HTML Purifier Helper for TinyMCE

text_helper.php

<?php
/**
 * @param string $content
 *
 * @return string
 */
function purify(string $content) : string
{
	$config = \HTMLPurifier_Config::createDefault();
	$config->set('HTML.AllowedElements', [
		'a',
		'b',
		'blockquote',
		'br',
		'code',
		'em',
		'h1',
		'h2',
		'h3',
		'h4',
		'h5',
		'h6',
		'hr',
		'i',
		'img',
		'li',
		'ol',
		'p',
		'pre',
		's',
		'span',
		'strong',
		'sub',
		'sup',
		'table',
		'tbody',
		'td',
		'th',
		'thead',
		'tr',
		'u',
		'ul',
	]);
	$config->set('CSS.AllowedProperties', [
		'color',
		'background-color',
		'font-size',
		'font-weight',
		'padding-left',
		'text-align',
		'text-decoration',
	]);
	$config->set('Attr.AllowedClasses', [
		'alert',
		'alert-danger',
		'alert-info',
		'alert-success',
		'alert-warning',
		'blockquote',
		'blockquote-footer',
		'img-responsive',
		'table',
		'table-bordered',
		'table-condensed',
		'table-hover',
		'table-responsive',
		'table-striped',
	]);
	$config->set('Attr.AllowedFrameTargets', [
		'_blank',
	]);
	$config->set('HTML.AllowedAttributes', [
		'a.href',
		'a.target',
		'code.class',
		'img.class',
		'img.src',
		'ol.start',
		'p.class',
		'p.style',
		'span.style',
		'table.class',
		'td.align',
		'th.align',
	]);
	$config->set('URI.AllowedSchemes', [
		'http' => true,
		'https' => true,
	]);
	return (new \HTMLPurifier())->purify($content, $config);
}