myCRED: Custom Widget - This weeks leaderboard

<?php
/**
 * Custom myCRED Widget: This weeks leaderboard
 * This widget will show this weeks leaderbaord with the option to set
 * a title, the number of users to include and if it should be visible for
 * non-members.
 *
 * @author Gabriel S Merovingi
 * @version 1.2.2
 */
if ( function_exists( 'mycred_label' ) ) :
    /**
     * Step 1: Register Widget
     * @version 1.0
     */
    add_action( 'widgets_init', 'mycred_register_custom_widgets' );
    function mycred_register_custom_widgets()
    {
        register_widget( 'myCRED_Widget_This_Weeks_Leaderboard' );
    }

    /**
     * Step 2: Construct Widget
     * @version 1.2
     */
    if ( ! class_exists( 'myCRED_Widget_This_Weeks_Leaderboard' ) ) {
        class myCRED_Widget_This_Weeks_Leaderboard extends WP_Widget {

            // Constructor
            public function __construct() {
                $name = mycred_label();
                // Basic details about our widget
                $widget_ops = array(
                    'classname'   => 'widget-mycred-this-weeks-leaderboard',
                    'description' => __( 'Show the leaderboard for a given timeframe.', 'mycred' )
            );
                $this->WP_Widget( 'mycred_widget_this_weeks_leaderboard', __( 'This weeks Leaderboard', 'mycred' ), $widget_ops );
                $this->alt_option_name = 'mycred_widget_this_weeks_leaderboard';
            }

            // Widget Output (what users see)
            public function widget( $args, $instance ) {
                extract( $args, EXTR_SKIP );

                // Check if we want to show this to visitors
                if ( ! $instance['show_visitors'] && ! is_user_logged_in() ) return;

                // Get the leaderboard
                $leaderboard = $this->get_leaderboard( $instance['number'], $widget_id );

                // Load myCRED
                $mycred = mycred_get_settings();

                // Start constructing Widget
                echo $before_widget;

                // Title (if not empty)
                if ( ! empty( $instance['title'] ) ) {
                    echo $before_title;
                    // Allow general tempalte tags in the title
                    echo $mycred->template_tags_general( $instance['title'] );
                    echo $after_title;
                }

                // Construct unorganized list for each row
                echo '<ul class="mycred-this-weeks-leaderboard">';
                foreach ( $leaderboard as $position => $data ) {
                    echo '<li>' . $data->display_name . ' with ' . $mycred->format_creds( $data->total ) . '</li>';
                }
                echo '</ul>';

                echo $after_widget;
            }

            // Widget Settings (when editing / setting up widget)
            public function form( $instance ) {
                $title = isset( $instance['title'] ) ? esc_attr( $instance['title'] ) : __( 'This Weeks Leaderboard', 'mycred' );
                $number = isset( $instance['number'] ) ? abs( $instance['number'] ) : 5;
                $show_visitors = isset( $instance['show_visitors'] ) ? 1 : 0; ?>

<p class="myCRED-widget-field">
    <label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title', 'mycred' ); ?>:</label>
    <input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>" />
</p>
<p class="myCRED-widget-field">
    <label for="<?php echo esc_attr( $this->get_field_id( 'number' ) ); ?>"><?php _e( 'Number of users', 'mycred' ); ?>:</label>
    <input id="<?php echo esc_attr( $this->get_field_id( 'number' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'number' ) ); ?>" type="text" value="<?php echo $number; ?>" size="3" class="align-right" />
</p>
<p class="myCRED-widget-field">
    <input type="checkbox" name="<?php echo esc_attr( $this->get_field_name( 'show_visitors' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'show_visitors' ) ); ?>" value="1"<?php checked( $show_visitors, 1 ); ?> class="checkbox" />
    <label for="<?php echo esc_attr( $this->get_field_id( 'show_visitors' ) ); ?>"><?php _e( 'Visible to non-members', 'mycred' ); ?></label>
</p>
<?php if ( isset( $this->id ) && $this->id !== false ) : ?>
<p class="myCRED-widget-field">
    <input type="checkbox" name="<?php echo esc_attr( $this->get_field_name( 'reset_leaderboard' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'reset_leaderboard' ) ); ?>" value="1" class="checkbox" />
    <label for="<?php echo esc_attr( $this->get_field_id( 'reset_leaderboard' ) ); ?>"><?php _e( 'Reset Leaderboard', 'mycred' ); ?></label>
</p>
<?php
                endif;
            }

            // Save Widget Settings
            public function update( $new_instance, $old_instance ) {
                $instance = $old_instance;
                $instance['number'] = (int) $new_instance['number'];
                $instance['title'] = trim( $new_instance['title'] );
                $instance['show_visitors'] = $new_instance['show_visitors'];

                if ( isset( $new_instance['reset_leaderboard'] ) && $this->id !== false ) {
                    delete_transient( 'mycred_twl_' . $this->id );
                }

                mycred_flush_widget_cache( 'mycred_widget_this_weeks_leaderboard' );
                return $instance;
            }

            // Grabs the leaderboard
            public function get_leaderboard( $number = 5, $widget_id = '' ) {
                // Get transient
                $data = get_transient( 'mycred_twl_' . $widget_id );
                $this_week = date_i18n( 'W' );

                // If a transient is set, check if it is time for an update
                if ( $data !== false ) {
                    reset( $data );
                    $saved_week = key( $data );
                    // Compare the first array key (which holds the week number) to this weeks
                    // If they do not match, it is a new week and we need to make a new query.
                    // Same goes for empty results (new sites)
                    if ( $this_week != $saved_week || empty( $data[ $saved_week ] ) )
                        $data = false;
                    // Else return the results
                    else
                        $data = $data[ $this_week ];
                }

                // If transient does not exist or a new number is set, do a new DB Query
                if ( $data === false || $number != 5 ) {
                    // Start over
                    $data = array();

                    // Load the wpdb class
                    global $wpdb;

                    $mycred = $wpdb->prefix . 'myCRED_log';
                    $SQL = "
SELECT m.user_id, u.display_name, sum( m.creds ) AS total
FROM {$mycred} m
LEFT JOIN {$wpdb->users} u
    ON u.ID = m.user_id
WHERE ( m.time >= %d AND m.time <= %d AND m.creds > 0 )
GROUP BY m.user_id
ORDER BY total DESC LIMIT 0,%d;";

                    // Save results under this week
                    $now = date_i18n( 'U' );
                    $last_week = strtotime( "-1 week" );
                    $data[ $this_week ] = $wpdb->get_results( $wpdb->prepare( $SQL, $last_week, $now, $number ) );
                    // Save results for a week
                    set_transient( 'mycred_twl_' . $widget_id, $data, WEEK_IN_SECONDS );
                    $data = $data[ $this_week ];
                }

                return $data;
            }
        }
    }

endif; ?>