bbp_get_user_profile_url( int $user_id, string $user_nicename = '' )

	function bbp_get_user_profile_url( $user_id = 0, $user_nicename = '' ) {
		global $wp_rewrite;

		// Use displayed user ID if there is one, and one isn't requested
		$user_id = bbp_get_user_id( $user_id );
		if ( empty( $user_id ) )
			return false;

		// Allow early overriding of the profile URL to cut down on processing
		$early_profile_url = apply_filters( 'bbp_pre_get_user_profile_url', (int) $user_id );
		if ( is_string( $early_profile_url ) )
			return $early_profile_url;

		// Pretty permalinks
		if ( $wp_rewrite->using_permalinks() ) {
			$url = $wp_rewrite->root . bbp_get_user_slug() . '/%' . bbp_get_user_rewrite_id() . '%';

			// Get username if not passed
			if ( empty( $user_nicename ) ) {
				$user_nicename = bbp_get_user_nicename( $user_id );
			}

			$url = str_replace( '%' . bbp_get_user_rewrite_id() . '%', $user_nicename, $url );
			$url = home_url( user_trailingslashit( $url ) );

		// Unpretty permalinks
		} else {
			$url = add_query_arg( array( bbp_get_user_rewrite_id() => $user_id ), home_url( '/' ) );
		}

		return apply_filters( 'bbp_get_user_profile_url', $url, $user_id, $user_nicename );
	}