B_DeleteGoogleProductTask.php

<?php

namespace Craft;

class B_DeleteGoogleProductTask extends BaseTask
{

	public function getDescription ()
	{
		return 'Updating Google Shopping';
	}

	public function getTotalSteps ()
	{
		return count($this->getSettings()->productIds);
	}

	public function runStep ($step)
	{
		$product = craft()->commerce_products->getProductById($this->getSettings()->productIds[$step]);

		try {
			craft()->b_google->onProductDelete($product);
		} catch (\Exception $e) {}

		return true;
	}

	// Protected
	// =========================================================================

	protected function defineSettings ()
	{
		return [
			'productIds' => AttributeType::Mixed
		];
	}

}

B_GoogleService.php

<?php

namespace Craft;

set_error_handler(function($errno, $errstr, $errfile, $errline ){
	throw new \ErrorException($errstr, $errno, 0, $errfile, $errline);
});

class B_GoogleService extends BaseApplicationComponent
{

	private $_client;
	private $_service;
	private $_keyFilename = '[NameOfKeyFile]';
	private $_merchantId = '[MerchantId]';

	private function _initGoogleClient ()
	{
		if (!empty($this->_client) && !empty($this->_service)) return;

		// This assumes the keyfile is in the `craft/config/` directory
		// (i.e. `craft/config/myKeyFile.json`)
		$path = CRAFT_CONFIG_PATH;
		putenv("GOOGLE_APPLICATION_CREDENTIALS={$path}{$this->_keyFilename}.json");

		$this->_client = new \Google_Client();
		$this->_client->useApplicationDefaultCredentials();
		$this->_client->setScopes(['https://www.googleapis.com/auth/content']);

		$this->_service = new \Google_Service_ShoppingContent($this->_client);
	}

	/**
	 * @param Commerce_ProductModel $product
	 *
	 * @return bool
	 */
	public function onProductSave (Commerce_ProductModel $product)
	{
		$this->_initGoogleClient();
		if (
			!filter_var($product->availableOnline, FILTER_VALIDATE_BOOLEAN)
			|| !$product->enabled
		) return true;

		foreach ($product->variants as $variant) {

			$gProduct = new \Google_Service_ShoppingContent_Product();
			$gProduct->setId($product->slug . '_' . $variant->id);


			// If we don't have a valid GTIN number, skip since Google won't allow it.
			if (!$this->_checkGTIN($variant->sku))
				continue;

			$gProduct->setGtin($variant->sku);

			$gProduct->setTitle($product->getTitle());
			$gProduct->setDescription(strip_tags($product->productDetails));
			$gProduct->setProductType($product->productCategory->last()->getTitle());
			$url = $product->getUrl();
			if (!$variant->isDefault)
				$url .= '/' . $variant->id;
			$gProduct->setLink($url);
			$gProduct->setImageLink($variant->gallery->first()->getUrl('gallery'));
			$gProduct->setCondition('new');
			$gProduct->setAvailability($variant->stock > 0 || $variant->unlimitedStock ? 'in stock' : 'out of stock');

			// If we don't have a brand, skip since Google won't allow it.
			if (!$product->brand->first())
				continue;
			$gProduct->setBrand($product->brand->first()->getTitle());


			$gProduct->setChannel($product->availableOnline ? 'online' : 'local');
			$gProduct->setContentLanguage('EN');
			$gProduct->setOfferId("P{$product->id}V{$variant->id}");
			$gProduct->setTargetCountry('GB');


			// TODO: Find a way to not have to hard-code shipping values
			$shipping_price = new \Google_Service_ShoppingContent_Price();
			if ($product->getShippingCategory()->handle == 'aquaOak') {
				$shipping_price->setValue(50.00);
			} else {
				$shipping_price->setValue(
					$variant->price > 49.99 || $product->freeShipping
						? '0.00'
						: '5.95'
				);
			}
			$shipping_price->setCurrency('GBP');

			$shipping = new \Google_Service_ShoppingContent_ProductShipping();
			$shipping->setPrice($shipping_price);
			$shipping->setCountry('GB');
			$shipping->setService('Standard shipping');

			$gProduct->setShipping([$shipping]);

			$price = new \Google_Service_ShoppingContent_Price();
			$price->setCurrency('GBP');
			$price->setValue($variant->price);

			$gProduct->setPrice($price);


			if ($variant->getOnSale()) {
				$salePrice = new \Google_Service_ShoppingContent_Price();
				$salePrice->setCurrency('GBP');
				$salePrice->setValue($variant->getSalePrice());

				$gProduct->setSalePrice($salePrice);
			}


			try {
				$this->_service->products->insert(
					$this->_merchantId,
					$gProduct,
					['dryRun' => craft()->config->get('devMode')]
				);
			}
			catch (\Google_Service_Exception $e)
			{
				$message = "[Product ID {$product->id}] [Variant ID {$variant->id}] ";
				if (!empty($e->getErrors()) && array_key_exists('message', $e->getErrors()[0]))
					$message .= $e->getErrors()[0]['message'];

				BPlugin::log(print_r($message, true), LogLevel::Error, true);
			}

		}

		return true;
	}

	/**
	 * @param Commerce_ProductModel $product
	 *
	 * @return bool
	 */
	public function onProductDelete (Commerce_ProductModel $product)
	{
		$this->_initGoogleClient();
		if (!$product->availableOnline) return true;

		foreach ($product->variants as $variant) {
			try {
				$this->_service->products->delete($this->_merchantId, $product->slug . '_' . $variant->id);
			}
			catch (\Exception $e)
			{
				BPlugin::log(print_r($e, true), LogLevel::Error, true);
				return true; // Fail silently to stop clogging up tasks
			}
		}

		return true;
	}

	// Private
	// =========================================================================

	# Check length of barcode for validity
	function _checkGTIN ($gtin) {

		# Check that GTIN provided is a certain length
		if (!$this->_checkBasics($gtin))
			return false;

		# Define fixed variables
		$CheckDigitArray = [];
		$gtinMaths = [3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3];
		$modifier = 17 - (strlen($gtin) - 1);  // Gets the position to place first digit in array
		$gtinCheckDigit = substr($gtin, -1); // Get provided check digit
		$BarcodeArray = str_split($gtin);  // Split barcode at each digit into array
		$gtinLength = strlen($gtin);
		$tmpCheckDigit = 0;
		$tmpCheckSum = 0;
		$tmpMath = 0;

		# Run through and put digits into multiplication table
		for ($i=0; $i < ($gtinLength - 1); $i++) {
			$CheckDigitArray[$modifier + $i] = $BarcodeArray[$i];  // Add barcode digits to Multiplication Table

			// Catch if part of GTIN is not a number
			if (!is_numeric($CheckDigitArray[$modifier + $i]))
				return false;
		}

		# Calculate "Sum" of barcode digits
		for ($i=$modifier; $i < 17; $i++) {
			$tmpCheckSum += ($CheckDigitArray[$i] * $gtinMaths[$i]);
		}

		# Difference from Rounded-Up-To-Nearest-10 - Fianl Check Digit Calculation
		$tmpCheckDigit = (ceil($tmpCheckSum / 10) * 10) - $tmpCheckSum;

		# Check if last digit is same as calculated check digit
		if ($gtinCheckDigit == $tmpCheckDigit)
			return true;
		return false;
	}

	# Checks the length of the GTIN
	function _checkBasics ($gtin) {
		# Check length is ok
		if (strlen($gtin) < 8 || strlen($gtin) > 14)
			return false;

		# Check whether is a number
		preg_match("/\d+/", $gtin, $m, PREG_OFFSET_CAPTURE, 0);
		if (empty($m))
			return false;

		# Is valid, return true
		return true;
	}

}

B_UpdateGoogleProductTask.php

<?php

namespace Craft;

class B_UpdateGoogleProductTask extends BaseTask
{

	public function getDescription ()
	{
		return 'Updating Google Shopping';
	}

	public function getTotalSteps ()
	{
		return count($this->getSettings()->productIds);
	}

	public function runStep ($step)
	{
		$product = craft()->commerce_products->getProductById($this->getSettings()->productIds[$step]);

		try {
			craft()->b_google->onProductSave($product);
		} catch (\Exception $e) {}

		return true;
	}

	// Protected
	// =========================================================================

	protected function defineSettings ()
	{
		return [
			'productIds' => AttributeType::Mixed
		];
	}

}

BPlugin.php

<?php

// Stripped down for brevity
class BPlugin {
	
	public function init () {
		// Trigger Google Shopping updates
		// =====================================================================

		if (!craft()->config->get('devMode')) {
			craft()->on('commerce_products.onSaveProduct',
				function (Event $event) {
					craft()->tasks->createTask('B_UpdateGoogleProduct', null, [
						'productIds' => [$event->params['product']->id],
					]);
				});

			craft()->on('commerce_products.onBeforeDeleteProduct',
				function (Event $event) {
					craft()->tasks->createTask('B_DeleteGoogleProduct', null, [
						'productIds' => [$event->params['product']->id],
					]);
				});

			craft()->on('commerce_variants.onOrderVariant',
				function (Event $event) {
					craft()->tasks->createTask('B_UpdateGoogleProduct', null, [
						'productIds' => [$event->params['variant']->productId],
					]);
				});
		}
	}
	
}