code-style

File Naming

```

class-{name}.php # Regular classes.

trait-{name}.php # Traits.

interface-{name}.php # Interfaces.

```

Namespace Pattern

```php

namespace Activitypub;

namespace Activitypub\Transformer;

namespace Activitypub\Collection;

namespace Activitypub\Handler;

namespace Activitypub\Activity;

namespace Activitypub\Rest;

```

Text Domain

Always use 'activitypub' for translations:

```php

\__( 'Text', 'activitypub' );

\_e( 'Text', 'activitypub' );

```

WordPress Global Functions

When in a namespace, always escape WordPress functions with backslash: \get_option(), \add_action(), etc.

See [PHP Coding Standards](../../../docs/php-coding-standards.md) for complete WordPress coding standards.

See [PHP Class Structure](../../../docs/php-class-structure.md) for detailed directory organization.

```

includes/

├── class-*.php # Core classes.

├── activity/ # Activity type classes.

├── collection/ # Collection classes.

├── handler/ # Activity handlers.

├── rest/ # REST API endpoints.

├── transformer/ # Content transformers.

└── wp-admin/ # Admin functionality.

integration/ # Third-party integrations (root level).

```

Transformers

Convert WordPress content into ActivityPub objects.

When to use: Converting posts, comments, users, or custom content types into ActivityPub format.

Base class: includes/transformer/class-base.php

Pattern:

```php

namespace Activitypub\Transformer;

class Custom extends Base {

/**

* Transform object to ActivityPub format.

*

* @return array The ActivityPub representation.

*/

public function transform() {

$object = parent::transform();

// Custom transformation logic.

return $object;

}

}

```

Examples:

• includes/transformer/class-post.php - Post transformation.
• includes/transformer/class-comment.php - Comment transformation.
• includes/transformer/class-event.php - Event-specific transformation.

Handlers

Process incoming ActivityPub activities from remote servers.

When to use: Processing incoming Follow, Like, Create, Delete, Update, etc. activities.

Pattern: Each handler processes one activity type from the inbox.

Examples:

• includes/handler/class-follow.php - Process Follow activities.
• includes/handler/class-create.php - Process Create activities.
• includes/handler/class-delete.php - Process Delete activities.
• includes/handler/class-like.php - Process Like activities.

Collections

Implement ActivityPub collections (Followers, Following, etc.).

When to use: Exposing lists of actors, activities, or objects via ActivityPub.

Examples:

• includes/collection/class-followers.php - Followers collection.
• includes/collection/class-following.php - Following collection.

REST API Controllers

Expose ActivityPub endpoints.

Namespace: ACTIVITYPUB_REST_NAMESPACE

Examples:

• includes/rest/class-actors-controller.php - Actor endpoint.
• includes/rest/class-inbox-controller.php - Inbox endpoint.
• includes/rest/class-outbox-controller.php - Outbox endpoint.
• includes/rest/class-followers-controller.php - Followers collection endpoint.

```php

// Get remote actor metadata.

$metadata = get_remote_metadata_by_actor( $actor_url );

// Convert ActivityPub object to URI string.

$uri = object_to_uri( $object );

// Enrich content with callbacks.

$content = enrich_content_data( $content, $pattern, $callback );

// Resolve WebFinger handle to actor URL.

$resource = Webfinger::resolve( $handle );

// Get user's ActivityPub actor URL.

$actor_url = get_author_posts_url( $user_id );

// Check if a post type is enabled for ActivityPub.

$enabled = \is_post_type_enabled( $post_type );

```

Core Classes:

• includes/class-activitypub.php - Main plugin initialization.
• includes/class-dispatcher.php - Activity dispatching to followers.
• includes/class-scheduler.php - WP-Cron integration for async tasks.
• includes/class-signature.php - HTTP Signatures for federation.

Activity Types:

• includes/activity/class-activity.php - Base activity class.
• includes/activity/class-follow.php - Follow activity.
• includes/activity/class-undo.php - Undo activity.

Integrations (see [Integration Patterns](../integrations/SKILL.md)):

• integration/class-woocommerce.php - WooCommerce integration.
• integration/class-buddypress.php - BuddyPress integration.
• integration/class-jetpack.php - Jetpack integration.

Static Initialization

```php

class Feature {

/**

* Initialize the class.

*/

public static function init() {

\add_action( 'init', array( self::class, 'register' ) );

\add_filter( 'activitypub_activity_object', array( self::class, 'filter' ) );

}

}

```

Singleton Pattern

```php

class Manager {

private static $instance = null;

public static function get_instance() {

if ( null === self::$instance ) {

self::$instance = new self();

}

return self::$instance;

}

private function __construct() {

$this->init();

}

}

```

Actions:

```php

\do_action( 'activitypub_before_send_activity', $activity );

\do_action( 'activitypub_after_send_activity', $activity, $response );

\do_action( 'activitypub_inbox_received', $activity );

```

Filters:

```php

$activity = \apply_filters( 'activitypub_activity_object', $activity, $post );

$content = \apply_filters( 'activitypub_the_content', $content, $post );

$actor = \apply_filters( 'activitypub_actor_data', $actor, $user_id );

```