woocommerce gateway process payment
public function process_payment( $order_id ) {
$order = wc_get_order( $order_id );
// Mark as on-hold (we're awaiting the payment)
$order->update_status( 'on-hold', __( 'Awaiting offline payment', 'wc-gateway-offline' ) );
// Reduce stock levels
$order->reduce_order_stock();
// Remove cart
WC()->cart->empty_cart();
// Return thankyou redirect
return array(
'result' => 'success',
'redirect' => $this->get_return_url( $order )
);
}