<?php
/**
* This is the class for integrating ActivityPub into the Friends Plugin.
*
* @since 0.14
*
* @package ActivityPub
* @author Alex Kirk
*/
namespace Activitypub;
class Friends_Feed_Parser_ActivityPub extends \Friends\Feed_Parser {
const SLUG = 'activitypub';
const NAME = 'ActivityPub';
const URL = 'https://www.w3.org/TR/activitypub/';
private $friends_feed;
/**
* Constructor.
*
* @param \Friends\Feed $friends_feed The friends feed
*/
public function __construct( \Friends\Feed $friends_feed ) {
$this->friends_feed = $friends_feed;
\add_action( 'activitypub_inbox', array( $this, 'handle_received_activity' ), 10, 3 );
\add_action( 'friends_user_feed_activated', array( $this, 'queue_follow_user' ), 10 );
\add_action( 'friends_user_feed_deactivated', array( $this, 'queue_unfollow_user' ), 10 );
\add_action( 'friends_feed_parser_activitypub_follow', array( $this, 'follow_user' ), 10, 2 );
\add_action( 'friends_feed_parser_activitypub_unfollow', array( $this, 'unfollow_user' ), 10, 2 );
\add_filter( 'friends_rewrite_incoming_url', array( $this, 'friends_rewrite_incoming_url' ), 10, 2 );
}
/**
* Allow logging a message via an action.
* @param string $message The message to log.
* @param array $objects Optional objects as meta data.
* @return void
*/
private function log( $message, $objects = array() ) {
do_action( 'friends_activitypub_log', $message, $objects );
}
/**
* Determines if this is a supported feed and to what degree we feel it's supported.
*
* @param string $url The url.
* @param string $mime_type The mime type.
* @param string $title The title.
* @param string|null $content The content, it can't be assumed that it's always available.
*
* @return int Return 0 if unsupported, a positive value representing the confidence for the feed, use 10 if you're reasonably confident.
*/
public function feed_support_confidence( $url, $mime_type, $title, $content = null ) {
if ( preg_match( '/^@?[^@]+@((?:[a-z0-9-]+\.)+[a-z]+)$/i', $url ) ) {
return 10;
}
return 0;
}
/**
* Format the feed title and autoselect the posts feed.
*
* @param array $feed_details The feed details.
*
* @return array The (potentially) modified feed details.
*/
public function update_feed_details( $feed_details ) {
$meta = \Activitypub\get_remote_metadata_by_actor( $feed_details['url'] );
if ( ! $meta || is_wp_error( $meta ) ) {
return $meta;
}
if ( isset( $meta['name'] ) ) {
$feed_details['title'] = $meta['name'];
} elseif ( isset( $meta['preferredUsername'] ) ) {
$feed_details['title'] = $meta['preferredUsername'];
}
if ( isset( $meta['id'] ) ) {
$feed_details['url'] = $meta['id'];
}
return $feed_details;
}
/**
* Rewrite a Mastodon style URL @username@server to a URL via webfinger.
*
* @param string $url The URL to filter.
* @param string $incoming_url Potentially a mastodon identifier.
*
* @return <type> ( description_of_the_return_value )
*/
public function friends_rewrite_incoming_url( $url, $incoming_url ) {
if ( preg_match( '/^@?[^@]+@((?:[a-z0-9-]+\.)+[a-z]+)$/i', $incoming_url ) ) {
$resolved_url = \Activitypub\Webfinger::resolve( $incoming_url );
if ( ! is_wp_error( $resolved_url ) ) {
return $resolved_url;
}
}
return $url;
}
/**
* Discover the feeds available at the URL specified.
*
* @param string $content The content for the URL is already provided here.
* @param string $url The url to search.
*
* @return array A list of supported feeds at the URL.
*/
public function discover_available_feeds( $content, $url ) {
$discovered_feeds = array();
$meta = \Activitypub\get_remote_metadata_by_actor( $url );
if ( $meta && ! is_wp_error( $meta ) ) {
$discovered_feeds[ $meta['id'] ] = array(
'type' => 'application/activity+json',
'rel' => 'self',
'post-format' => 'status',
'parser' => self::SLUG,
'autoselect' => true,
);
}
return $discovered_feeds;
}
/**
* Fetches a feed and returns the processed items.
*
* @param string $url The url.
*
* @return array An array of feed items.
*/
public function fetch_feed( $url ) {
// There is no feed to fetch, we'll receive items via ActivityPub.
return array();
}
/**
* Handles "Create" requests
*
* @param array $object The activity-object
* @param int $user_id The id of the local blog-user
* @param string $type The type of the activity.
*/
public function handle_received_activity( $object, $user_id, $type ) {
if ( ! in_array(
$type,
array(
// We don't need to handle 'Accept' types since it's handled by the ActivityPub plugin itself.
'create',
'announce',
),
true
) ) {
return false;
}
$actor_url = $object['actor'];
$user_feed = false;
if ( \wp_http_validate_url( $actor_url ) ) {
// Let's check if we follow this actor. If not it might be a different URL representation.
$user_feed = $this->friends_feed->get_user_feed_by_url( $actor_url );
}
if ( is_wp_error( $user_feed ) || ! \wp_http_validate_url( $actor_url ) ) {
$meta = \Activitypub\get_remote_metadata_by_actor( $actor_url );
if ( ! $meta || ! isset( $meta['url'] ) ) {
$this->log( 'Received invalid meta for ' . $actor_url );
return false;
}
$actor_url = $meta['url'];
if ( ! \wp_http_validate_url( $actor_url ) ) {
$this->log( 'Received invalid meta url for ' . $actor_url );
return false;
}
}
$user_feed = $this->friends_feed->get_user_feed_by_url( $actor_url );
if ( ! $user_feed || is_wp_error( $user_feed ) ) {
$this->log( 'We\'re not following ' . $actor_url );
// We're not following this user.
return false;
}
switch ( $type ) {
case 'create':
return $this->handle_incoming_post( $object['object'], $user_feed );
case 'announce':
return $this->handle_incoming_announce( $object['object'], $user_feed, $user_id );
}
return true;
}
/**
* Map the Activity type to a post fomat.
*
* @param string $type The type.
*
* @return string The determined post format.
*/
private function map_type_to_post_format( $type ) {
return 'status';
}
/**
* We received a post for a feed, handle it.
*
* @param array $object The object from ActivityPub.
* @param \Friends\User_Feed $user_feed The user feed.
*/
private function handle_incoming_post( $object, \Friends\User_Feed $user_feed ) {
$permalink = $object['id'];
if ( isset( $object['url'] ) ) {
$permalink = $object['url'];
}
$data = array(
'permalink' => $permalink,
'content' => $object['content'],
'post_format' => $this->map_type_to_post_format( $object['type'] ),
'date' => $object['published'],
);
if ( isset( $object['attributedTo'] ) ) {
$meta = \Activitypub\get_remote_metadata_by_actor( $object['attributedTo'] );
$this->log( 'Attributed to ' . $object['attributedTo'], compact( 'meta' ) );
if ( isset( $meta['name'] ) ) {
$data['author'] = $meta['name'];
} elseif ( isset( $meta['preferredUsername'] ) ) {
$data['author'] = $meta['preferredUsername'];
}
}
if ( ! empty( $object['attachment'] ) ) {
foreach ( $object['attachment'] as $attachment ) {
if ( ! isset( $attachment['type'] ) || ! isset( $attachment['mediaType'] ) ) {
continue;
}
if ( 'Document' !== $attachment['type'] || strpos( $attachment['mediaType'], 'image/' ) !== 0 ) {
continue;
}
$data['content'] .= PHP_EOL;
$data['content'] .= '<!-- wp:image -->';
$data['content'] .= '<p><img src="' . esc_url( $attachment['url'] ) . '" width="' . esc_attr( $attachment['width'] ) . '" height="' . esc_attr( $attachment['height'] ) . '" class="size-full" /></p>';
$data['content'] .= '<!-- /wp:image -->';
}
$meta = \Activitypub\get_remote_metadata_by_actor( $object['attributedTo'] );
$this->log( 'Attributed to ' . $object['attributedTo'], compact( 'meta' ) );
if ( isset( $meta['name'] ) ) {
$data['author'] = $meta['name'];
} elseif ( isset( $meta['preferredUsername'] ) ) {
$data['author'] = $meta['preferredUsername'];
}
}
$this->log(
'Received feed item',
array(
'url' => $permalink,
'data' => $data,
)
);
$item = new \Friends\Feed_Item( $data );
$this->friends_feed->process_incoming_feed_items( array( $item ), $user_feed );
return true;
}
/**
* We received an announced URL (boost) for a feed, handle it.
*
* @param array $url The announced URL.
* @param \Friends\User_Feed $user_feed The user feed.
*/
private function handle_incoming_announce( $url, \Friends\User_Feed $user_feed, $user_id ) {
if ( ! \wp_http_validate_url( $url ) ) {
$this->log( 'Received invalid announce', compact( 'url' ) );
return false;
}
$this->log( 'Received announce for ' . $url );
$response = \Activitypub\safe_remote_get( $url, $user_id );
if ( \is_wp_error( $response ) ) {
return $response;
}
$json = \wp_remote_retrieve_body( $response );
$object = \json_decode( $json, true );
if ( ! $object ) {
$this->log( 'Received invalid json', compact( 'json' ) );
return false;
}
$this->log( 'Received response', compact( 'url', 'object' ) );
return $this->handle_incoming_post( $object, $user_feed );
}
/**
* Prepare to follow the user via a scheduled event.
*
* @param \Friends\User_Feed $user_feed The user feed.
*
* @return bool|WP_Error Whether the event was queued.
*/
public function queue_follow_user( \Friends\User_Feed $user_feed ) {
if ( self::SLUG !== $user_feed->get_parser() ) {
return;
}
$args = array( $user_feed->get_url(), get_current_user_id() );
$unfollow_timestamp = wp_next_scheduled( 'friends_feed_parser_activitypub_unfollow', $args );
if ( $unfollow_timestamp ) {
// If we just unfollowed, we don't want the event to potentially be executed after our follow event.
wp_unschedule_event( $unfollow_timestamp, $args );
}
if ( wp_next_scheduled( 'friends_feed_parser_activitypub_follow', $args ) ) {
return;
}
return \wp_schedule_single_event( \time(), 'friends_feed_parser_activitypub_follow', $args );
}
/**
* Follow a user via ActivityPub at a URL.
*
* @param string $url The url.
* @param int $user_id The current user id.
*/
public function follow_user( $url, $user_id ) {
$meta = \Activitypub\get_remote_metadata_by_actor( $url );
$to = $meta['id'];
$inbox = \Activitypub\get_inbox_by_actor( $to );
$actor = \get_author_posts_url( $user_id );
$activity = new \Activitypub\Model\Activity( 'Follow', \Activitypub\Model\Activity::TYPE_SIMPLE );
$activity->set_to( null );
$activity->set_cc( null );
$activity->set_actor( $actor );
$activity->set_object( $to );
$activity->set_id( $actor . '#follow-' . \preg_replace( '~^https?://~', '', $to ) );
$activity = $activity->to_json();
\Activitypub\safe_remote_post( $inbox, $activity, $user_id );
}
/**
* Prepare to unfollow the user via a scheduled event.
*
* @param \Friends\User_Feed $user_feed The user feed.
*
* @return bool|WP_Error Whether the event was queued.
*/
public function queue_unfollow_user( \Friends\User_Feed $user_feed ) {
if ( self::SLUG !== $user_feed->get_parser() ) {
return false;
}
$args = array( $user_feed->get_url(), get_current_user_id() );
$follow_timestamp = wp_next_scheduled( 'friends_feed_parser_activitypub_follow', $args );
if ( $follow_timestamp ) {
// If we just followed, we don't want the event to potentially be executed after our unfollow event.
wp_unschedule_event( $follow_timestamp, $args );
}
if ( wp_next_scheduled( 'friends_feed_parser_activitypub_unfollow', $args ) ) {
return true;
}
return \wp_schedule_single_event( \time(), 'friends_feed_parser_activitypub_unfollow', $args );
}
/**
* Unfllow a user via ActivityPub at a URL.
*
* @param string $url The url.
* @param int $user_id The current user id.
*/
public function unfollow_user( $url, $user_id ) {
$meta = \Activitypub\get_remote_metadata_by_actor( $url );
$to = $meta['id'];
$inbox = \Activitypub\get_inbox_by_actor( $to );
$actor = \get_author_posts_url( $user_id );
$activity = new \Activitypub\Model\Activity( 'Undo', \Activitypub\Model\Activity::TYPE_SIMPLE );
$activity->set_to( null );
$activity->set_cc( null );
$activity->set_actor( $actor );
$activity->set_object(
array(
'type' => 'Follow',
'actor' => $actor,
'object' => $to,
'id' => $to,
)
);
$activity->set_id( $actor . '#unfollow-' . \preg_replace( '~^https?://~', '', $to ) );
$activity = $activity->to_json();
\Activitypub\safe_remote_post( $inbox, $activity, $user_id );
}
}