mastodon_target.php

function add_mastodon_syndication_target($synd_urls, $user_id)
{
    $masto_target['uid'] = "social_coop";
    $masto_target['name'] = "social.coop";
    $synd_urls[] = $masto_target;

    return $synd_urls;
}

add_filter("micropub_syndicate-to", "add_mastodon_syndication_target", 10, 2);

function syndicate_to_mastodon($ID, $syndicate_to)
{
    $post = get_post($ID);
    $message = $post->post_content;
    foreach ($syndicate_to as $syndication_target_uid) {
        if ($syndication_target_uid === 'social_coop') {
                $instance = get_option( 'autopostToMastodon-instance' );
                $access_token = get_option('autopostToMastodon-token');
                $mode = get_option( 'autopostToMastodon-mode', 'public' );
                $client = new Client($instance, $access_token);
                $toot = $client->postStatus($message, $mode);
        }
    }
}

add_filter("micropub_syndication", "syndicate_to_mastodon", 10, 2);