . $sep . "\[\]\(\).])/", '', $str); // allow words, digits, [], and ()
	}

	$str = preg_replace("/\\" . $sep . "+/", $sep, $str); // filter multiple separators
	$str = substr($str, 0, $trim); // trim filename to desired length, note 255 char limit on windows
	
	return $str;
}

// Returns full file name including fallback and extension
function str_file(
	$str,
	$sep = '_',
	$ext = '',
	$default = '',
	$trim = 248) {

	// Run $str and/or $ext through filters to clean up strings
	$str = str_file_filter($str, $sep);
	$ext = '.' . str_file_filter($ext, '', true);

	// Default file name in case all chars are trimmed from $str, then ensure there is an id at tail
	if (empty($str) && empty($default)) {
		$str = 'no_name__' . date('Y-m-d_H-m_A') . '__' . uniqid();
	} elseif (empty($str)) {
		$str = $default;
	}

	// Return completed string
	if (!empty($ext)) {
		return $str . $ext;
	} else {
		return $str;
	}
}