/home/kueuepay/public_html/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/HTML/ID.php
<?php

/**
 * Validates the HTML attribute ID.
 * @warning Even though this is the id processor, it
 *          will ignore the directive Attr:IDBlacklist, since it will only
 *          go according to the ID accumulator. Since the accumulator is
 *          automatically generated, it will have already absorbed the
 *          blacklist. If you're hacking around, make sure you use load()!
 */

class HTMLPurifier_AttrDef_HTML_ID extends HTMLPurifier_AttrDef
{

    // selector is NOT a valid thing to use for IDREFs, because IDREFs
    // *must* target IDs that exist, whereas selector #ids do not.

    /**
     * Determines whether or not we're validating an ID in a CSS
     * selector context.
     * @type bool
     */
    protected $selector;

    /**
     * @param bool $selector
     */
    public function __construct($selector = false)
    {
        $this->selector = $selector;
    }

    /**
     * @param string $id
     * @param HTMLPurifier_Config $config
     * @param HTMLPurifier_Context $context
     * @return bool|string
     */
    public function validate($id, $config, $context)
    {
        if (!$this->selector && !$config->get('Attr.EnableID')) {
            return false;
        }

        $id = trim($id); // trim it first

        if ($id === '') {
            return false;
        }

        $prefix = $config->get('Attr.IDPrefix');
        if ($prefix !== '') {
            $prefix .= $config->get('Attr.IDPrefixLocal');
            // prevent re-appending the prefix
            if (strpos($id, $prefix) !== 0) {
                $id = $prefix . $id;
            }
        } elseif ($config->get('Attr.IDPrefixLocal') !== '') {
            trigger_error(
                '%Attr.IDPrefixLocal cannot be used unless ' .
                '%Attr.IDPrefix is set',
                E_USER_WARNING
            );
        }

        if (!$this->selector) {
            $id_accumulator =& $context->get('IDAccumulator');
            if (isset($id_accumulator->ids[$id])) {
                return false;
            }
        }

        // we purposely avoid using regex, hopefully this is faster

        if ($config->get('Attr.ID.HTML5') === true) {
            if (preg_match('/[\t\n\x0b\x0c ]/', $id)) {
                return false;
            }
        } else {
            if (ctype_alpha($id)) {
                // OK
            } else {
                if (!ctype_alpha(@$id[0])) {
                    return false;
                }
                // primitive style of regexps, I suppose
                $trim = trim(
                    $id,
                    'A..Za..z0..9:-._'
                );
                if ($trim !== '') {
                    return false;
                }
            }
        }

        $regexp = $config->get('Attr.IDBlacklistRegexp');
        if ($regexp && preg_match($regexp, $id)) {
            return false;
        }

        if (!$this->selector) {
            $id_accumulator->add($id);
        }

        // if no change was made to the ID, return the result
        // else, return the new id if stripping whitespace made it
        //     valid, or return false.
        return $id;
    }
}

// vim: et sw=4 sts=4
Best Practice

Best Practices

To ensure a smooth integration process and optimal performance, follow these best practices:

  1. Use secure HTTPS connections for all API requests.
  2. Implement robust error handling to handle potential issues gracefully.
  3. Regularly update your integration to stay current with any API changes or enhancements.