myCRED: My friends leaderboard

/**
 * BP Friends Leaderboard
 * Creates a leaderboard that shows your and your friends balances
 * sorted by your positions. Will show the friend above and below you,
 * unless you are in the bottom or top.
 * @version 1.0
 */
add_shortcode( 'bp_friends_leaderboard', 'mycred_pro_my_friends_leaderboard' );
function mycred_pro_my_friends_leaderboard( $atts ) {

    if ( ! function_exists( 'mycred' ) && ! function_exists( 'friends_get_friend_user_ids' ) )
        return 'missing required plugins';

    $mycred = mycred();
    $user_id = get_current_user_id();
    $leaderboard = array();

    // Make sure the user is not excluded to start of
    if ( ! $mycred->exclude_user( $user_id ) ) {

        // Get friends
        $friends = friends_get_friend_user_ids( $user_id );

        // If we have friends
        if ( ! empty( $friends ) ) {

            // Add ourselves in
            $leaderboard[ $user_id ] = $mycred->get_users_balance( $user_id );

            // Add friends to the list with their balance
            foreach ( $friends as $friend_id )
                $leaderboard[ $friend_id ] = $mycred->get_users_balance( $friend_id );

        }

        // If we have a leaderbaord
        if ( ! empty( $leaderboard ) ) {

            // Sort the array
            arsort( $leaderboard, SORT_NUMERIC );

            // Now we have all friends and us sorted according to balance
            $keys = array_flip( array_keys( $leaderboard ) );
            $values = array_values( $leaderboard );

            $content = '<ul>';

            // We are in top position
            if ( ! isset( $values[ $keys[ $user_id ] - 1 ] ) ) {

                $content .= '<li>Me: ' . $values[ $keys[ $user_id ] ] . '</li>';

                if ( isset( $values[ $keys[ $user_id ] + 1 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] + 1 ) . ': ' . $values[ $keys[ $user_id ] + 1 ] . '</li>';

                if ( isset( $values[ $keys[ $user_id ] + 2 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] + 2 ) . ': ' . $values[ $keys[ $user_id ] + 2 ] . '</li>';

            }

            // We are in bottom position
            elseif ( ! isset( $values[ $keys[ $user_id ] + 1 ] ) ) {

                if ( isset( $values[ $keys[ $user_id ] - 2 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] - 2 ) . ': ' . $values[ $keys[ $user_id ] - 2 ] . '</li>';

                if ( isset( $values[ $keys[ $user_id ] - 1 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] - 1 ) . ': ' . $values[ $keys[ $user_id ] - 1 ] . '</li>';

                $content .= '<li>Me: ' . $values[ $keys[ $user_id ] ] . '</li>';

            }

            // We are surrounded
            else {

                if ( isset( $values[ $keys[ $user_id ] - 1 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] - 1 ) . ': ' . $values[ $keys[ $user_id ] - 1 ] . '</li>';

                $content .= '<li>Me: ' . $values[ $keys[ $user_id ] ] . '</li>';

                if ( isset( $values[ $keys[ $user_id ] + 1 ] ) )
                    $content .= '<li>' . bp_core_get_username( $keys[ $user_id ] + 1 ) . ': ' . $values[ $keys[ $user_id ] + 1 ] . '</li>';

            }

            $content .= '</ul>';
            return $content;

        }

    }

    return 'you have no friends';

}