$storeId = Mage::app()->getStore()->getStoreId();
try {
$customer_id = $this->getRequest()->getParam('customer_id');
$selected_product_details = $this->getRequest()->getParam('selected_product_details');
$firstname = $this->getRequest()->getParam('firstname');
$lastname = $this->getRequest()->getParam('lastname');
$email = $this->getRequest()->getParam('email');
$street = $this->getRequest()->getParam('street');
$mobile = $this->getRequest()->getParam('mobile');

if ($customer_id == '') {
    $store = Mage::app()->getStore();
    $customer = Mage::getModel("customer/customer");
    $customer->setWebsiteId($websiteId)
            ->setStore($store)
            ->setFirstname($firstname)
            ->setLastname($lastname)
            ->setEmail($email)
            ->setPassword('123456');
    $customer->save();
    $customer_id = $customer->getCustomerId();
} else {
    $customer = Mage::getModel('customer/customer')->load($customer_id);
}
$product_details = json_decode($selected_product_details, true);
$websiteId = Mage::app()->getWebsite()->getId();
// Start New Sales Order Quote
$quote = Mage::getModel('sales/quote')
        ->setStoreId($storeId);
// Set Sales Order Quote Currency
$quote->setCurrency($order->AdjustmentAmount->currencyID);
// Assign Customer To Sales Order Quote
$quote->assignCustomer($customer);
// Configure Notification
$quote->setSendCconfirmation(1);
foreach ($product_details as $_products) {
    $productId = $_products['productId'];
    $qty = $_products['qty'];
    $product = Mage::getModel('catalog/product')->load($productId);
    $quote->addProduct($product, new Varien_Object(array('qty' => $qty)));
}
// Set Sales Order Billing Address
$billingAddress = $quote->getBillingAddress()->addData(array(
    'customer_address_id' => '',
    'prefix' => '',
    'firstname' => $firstname,
    'middlename' => '',
    'lastname' => $lastname,
    'suffix' => '',
    'company' => '',
    'street' => $street,
    'telephone' => $mobile,
    'vat_id' => '',
    'save_in_address_book' => 1
));
// Set Sales Order Shipping Address
$shippingAddress = $quote->getShippingAddress()->addData(array(
    'customer_address_id' => '',
    'prefix' => '',
    'firstname' => $firstname,
    'middlename' => '',
    'lastname' => $lastname,
    'suffix' => '',
    'company' => '',
    'street' => $street,
    'telephone' => $mobile,
    'vat_id' => '',
    'save_in_address_book' => 1
));

if ($shippingPrice == 0) {
    $shippingAddress->setCollectShippingRates(true)
            ->collectShippingRates()
            ->setShippingMethod('freeshipping_freeshipping')
            ->setPaymentMethod('cashondelivery');
} else {
    $shippingAddress->setCollectShippingRates(true)
            ->collectShippingRates()
            ->setShippingMethod('flatrate_flatrate')
            ->setPaymentMethod('cashondelivery');
}

//Fire event sales_quote_collect_totals_after Before ->collectTotals->save();

$quote->getPayment()->importData(array('method' => 'cashondelivery'));
$quote->collectTotals->save();

// Create Order From Quote
$service = Mage::getModel('sales/service_quote', $quote);
$service->submitAll();
$orderId = $service->getOrder()->getRealOrderId();
// Resource Clean-Up
$quote = $customer = $service = null;
$this->createOrderInvoice($orderId);

$message = $this->__('Ordered Created Successfully');
$success = 1;

//send mail when placing order
$order_mail = new Mage_Sales_Model_Order();
$order_mail->loadByIncrementId($orderId);
$order_mail->sendNewOrderEmail();

$result = array("success" => $success, "message" => $message, "order_id" => $orderId);
$this->getResponse()->setBody(Mage::helper('core')->jsonEncode($result));

} catch (Exception $ex) {
      $message = $this->__('Something went wrong. Please try again.');
      $success = 0;
      $result = array("success" => $success, "message" => $message);
      $this->getResponse()->setBody(Mage::helper('core')->jsonEncode($result));

      return false;
}

<modules>
    <Assel_StoreOwners>
        <version>0.1.0</version>
    </Assel_StoreOwners>
</modules>

<global>
    <blocks>
        <storeowners>
            <class>Assel_StoreOwners_Block</class>
        </storeowners>
    </blocks>

    <helpers>
        <storeowners>
            <class>Assel_StoreOwners_Helper</class>
        </storeowners>
    </helpers>

    <events>
        <sales_quote_collect_totals_after>
            <observers>
                <set_custom_discount>
                    <type>singleton</type>
                    <class>Assel_StoreOwners_Model_Observer</class>
                    <method>setDiscount</method>
                </set_custom_discount>
            </observers>
        </sales_quote_collect_totals_after>
    </events>
</global>

function setDiscount($observer) {
            $quote=$observer->getEvent()->getQuote();
            $quoteid=$quote->getId();
            $customer_id = $quote->getCustomerId();
     }