BBP_Shortcodes::display_topic( array $attr, string $content = '' )

	public function display_topic( $attr, $content = '' ) {

		// Sanity check required info
		if ( !empty( $content ) || ( empty( $attr['id'] ) || !is_numeric( $attr['id'] ) ) )
			return $content;

		// Unset globals
		$this->unset_globals();

		// Set passed attribute to $forum_id for clarity
		$topic_id = bbpress()->current_topic_id = $attr['id'];
		$forum_id = bbp_get_topic_forum_id( $topic_id );

		// Bail if ID passed is not a topic
		if ( !bbp_is_topic( $topic_id ) )
			return $content;

		// Reset the queries if not in theme compat
		if ( !bbp_is_theme_compat_active() ) {

			$bbp = bbpress();

			// Reset necessary forum_query attributes for topics loop to function
			$bbp->forum_query->query_vars['post_type'] = bbp_get_forum_post_type();
			$bbp->forum_query->in_the_loop             = true;
			$bbp->forum_query->post                    = get_post( $forum_id );

			// Reset necessary topic_query attributes for topics loop to function
			$bbp->topic_query->query_vars['post_type'] = bbp_get_topic_post_type();
			$bbp->topic_query->in_the_loop             = true;
			$bbp->topic_query->post                    = get_post( $topic_id );
		}

		// Start output buffer
		$this->start( 'bbp_single_topic' );

		// Check forum caps
		if ( bbp_user_can_view_forum( array( 'forum_id' => $forum_id ) ) ) {
			bbp_get_template_part( 'content', 'single-topic' );

		// Forum is private and user does not have caps
		} elseif ( bbp_is_forum_private( $forum_id, false ) ) {
			bbp_get_template_part( 'feedback', 'no-access'    );
		}

		// Return contents of output buffer
		return $this->end();
	}