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;

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");
}


function opmlexport(App $a) {
    $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"]
    );


    $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"]);
        // $entry->setAttribute("htmlUrl", $c[""]);
        $outline->appendChild($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);
}