From 87de87b2a587ba5eed65b047a85f7d9579c47e32 Mon Sep 17 00:00:00 2001
From: Matt Wiebe <wiebe@automattic.com>
Date: Mon, 12 Jun 2023 11:38:15 -0500
Subject: [PATCH] Followers: use custom post types and postmeta to store

---
 includes/collection/class-followers.php | 185 ++++++++++--------------
 includes/model/class-follower.php       | 126 +++++++++-------
 2 files changed, 154 insertions(+), 157 deletions(-)

diff --git a/includes/collection/class-followers.php b/includes/collection/class-followers.php
index 142a9a1..7217666 100644
--- a/includes/collection/class-followers.php
+++ b/includes/collection/class-followers.php
@@ -15,10 +15,11 @@ use function Activitypub\get_remote_metadata_by_actor;
 /**
  * ActivityPub Followers Collection
  *
+ * @author Matt Wiebe
  * @author Matthias Pfefferle
  */
 class Followers {
-	const TAXONOMY = 'activitypub-followers';
+	const POST_TYPE = 'activitypub_followers';
 	const CACHE_KEY_INBOXES = 'follower_inboxes_%s';
 
 	/**
@@ -27,8 +28,8 @@ class Followers {
 	 * @return void
 	 */
 	public static function init() {
-		// register "followers" taxonomy
-		self::register_taxonomy();
+		// register "followers" post_type
+		self::register_post_type();
 
 		\add_action( 'activitypub_inbox_follow', array( self::class, 'handle_follow_request' ), 10, 2 );
 		\add_action( 'activitypub_inbox_undo', array( self::class, 'handle_undo_request' ), 10, 2 );
@@ -41,31 +42,26 @@ class Followers {
 	 *
 	 * @return void
 	 */
-	public static function register_taxonomy() {
-		$args = array(
-			'labels'            => array(
-				'name'          => _x( 'Followers', 'taxonomy general name', 'activitypub' ),
-				'singular_name' => _x( 'Followers', 'taxonomy singular name', 'activitypub' ),
-				'menu_name'     => __( 'Followers', 'activitypub' ),
-			),
-			'hierarchical'      => false,
-			'show_ui'           => false,
-			'show_in_menu'      => false,
-			'show_in_nav_menus' => false,
-			'show_admin_column' => false,
-			'query_var'         => false,
-			'rewrite'           => false,
-			'public'            => false,
-			'capabilities'      => array(
-				'edit_terms' => null,
-			),
+	private static function register_post_type() {
+		register_post_type(
+			self::POST_TYPE,
+			array(
+				'labels'           => array(
+					'name'          => _x( 'Followers', 'post_type plural name', 'activitypub' ),
+					'singular_name' => _x( 'Follower', 'post_type single name', 'activitypub' ),
+				),
+				'public'           => false,
+				'hierarchical'     => false,
+				'rewrite'          => false,
+				'query_var'        => false,
+				'delete_with_user' => false,
+				'can_export'       => true,
+				'supports'         => array(),
+			)
 		);
 
-		register_taxonomy( self::TAXONOMY, 'user', $args );
-		register_taxonomy_for_object_type( self::TAXONOMY, 'user' );
-
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'name',
 			array(
 				'type'              => 'string',
@@ -76,8 +72,8 @@ class Followers {
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'username',
 			array(
 				'type'              => 'string',
@@ -88,56 +84,48 @@ class Followers {
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'avatar',
 			array(
 				'type'              => 'string',
 				'single'            => true,
-				'sanitize_callback' => function( $value ) {
-					if ( filter_var( $value, FILTER_VALIDATE_URL ) === false ) {
-						return '';
-					}
-
-					return esc_url_raw( $value );
-				},
+				'sanitize_callback' => array( self::class, 'sanitize_url' ),
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
+			'url',
+			array(
+				'type'              => 'string',
+				'single'            => false,
+				'sanitize_callback' => array( self::class, 'sanitize_url' ),
+			)
+		);
+
+		register_post_meta(
+			self::POST_TYPE,
 			'inbox',
 			array(
 				'type'              => 'string',
 				'single'            => true,
-				'sanitize_callback' => function( $value ) {
-					if ( filter_var( $value, FILTER_VALIDATE_URL ) === false ) {
-						throw new Exception( '"inbox" has to be a valid URL' );
-					}
-
-					return esc_url_raw( $value );
-				},
+				'sanitize_callback' => array( self::class, 'sanitize_url' ),
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'shared_inbox',
 			array(
 				'type'              => 'string',
 				'single'            => true,
-				'sanitize_callback' => function( $value ) {
-					if ( filter_var( $value, FILTER_VALIDATE_URL ) === false ) {
-						return null;
-					}
-
-					return esc_url_raw( $value );
-				},
+				'sanitize_callback' => array( self::class, 'sanitize_url' ),
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'updated_at',
 			array(
 				'type'              => 'string',
@@ -152,8 +140,8 @@ class Followers {
 			)
 		);
 
-		register_term_meta(
-			self::TAXONOMY,
+		register_post_meta(
+			self::POST_TYPE,
 			'errors',
 			array(
 				'type'              => 'string',
@@ -168,7 +156,15 @@ class Followers {
 			)
 		);
 
-		do_action( 'activitypub_after_register_taxonomy' );
+		do_action( 'activitypub_after_register_post_type' );
+	}
+
+	public static function sanitize_url( $value ) {
+		if ( filter_var( $value, FILTER_VALIDATE_URL ) === false ) {
+			return null;
+		}
+
+		return esc_url_raw( $value );
 	}
 
 	/**
@@ -217,12 +213,10 @@ class Followers {
 			return $meta;
 		}
 
-		$follower = new Follower( $actor );
+		$follower = new Follower( $actor, $user_id );
 		$follower->from_meta( $meta );
 		$follower->upsert();
 
-		$result = wp_set_object_terms( $user_id, $follower->get_actor(), self::TAXONOMY, true );
-
 		if ( is_wp_error( $result ) ) {
 			return $result;
 		} else {
@@ -241,7 +235,7 @@ class Followers {
 	 */
 	public static function remove_follower( $user_id, $actor ) {
 		wp_cache_delete( sprintf( self::CACHE_KEY_INBOXES, $user_id ), 'activitypub' );
-		return wp_remove_object_terms( $user_id, $actor, self::TAXONOMY );
+		return wp_remove_object_terms( $user_id, $actor, self::POST_TYPE );
 	}
 
 	/**
@@ -253,24 +247,8 @@ class Followers {
 	 * @return \Activitypub\Model\Follower The Follower object
 	 */
 	public static function get_follower( $user_id, $actor ) {
-		$terms = new WP_Term_Query(
-			array(
-				'name'       => $actor,
-				'taxonomy'   => self::TAXONOMY,
-				'hide_empty' => false,
-				'object_ids' => $user_id,
-				'number'     => 1,
-			)
-		);
-
-		$term = $terms->get_terms();
-
-		if ( is_array( $term ) && ! empty( $term ) ) {
-			$term = reset( $term );
-			return new Follower( $term->name );
-		}
-
-		return null;
+		$posts = self::get_followers( $user_id, null, null, array( 'name' => $actor ) );
+		return is_empty( $posts ) ? null : $posts[0];
 	}
 
 	/**
@@ -321,21 +299,20 @@ class Followers {
 	 */
 	public static function get_followers( $user_id, $number = null, $offset = null, $args = array() ) {
 		$defaults = array(
-			'taxonomy'   => self::TAXONOMY,
-			'hide_empty' => false,
-			'object_ids' => $user_id,
+			'post_type'  => self::POST_TYPE,
+			'author'     => $user_id,
 			'number'     => $number,
 			'offset'     => $offset,
 			'orderby'    => 'id',
-			'order'      => 'ASC',
+			'order'      => 'DESC',
 		);
 
 		$args  = wp_parse_args( $args, $defaults );
-		$terms = new WP_Term_Query( $args );
+		$query = new WP_Query( $args );
 		$items = array();
 
-		foreach ( $terms->get_terms() as $follower ) {
-			$items[] = new Follower( $follower->name ); // phpcs:ignore
+		foreach ( $query->get_posts() as $post ) {
+			$items[] = new Follower( $post ); // phpcs:ignore
 		}
 
 		return $items;
@@ -348,16 +325,12 @@ class Followers {
 	 *
 	 * @return array The Term list of Followers.
 	 */
-	public static function get_all_followers( $args = array() ) {
-		$defaults = array(
-			'taxonomy'   => self::TAXONOMY,
-			'hide_empty' => false,
+	public static function get_all_followers( $user_id = null ) {
+		$args = array(
+			'author' => null,
+			'nopaging' => true,
 		);
-
-		$args  = wp_parse_args( $args, $defaults );
-		$terms = new WP_Term_Query( $args );
-
-		return $terms->get_terms();
+		return self::get_followers( $user_id, null, null, $args );
 	}
 
 	/**
@@ -367,8 +340,10 @@ class Followers {
 	 *
 	 * @return int The number of Followers
 	 */
-	public static function count_followers( $user_id ) {
-		return count( self::get_followers( $user_id ) );
+	public static function count_followers( $user_id = null ) {
+		// todo: rethink this. Don't we already get a total_posts count out of WP_Query?
+		// in the absence of that: caching.
+		return count( self::get_all_followers( $user_id ) );
 	}
 
 	/**
@@ -389,7 +364,7 @@ class Followers {
 		// get all Followers of a ID of the WordPress User
 		$terms = new WP_Term_Query(
 			array(
-				'taxonomy'   => self::TAXONOMY,
+				'taxonomy'   => self::POST_TYPE,
 				'hide_empty' => false,
 				'object_ids' => $user_id,
 				'fields'     => 'ids',
@@ -436,7 +411,7 @@ class Followers {
 	 */
 	public static function get_outdated_followers( $number = 50, $older_than = 604800 ) {
 		$args = array(
-			'taxonomy'   => self::TAXONOMY,
+			'taxonomy'   => self::POST_TYPE,
 			'number'     => $number,
 			'meta_key'   => 'updated_at',
 			'orderby'    => 'meta_value_num',
@@ -455,7 +430,7 @@ class Followers {
 		$items = array();
 
 		foreach ( $terms->get_terms() as $follower ) {
-			$items[] = new Follower( $follower->name ); // phpcs:ignore
+			$items[] = new Follower( $follower ); // phpcs:ignore
 		}
 
 		return $items;
@@ -471,7 +446,7 @@ class Followers {
 	 */
 	public static function get_faulty_followers( $number = 10 ) {
 		$args = array(
-			'taxonomy'   => self::TAXONOMY,
+			'taxonomy'   => self::POST_TYPE,
 			'number'     => $number,
 			'meta_query' => array(
 				array(
@@ -485,7 +460,7 @@ class Followers {
 		$items = array();
 
 		foreach ( $terms->get_terms() as $follower ) {
-			$items[] = new Follower( $follower->name ); // phpcs:ignore
+			$items[] = new Follower( $follower ); // phpcs:ignore
 		}
 
 		return $items;
diff --git a/includes/model/class-follower.php b/includes/model/class-follower.php
index a663270..43a5934 100644
--- a/includes/model/class-follower.php
+++ b/includes/model/class-follower.php
@@ -9,6 +9,7 @@ use Activitypub\Collection\Followers;
  * This Object represents a single Follower.
  * There is no direct reference to a WordPress User here.
  *
+ * @author Matt Wiebe
  * @author Matthias Pfefferle
  *
  * @see https://www.w3.org/TR/activitypub/#follow-activity-inbox
@@ -61,6 +62,11 @@ class Follower {
 	 */
 	private $avatar;
 
+	/**
+	 * The URL to the Follower
+	 */
+	private $url;
+
 	/**
 	 * The URL to the Followers Inbox
 	 *
@@ -108,6 +114,12 @@ class Follower {
 	 */
 	private $errors;
 
+	/**
+	 * The WordPress User ID, or 0 for whole site.
+	 * @var int
+	 */
+	private $user_id;
+
 	/**
 	 * Maps the meta fields to the local db fields
 	 *
@@ -117,22 +129,29 @@ class Follower {
 		'name'              => 'name',
 		'preferredUsername' => 'username',
 		'inbox'             => 'inbox',
+		'url'               => 'url',
 	);
 
 	/**
 	 * Constructor
 	 *
-	 * @param WP_Post $post
+	 * @param string|WP_Post $actor The Actor-URL or WP_Post Object.
+	 * @param int            $user_id The WordPress User ID. 0 Represents the whole site.
 	 */
-	public function __construct( $actor ) {
-		$this->actor = $actor;
+	public function __construct( $actor, $user_id = 0 ) {
+		$this->user_id = $user_id;
+		if ( is_a( $actor, 'WP_Post' ) ) {
+			$post = $actor;
+			$this->actor = $post->post_name;
+			$this->user_id = $post->post_author;
+		} else {
+			$this->actor = $actor;
+			$post = Followers::get_follower( $user_id, $actor );
+		}
 
-		$term = get_term_by( 'name', $actor, Followers::TAXONOMY );
-
-		if ( $term ) {
-			$this->id = $term->term_id;
-			$this->slug = $term->slug;
-			$this->meta = json_decode( $term->meta );
+		if ( $post ) {
+			$this->id = $term->post_id;
+			$this->slug = $term->post_name;
 		}
 	}
 
@@ -205,25 +224,38 @@ class Follower {
 	 * @return mixed The attribute value.
 	 */
 	public function get( $attribute ) {
-		if ( $this->$attribute ) {
+		if ( ! is_null( $this->$attribute ) ) {
 			return $this->$attribute;
 		}
-
-		$attribute = get_term_meta( $this->id, $attribute, true );
-		if ( $attribute ) {
-			$this->$attribute = $attribute;
-			return $attribute;
+		$attribute_value = get_post_meta( $this->id, $attribute, true );
+		if ( $attribute_value ) {
+			$this->$attribute = $attribute_value;
+			return $attribute_value;
 		}
 
-		$attribute = $this->get_meta_by( $attribute );
-		if ( $attribute ) {
-			$this->$attribute = $attribute;
-			return $attribute;
+		$attribute_value = $this->get_meta_by( $attribute );
+		if ( $attribute_value ) {
+			$this->$attribute = $attribute_value;
+			return $attribute_value;
 		}
 
 		return null;
 	}
 
+	/**
+	 * Get a URL for the follower. Creates one out of the actor if no URL was set.
+	 */
+	public function get_url() {
+		if ( $this->get( 'url' ) ) {
+			return $this->get( 'url' );
+		}
+		$actor = $this->get_actor();
+		// normalize
+		$actor = ltrim( $actor, '@' );
+		$parts = explode( '@', $actor );
+		return sprintf( 'https://%s/@%s', $parts[1], $parts[0] );
+	}
+
 	/**
 	 * Set new Error
 	 *
@@ -246,7 +278,7 @@ class Follower {
 			return $this->errors;
 		}
 
-		$this->errors = get_term_meta( $this->id, 'errors' );
+		$this->errors = get_post_meta( $this->id, 'errors' );
 		return $this->errors;
 	}
 
@@ -298,7 +330,9 @@ class Follower {
 	 */
 	public function get_meta_by( $attribute ) {
 		$meta = $this->get_meta();
-
+		if ( ! is_array( $meta ) ) {
+			return null;
+		}
 		// try mapped data (see $this->map_meta)
 		foreach ( $this->map_meta as $remote => $local ) {
 			if ( $attribute === $local && isset( $meta[ $remote ] ) ) {
@@ -306,11 +340,6 @@ class Follower {
 			}
 		}
 
-		// try ActivityPub attribtes
-		if ( ! empty( $this->map_meta[ $attribute ] ) ) {
-			return $this->map_meta[ $attribute ];
-		}
-
 		return null;
 	}
 
@@ -333,16 +362,8 @@ class Follower {
 	 * @return void
 	 */
 	public function update() {
-		$term = wp_update_term(
-			$this->id,
-			Followers::TAXONOMY,
-			array(
-				'description' => wp_json_encode( $this->get_meta( true ) ),
-			)
-		);
-
 		$this->updated_at = \time();
-		$this->update_term_meta();
+		$this->save( $this->id );
 	}
 
 	/**
@@ -350,19 +371,16 @@ class Follower {
 	 *
 	 * @return void
 	 */
-	public function save() {
-		$term = wp_insert_term(
-			$this->actor,
-			Followers::TAXONOMY,
-			array(
-				'slug'        => sanitize_title( $this->get_actor() ),
-				'description' => wp_json_encode( $this->get_meta() ),
-			)
+	public function save( $post_id = null ) {
+		$args = array(
+			'ID' => $post_id,
+			'post_name' => $this->actor,
+			'post_author' => $this->user_id,
+			'post_type' => Followers::POST_TYPE,
+			'meta_input' => $this->get_post_meta_input(),
 		);
-
-		$this->id = $term['term_id'];
-
-		$this->update_term_meta();
+		$post = wp_insert_post( $args );
+		$this->id = $post->ID;
 	}
 
 	/**
@@ -384,7 +402,7 @@ class Follower {
 	 * @return void
 	 */
 	public function delete() {
-		wp_delete_term( $this->id, Followers::TAXONOMY );
+		wp_delete_post( $this->id );
 	}
 
 	/**
@@ -392,12 +410,14 @@ class Follower {
 	 *
 	 * @return void
 	 */
-	protected function update_term_meta() {
-		$attributes = array( 'inbox', 'shared_inbox', 'avatar', 'updated_at', 'name', 'username' );
+	protected function get_post_meta_input() {
+		$attributes = array( 'inbox', 'shared_inbox', 'avatar', 'updated_at', 'name', 'username', 'url' );
+
+		$meta_input = array();
 
 		foreach ( $attributes as $attribute ) {
 			if ( $this->get( $attribute ) ) {
-				update_term_meta( $this->id, $attribute, $this->get( $attribute ) );
+				$meta_input[ $attribute ] = $this->get( $attribute );
 			}
 		}
 
@@ -410,7 +430,9 @@ class Follower {
 				$error = __( 'Unknown Error or misconfigured Error-Message', 'activitypub' );
 			}
 
-			add_term_meta( $this->id, 'errors', $error );
+			$meta_input['errors'] = array( $error );
 		}
+
+		return $meta_input;
 	}
 }