How to programatically send order shipped email

-- HikaShop version -- : 2.6.1
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.3.10
-- Browser(s) name and version -- : Firefox 38.0.5

I'm aware of the backend feature to change an order's status to 'shipped' and it will load a modal, which will ask if you want to send an email.
However, how can I make a PHP call to this same exact function? I want to be able to change the order's status and send an email through a plugin. This plugin is inside the Hikashop plugin group.

I did some more research and found the following options:

• hikashopPaymentPlugin->modifyOrder. However, my plugin is not a derived class of hikashopPlugin
• OrderController->savechangestatus. However, this relies on POST data, which I don't have from a plugin call

Thank you for replying. I did some tinkering and reached this solution:

// Load order
$orderClass = hikashop_get('class.order');
$order = $orderClass->loadFullOrder($orderid);

// These properties should be removed before attempting to save the order
unset($order->order_subtotal);
unset($order->order_subtotal_no_vat);

// Change order status
$order->order_status = 'shipped';

// Set email to user's language
$langparams = json_decode($order->customer->params);
$lang = isset($langparams->language) ? $langparams->language : null;
$langObj = JFactory::getLanguage($lang);
$langObj->load('com_hikashop', JPATH_SITE);

// Set new history entry
$order->history = new stdClass();
$order->history->history_notified = '1';
$order->history->history_type = 'shipment';

// Save order to DB
$orderClass->save($order);