Session Cookie Cart Discount

add_action( 'template_redirect', function() {

	// Front End Only
	if( is_admin() ) {
		return;
	}

	// Handle Coupon Requests
	$coupon_code = isset( $_GET['coupon_code'] )
		? strtolower( sanitize_text_field( $_GET['coupon_code'] ) ) : '';

	// Require Coupon To Continue
	if( ! $coupon_code ) {
		return;
	}

	// Require WooCommerce
	if( ! class_exists( 'WooCommerce' ) ) {
		return;
	}

	// Setup Woo Session Cookie
	if( isset( WC()->session ) && ! WC()->session->has_session() ) {
		WC()->session->set_customer_session_cookie( true );
	}

	// Save To Woo Session Cookie
	WC()->session->set( 'ccom_coupon', $coupon_code );

} );

add_action( 'woocommerce_cart_calculate_fees', function( $cart ) {

	// Skip Admin Non AJAX
	if( is_admin() && ! defined( 'DOING_AJAX' ) ) {
		return;
	}

	// Setup Woo Session Cookie
	if( isset( WC()->session ) && ! WC()->session->has_session() ) {
		WC()->session->set_customer_session_cookie( true );
	}

	// Handle Session Coupon
	switch( WC()->session->get( 'ccom_coupon' ) ) {

		case '10-pct-off':
			$cart->add_fee(
				'Special Discount',
				-0.1 * (float) $cart->get_subtotal()
			);
			break;

	}

} );