Observer.php

<?php

/**
 * Open Tools Ordernumber module for Magento
 *
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * @category   OpenTools
 * @package    Ordernumber
 * @copyright  Copyright (c) 2010 Fooman Limited (http://www.fooman.co.nz)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */
class OpenTools_Ordernumber_Model_Observer extends Mage_Core_Model_Abstract
{
     public function _construct()
     {
         parent::_construct();
         $this->_init('ordernumber/ordernumber');
     }
 
    protected $_dbModel = null;
    protected function _getModel() {
        return Mage::getModel('opentools_ordernumber/ordernumber');
    }
    
    public function getModel() {
        if (is_null($this->_dbModel)) 
            $this->_dbModel = $this->_getModel();
        return $this->_dbModel;
    }

    // This trigger is called directly after the increment ID is reserved for an order
    // TODO: Ideally, we would overwrite the reserveOrderId function!
    //       Then magento would not create/reserve an order in the first place
    public function sales_model_service_quote_submit_before ($observer) {
        $order = $observer->getEvent()->getOrder();
        return $this->handle_new_number('order', $order, $order);
    }
    public function sales_order_save_before ($observer) {
        $order = $observer->getEvent()->getOrder();
        return $this->handle_new_number('order', $order, $order);
    }

    public function sales_order_invoice_save_before ($observer) {
        $invoice = $observer->getEvent()->getInvoice();
        return $this->handle_new_number('invoice', $invoice, $invoice->getOrder());
    }

    public function sales_order_shipment_save_before ($observer) {
        $shipment = $observer->getEvent()->getShipment();
        return $this->handle_new_number('shipment', $shipment, $shipment->getOrder());
    }

    public function sales_order_creditmemo_save_before ($observer) {
        $creditmemo = $observer->getEvent()->getCreditmemo();
        return $this->handle_new_number('creditmemo', $creditmemo, $creditmemo->getOrder());
    }

    public function handle_new_number ($nrtype, $object, $order) {
        $storeId = $order->getStore()->getStoreId();
        $cfgprefix = 'ordernumber/'.$nrtype.'numbers';
        $enabled = Mage::getStoreConfig($cfgprefix.'/active', $storeId);

        if ($enabled && !$object->getId() && !$object->getOrdernumberProcessed()) {
            // This trigger might be called twice, so ignore it the second time!
            $object->setOrdernumberProcessed(true);

            $format = Mage::getStoreConfig($cfgprefix.'/format', $storeId);
            $global = Mage::getStoreConfig($cfgprefix.'/global', $storeId);
            $digits = Mage::getStoreConfig($cfgprefix.'/digits', $storeId);

            // First, replace all variables:
            $helper = Mage::helper('ordernumber');
            $info = array('order'=>$order, $nrtype=>$object);
            $nr = $helper->replace_fields ($format, $nrtype, $info);

            // Split at a | to get the number format and a possibly different counter increment format
            // If a separate counter format is given after the |, use it, otherwise reuse the number format itself as counter format
            $parts = explode ("|", $nr);
            $format = $parts[0];
            $counterfmt = ($global==1)?"":$parts[(count($parts)>1)?1:0];
            
            // Now find the next counter that does not lead to duplicate 
            $newnumber = null;
            $model = $this->getModel();
            
            $count = 0;
            $created = false;
            // Make up to 150 attempts to create a number...
            while (empty($newnumber) && (count<150)) { 
                $count += 1;

                // Find the next counter value
                $count = $model->getCounterValueIncremented($nrtype, $counterfmt);
                $newnumber = str_replace ("#", sprintf('%0' . (int)$digits . 's', $count), $format);
                
                // Check whether that number is already in use. If so, attempt to create the next number:
                $modelname=($nrtype=='order') ? 'sales/order' : ('sales/order_'.$nrtype);
                $collection = Mage::getModel($modelname)->getCollection()->addFieldToFilter('increment_id', $newnumber);
                if ($collection->getAllIds()) {
                    Mage::Log("$nrtype number $newnumber already in use, trying again", null, 'ordernumber.log');
                    //number already exists => next attempt in the loop
                    $newnumber = null;
                } else {
                    $object->setIncrementId($newnumber);
                    $created = true;
                }
            }
            if (!$created) {
                Mage::Log("Unable to create $nrtype number for counter format $nr (name $counterfmt)...", null, 'ordernumber.log');
            }
        }
    }

}