wordpress-activitypub/includes/class-activitypub.php

<?php

class Activitypub {
	public static function render_json_template( $template ) {
		if ( ! is_author() && ! is_singular() ) {
			return $template;
		}

		if ( is_author() ) {
			$json_template = dirname( __FILE__ ) . '/../templates/json-author.php';
		} elseif ( is_singular() ) {
			$json_template = dirname( __FILE__ ) . '/../templates/json-post.php';
		}

		global $wp_query;

		if ( isset( $wp_query->query_vars['activitypub'] ) ) {
			return $json_template;
		}

		if ( ! isset( $_SERVER['HTTP_ACCEPT'] ) ) {
			return $template;
		}

		// interpret accept header
		$pos = stripos( $_SERVER['HTTP_ACCEPT'], ';' );
		if ( $pos ) {
			$accept_header = substr( $_SERVER['HTTP_ACCEPT'], 0, $pos );
		} else {
			$accept_header = $_SERVER['HTTP_ACCEPT'];
		}
		// accept header as an array
		$accept = explode( ',', trim( $accept_header ) );

		if (
			! in_array( 'application/activity+json', $accept, true ) &&
			! in_array( 'application/ld+json', $accept, true ) &&
			! in_array( 'application/json', $accept, true )
		) {
			return $template;
		}

		return $json_template;
	}

	/**
	 * Add WebFinger discovery links
	 *
	 * @param array   $array    the jrd array
	 * @param string  $resource the WebFinger resource
	 * @param WP_User $user     the WordPress user
	 */
	public static function add_webfinger_discovery( $array, $resource, $user ) {
		$array['links'][] = array(
			'rel'  => 'self',
			'type' => 'application/activity+json',
			'href' => get_author_posts_url( $user->ID ),
		);

		return $array;
	}

	/**
	 * Add the 'photos' query variable so WordPress
	 * won't mangle it.
	 */
	public static function add_query_vars( $vars ) {
		$vars[] = 'activitypub';

		return $vars;
	}

	/**
	 * Add our rewrite endpoint to permalinks and pages.
	 */
	public static function add_rewrite_endpoint() {
		add_rewrite_endpoint( 'activitypub', EP_AUTHORS | EP_PERMALINK | EP_PAGES );
	}
}