proxy_pluginfile.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Pluginfile proxy script.
 *
 * @package   mod_hvp
 * @author    Kevin Pham <kevinpham@catalyst-au.net>
 * @copyright Catalyst IT, 2021
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

require_once(dirname(__FILE__) . '/../../config.php');
require_once($CFG->libdir . '/filelib.php');
\core\session\manager::write_close();

$relativepath = get_file_argument();

if (empty($relativepath)) {
    exit();
}

// This should target the custom content types. We also filter out the
// Content-Length Header in this case to avoid truncation.
$jstobereplaced = stripos($relativepath, 'cachedassets') !== false && stripos($relativepath, '.js') !== false;
$url = new moodle_url('/pluginfile.php/'.ltrim($relativepath, '/'));
if (!$jstobereplaced) {
    header("Location: $url");
    die; // This will never be reached!
} else {
    header('Content-Type: application/javascript');
}

$curl = new curl();

// Add user cookies to the request, to ensure they are processed properly.
$cookiestr = [];
foreach ($_COOKIE as $key => $value) {
    $cookiestr[] = $key.'='.$value;
}
$cookiestr = implode('; ', $cookiestr) . ';';
$curl->setHeader('Cookie: '.$cookiestr);

$curl->setopt([
    'CURLOPT_WRITEFUNCTION'  => function ($curl, $body) use ($jstobereplaced, $relativepath) {
        // Even if we modify the body, we need to return the original length.
        $originalbodylength = strlen($body);

        // Remove the transitionend event which occurs in the referenced
        // link, to prevent card focusing on page load, as this might be
        // included as embedded content, and a page scroll/focus does not
        // make sense.
        // https://github.com/h5p/h5p-dialogcards/blob/7a7580aad3424c60f45cb65eac52ff14bc83b540/src/scripts/h5p-dialogcards-card.js#L482-L484.
        $body = str_replace('.one("transitionend",', '.off("_removed_",', $body);
        echo $body;

        return $originalbodylength;
    },
]);

// The proxy will pass content back from pluginfile.php
$url = new moodle_url('/pluginfile.php/'.ltrim($relativepath, '/'));
$curl->get($url->out());