Generating EDI 850 Purchase Order Documents in Magento

<?xml version="1.0"?>
<config>
<modules>
<NeptuneWeb_ExportEdiOrder>
<version>0.1</version>
</NeptuneWeb_ExportEdiOrder>
</modules>
<global>
<models>
<nwExportEdiOrder>
<class>NeptuneWeb_ExportEdiOrder_Model</class>
</nwExportEdiOrder>
</models>
<events>
<sales_order_invoice_pay>
<observers>
<nwExportEdiOrder>
<type>singleton</type>
<class>nwExportEdiOrder/observer</class>
<method>sales_order_invoice_pay</method>
</nwExportEdiOrder>
</observers>
</sales_order_invoice_pay>
</events>
</global>
</config>

class NeptuneWeb_ExportEdiOrder_Model_Observer {
public function sales_order_invoice_pay($observer) {

function cleanForEdi($string) {
# replace `
$string = preg_replace('/`/', '', $string);
# replace the following characters * ~ >
return preg_replace('/[\*~>]/', '-', $string);
}

# gather necessary variables
$invoice = $observer->getEvent()->getInvoice();
$order = $invoice->getOrder();
$storeId = $order->getStoreId();
$orderItems = $order->getAllItems();
$orderId = $order->getIncrementId();
$customer = Mage::getModel('customer/customer')->load($order->getCustomerId());
$streetBA=$order->getBillingAddress()->getStreet();
$streetSA=$order->getShippingAddress()->getStreet();
$shippingMethod = $order->getShippingMethod();
# format is carrier_method
# eg: fedex_FEDEXGROUND
$data = explode('_', $shippingMethod);
$shippingCarrier = $data[0];
$shippingCarrierMethod = $data[1];

$ServiceLevelCode = "";
switch ($shippingCarrierMethod) {
case "FEDEXGROUND":
$ServiceLevelCode = "SG";
break;
case "FEDEX2DAY":
$ServiceLevelCode = "SE";
break;
}

$date = date("ymd");
$date2 = date("Ymd");
$time = date("Hi");
$InterchangeSenderID = "MYWEB1234";
$InterchangeSenderIDISA = "MYWEB1234 "; # must be 15 characters
$InterchangeReceiverID = "MYID12345678";
$InterchangeReceiverIDISA = "MYID12345678 "; # must be 15 characters
#$InterchangeControlNumber = $orderId; # need to be incremented, unique id - will use order id from magento
$InterchangeControlNumber = $order->getId(); # need to use id from the db because it must be numeric (and magento is creating numbers like 10000123-1)
# $InterchangeControlNumber must be 9 digits, need to pad with zeros
if (strlen($InterchangeControlNumber) < 9) {
$InterchangeControlNumber = str_pad($InterchangeControlNumber, 9, '0', STR_PAD_LEFT);
}
$PoNumber = $orderId; # order id from magento
$ProductionOrTest = "P";

# the entire ISA line must be 106 characters long
print "ISA*00* *00* *08*$InterchangeSenderIDISA*14*$InterchangeReceiverIDISA*$date*$time*:*00501*$InterchangeControlNumber*0*$ProductionOrTest*>~\n";
print "GS*PO*$InterchangeSenderID*$InterchangeReceiverID*$date2*$time*$InterchangeControlNumber*X*005010~\n";

$TransactionSetControlID = $InterchangeControlNumber;
$segmentCount = 1;

print "ST*850*$TransactionSetControlID~\n";
$segmentCount++;

$orderNumber = $PoNumber;
$orderDate = date("Ymd", strtotime($order->getCreatedAt()));

print "BEG*00*SA*$orderNumber**$orderDate~\n";
$segmentCount++;

# shipping method
print "TD5**2*FDEG**$shippingCarrierMethod*******$ServiceLevelCode~\n";
$segmentCount++;

$shipToName = cleanForEdi($order->getShippingAddress()->getFirstname() . " " . $order->getShippingAddress()->getLastname());
$customerId = $customer->getId(); # unique customer id

# get id for shipping address
$shippingAddressId = $order->getShippingAddress()->getId();
print "N1*ST*$shipToName*92*$shippingAddressId~\n";
$segmentCount++;

$address1 = cleanForEdi($streetSA[0]);
$address2 = cleanForEdi((count($streetSA)==2)?$streetSA[1]:'');
print "N3*$address1*$address2~\n";
$segmentCount++;

$city = cleanForEdi($order->getShippingAddress()->getCity());
$state = cleanForEdi($order->getShippingAddress()->getRegionCode());
$zip = cleanForEdi($order->getShippingAddress()->getPostcode());
$country = cleanForEdi($order->getShippingAddress()->getCountry());
print "N4*$city*$state*$zip*$country~\n";
$segmentCount++;

# phone must be 10 digits
$phone = cleanForEdi($order->getShippingAddress()->getTelephone());
$phone = preg_replace('/[^\d]/', '', $phone);
$phone = substr($phone, 0, 10);
print "PER*BD**TE*$phone~\n";
$segmentCount++;

foreach ($orderItems as $item) {
$qty = intval($item->getQtyOrdered());
$sku = cleanForEdi($item->getSku());

$unitPrice = sprintf("%.06f", ($item->getRowTotal() - $item->getDiscountAmount()) / $qty);
$total = sprintf("%.02f", $item->getRowTotal() - $item->getDiscountAmount());

print "PO1**$qty*EA*$unitPrice*LE*VN*$sku~\n";
$segmentCount++;

print "AMT*1*$total~\n";
$segmentCount++;
}

# line item for shipping
$totalShipping = sprintf("%.02f", $order->getShippingAmount() - $order->getShippingDiscountAmount());
print "PO1**1*EA*$totalShipping*LE*VN*SNHDL~\n";
$segmentCount++;

print "AMT*1*$totalShipping~\n";
$segmentCount++;

$NumberofDetailLines = count($orderItems) + 1;
print "CTT*$NumberofDetailLines~\n";
$segmentCount++;

$orderTotal = sprintf("%.02f", $order->getGrandTotal() - $order->getTaxAmount());
print "AMT*GV*$orderTotal~\n";
$segmentCount++;

print "SE*$segmentCount*$InterchangeControlNumber~\n";
print "GE*1*$InterchangeControlNumber~\n";
print "IEA*1*$InterchangeControlNumber~\n";

$string = ob_get_clean();
$ouputDirectory = "/tmp/edi-outgoing";
$outFile = $ouputDirectory . "/edi-". $orderId . ".txt";
$fp = fopen($outFile, "a");
fwrite($fp, $string);
fclose($fp);
}
}