xoogu error

[28-Jul-2015 20:55:49 UTC] PHP Notice:  Undefined variable: woocommerce in /home/igenero1/public_html/dev.igenero.in/shopping/wp-content/themes/Divi/functions.php on line 5002
[28-Jul-2015 20:55:49 UTC] PHP Notice:  Trying to get property of non-object in /home/igenero1/public_html/dev.igenero.in/shopping/wp-content/themes/Divi/functions.php on line 5002
[28-Jul-2015 20:55:49 UTC] PHP Notice:  Trying to get property of non-object in /home/igenero1/public_html/dev.igenero.in/shopping/wp-content/themes/Divi/functions.php on line 5002
[28-Jul-2015 20:55:49 UTC] PHP Fatal error:  ob_start(): Cannot use output buffering in output buffering display handlers in /home/igenero1/public_html/dev.igenero.in/shopping/wp-content/themes/Divi/functions.php on line 5004



the code in function.php file is

<?php
function cart_notice() {
    $maximum = 40;
    $current = WC()->cart->subtotal;
    if (sizeof(WC()->cart->get_cart()) !== 0) {
        if ($woocommerce->cart->total < $maximum ) {
            if ( $current < $maximum ) {
                ob_start();
                echo '<div class="woocommerce-message">Få din ordre tilsendt gratis hvis du bestiller for ' . ($maximum - $current) . ' kr. mere!</div>';
                $output = ob_get_clean();
                return $output;
            }
        }
    }
}
add_action( 'woocommerce_before_cart', 'cart_notice' );
add_shortcode( 'cart_notice_sc', 'cart_notice' );
?>


The error says in line 5002 which is from    if ($woocommerce->cart->total < $maximum )