friendica-addons/opmlexport/opmlexport.php

<?php
/**
 * Name: OPML Export
 * Description: Export user's RSS/Atom contacts as OPML
 * Version: 1.0
 * Author: Fabio Comuni <https://social.gl-como.it/profile/fabrixxm>
 * License: 3-clause BSD license
 */

use Friendica\DI;
use Friendica\App;
use Friendica\Core\Hook;
use Friendica\Core\Logger;
use Friendica\Network\HTTPException;
use Friendica\Database\DBA;
use Friendica\Core\Renderer;
use Friendica\Core\Protocol;
use Friendica\Model\Contact;

function opmlexport_install()
{
    Hook::register('addon_settings',        __FILE__, 'opmlexport_addon_settings');
    Hook::register('addon_settings_post',   __FILE__, 'opmlexport_addon_settings_post');
    Logger::log('installed opmlexport Addon');
}


    $stmt = DBA::p("SELECT *
            FROM `contact`
            WHERE `uid` = ?
                AND `self` = 0
                AND NOT `deleted`
                AND NOT `archive` AND NOT `blocked` AND NOT `pending`
                AND network = ?
            ORDER BY `name` ASC",
            [local_user(), "feed"]
    );

function opmlexport(App $a)
{

    $xml = new \DOMDocument( '1.0', 'utf-8' );
    $opml = $xml->createElement('opml');
    $head = $xml->createElement('head');
    $body = $xml->createElement('body');
    $outline = $xml->createElement('outline');
    $outline->setAttribute('title', $a->user['username'] . '\'s RSS/Atom contacts');
    $outline->setAttribute('text', $a->user['username'] . '\'s RSS/Atom contacts');

    while ($c = DBA::fetch($stmt)) {
        $entry = $xml->createElement('outline');
        $entry->setAttribute('title',  $c['name']);
        $entry->setAttribute('text',   $c['name']);
        $entry->setAttribute('xmlUrl', $c['url']);
        $outline->appendChild($entry);
    }
    DBA::close($stmt);

    $body->appendChild($outline);
    $opml->appendChild($head);
    $opml->appendChild($body);
    $xml->appendChild($opml);
    header('Content-Type: text/x-opml');
    header('Content-Disposition: attachment; filename=feeds.opml');
    $xml->formatOutput = true;
    echo $xml->saveXML();
    die();
}


function opmlexport_addon_settings(App $a, &$s)
{
    if (!local_user()) {
        return;
    }

    $t = Renderer::getMarkupTemplate('settings.tpl', 'addon/opmlexport/');
    $s .= Renderer::replaceMacros($t, [
        '$title'   => DI::l10n()->t('OPML Export'),
        '$submit'  => DI::l10n()->t('Export RSS/Atom contacts'),
    ]);
}


function opmlexport_addon_settings_post(App $a, &$b)
{
    if (!local_user() || empty($_POST['opmlexport-submit'])) {
        return;
    }
    opmlexport($a);
}