index.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/>.

/**
 * Admin tool "APCu management" - Main page
 *
 * @package    tool_apcu
 * @copyright  2020 Alexander Bias, Ulm University <alexander.bias@uni-ulm.de>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

require(__DIR__ . '/../../../config.php');
require_once($CFG->libdir.'/adminlib.php');
require_once($CFG->dirroot.'/'.$CFG->admin.'/tool/apcu/locallib.php');
global $CFG, $FULLME;

// Set up the plugin's main page as external admin page.
admin_externalpage_setup('tool_apcu');

// Check if the APCu tool exists on disk so that we can require it.
if (tool_apcu_verify_guidrop_file() == true) {
    // Page setup.
    $title = get_string('pluginname', 'tool_apcu');
    $PAGE->set_title($title);
    $PAGE->set_heading($title);

    // Output has to be buffered because we want to modify the APCu GUI HTML code and as the APCu GUI sends some HTTP headers.
    ob_start();

    // Include APCu GUI.
    $toolpath = tool_apcu_get_guidrop_path();
    require_once($toolpath);

    // Get buffered content and finish buffering.
    $output = ob_get_contents();
    ob_end_clean();

    // Take control over libXML error handling as the APCu GUI HTML code is not perfect.
    libxml_use_internal_errors(true);

    // Process APCu GUI HTML code into a DOMDocument object.
    $apcudoc = new DOMDocument();
    $apcudoc->loadHTML($output);

    // Process DOM and extract the body tag.
    $apcubodytag = $apcudoc->getElementsByTagName('body')->item(0);
    $apcuguihtml = $apcudoc->saveHTML($apcubodytag);

    // Process DOM and extract the style tag.
    $apcustyletag = $apcudoc->getElementsByTagName('style')->item(0);
    $apcustylescode = $apcustyletag->nodeValue;

    // Throw away any libXML errors which have been raised.
    libxml_clear_errors();

    // Finish control over libXML error handling.
    libxml_use_internal_errors(false);

    // Remove the HTML comments from the style code as they would interfere with the upcoming prefixing.
    $apcustylescode = str_replace('<!--', '', $apcustylescode);
    $apcustylescode = str_replace('//-->', '', $apcustylescode);

    // Prefix all styles to avoid any conflicts with Moodle styles.
    $cssprefix = '#page-admin-tool-apcu-index #region-main';
    $apcustylescode = tool_apcu_get_prefixed_css($apcustylescode, $cssprefix);

    // Add the APCu GUI styles to the page.
    $CFG->additionalhtmlhead .= '<style>'.$apcustylescode.'</style>';

    // Page setup.
    echo $OUTPUT->header();

    // Output APCu GUI.
    echo $apcuguihtml;

    // Page setup.
    echo $OUTPUT->footer();

    // Otherwise.
} else {
    // Try to download and store APCu management GUI file on-the-fly.
    $guidropsuccessful = tool_apcu_do_guidrop();

    // If the download was successful.
    if ($guidropsuccessful) {
        // Add a notification to the stack.
        core\notification::success(get_string('guidropmissingonthefly', 'tool_apcu'));

        // Redirect to the same page again.
        redirect($FULLME);

        // Otherwise.
    } else {
        // Output message about missing APCu GUI file.
        throw new \moodle_exception('guidropmissing', 'tool_apcu');
    }
}