Prestashop: Calculate the shipping cost by grouping products by supplier

Cart.php

<?php

/**
 * Return package shipping cost
 *
 * @param integer $id_carrier Carrier ID (default : current carrier)
 * @param booleal $use_tax
 * @param Country $default_country
 * @param Array $product_list
 * @param array $product_list List of product concerned by the shipping. If null, all the product of the cart are used to calculate the shipping cost
 *
 * @return float Shipping total
 */
public function getPackageShippingCost($id_carrier = null, $use_tax = true, Country $default_country = null, $product_list = null, $id_zone = null)
{
	if ($this->isVirtualCart())
		return 0;

	if (!$default_country)
		$default_country = Context::getContext()->country;

	$complete_product_list = $this->getProducts();
	if (is_null($product_list))
		$products = $complete_product_list;
	else
		$products = $product_list;

	if (Configuration::get('PS_TAX_ADDRESS_TYPE') == 'id_address_invoice')
		$address_id = (int)$this->id_address_invoice;
	elseif (count($product_list))
	{
		$prod = current($product_list);
		$address_id = (int)$prod['id_address_delivery'];
	}
	else
		$address_id = null;
	if (!Address::addressExists($address_id))
		$address_id = null;

	$cache_id = 'getPackageShippingCost_'.(int)$this->id.'_'.(int)$address_id.'_'.(int)$id_carrier.'_'.(int)$use_tax.'_'.(int)$default_country->id;
	if ($products)
		foreach ($products as $product)
			$cache_id .= '_'.(int)$product['id_product'].'_'.(int)$product['id_product_attribute'];

	if (Cache::isStored($cache_id))
		return Cache::retrieve($cache_id);

	// Order total in default currency without fees
	$order_total = $this->getOrderTotal(true, Cart::ONLY_PHYSICAL_PRODUCTS_WITHOUT_SHIPPING, $product_list);

	// Start with shipping cost at 0
	$shipping_cost = 0;
	// If no product added, return 0
	if (!count($products))
	{
		Cache::store($cache_id, $shipping_cost);
		return $shipping_cost;
	}

	if (!isset($id_zone))
	{
		// Get id zone
		if (!$this->isMultiAddressDelivery()
			&& isset($this->id_address_delivery) // Be carefull, id_address_delivery is not usefull one 1.5
			&& $this->id_address_delivery
			&& Customer::customerHasAddress($this->id_customer, $this->id_address_delivery
		))
			$id_zone = Address::getZoneById((int)$this->id_address_delivery);
		else
		{
			if (!Validate::isLoadedObject($default_country))
				$default_country = new Country(Configuration::get('PS_COUNTRY_DEFAULT'), Configuration::get('PS_LANG_DEFAULT'));

			$id_zone = (int)$default_country->id_zone;
		}
	}

	if ($id_carrier && !$this->isCarrierInRange((int)$id_carrier, (int)$id_zone))
		$id_carrier = '';

	if (empty($id_carrier) && $this->isCarrierInRange((int)Configuration::get('PS_CARRIER_DEFAULT'), (int)$id_zone))
		$id_carrier = (int)Configuration::get('PS_CARRIER_DEFAULT');

	$total_package_without_shipping_tax_inc = $this->getOrderTotal(true, Cart::BOTH_WITHOUT_SHIPPING, $product_list);
	if (empty($id_carrier))
	{
		if ((int)$this->id_customer)
		{
			$customer = new Customer((int)$this->id_customer);
			$result = Carrier::getCarriers((int)Configuration::get('PS_LANG_DEFAULT'), true, false, (int)$id_zone, $customer->getGroups());
			unset($customer);
		}
		else
			$result = Carrier::getCarriers((int)Configuration::get('PS_LANG_DEFAULT'), true, false, (int)$id_zone);

		foreach ($result as $k => $row)
		{
			if ($row['id_carrier'] == Configuration::get('PS_CARRIER_DEFAULT'))
				continue;

			if (!isset(self::$_carriers[$row['id_carrier']]))
				self::$_carriers[$row['id_carrier']] = new Carrier((int)$row['id_carrier']);

			$carrier = self::$_carriers[$row['id_carrier']];

			// Get only carriers that are compliant with shipping method
			if (($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT && $carrier->getMaxDeliveryPriceByWeight((int)$id_zone) === false)
			|| ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_PRICE && $carrier->getMaxDeliveryPriceByPrice((int)$id_zone) === false))
			{
				unset($result[$k]);
				continue;
			}

			// If out-of-range behavior carrier is set on "Desactivate carrier"
			if ($row['range_behavior'])
			{
				$check_delivery_price_by_weight = Carrier::checkDeliveryPriceByWeight($row['id_carrier'], $this->getTotalWeight(), (int)$id_zone);

				$total_order = $total_package_without_shipping_tax_inc;
				$check_delivery_price_by_price = Carrier::checkDeliveryPriceByPrice($row['id_carrier'], $total_order, (int)$id_zone, (int)$this->id_currency);

				// Get only carriers that have a range compatible with cart
				if (($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT && !$check_delivery_price_by_weight)
				|| ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_PRICE && !$check_delivery_price_by_price))
				{
					unset($result[$k]);
					continue;
				}
			}

			if ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT)
				$shipping = $carrier->getDeliveryPriceByWeight($this->getTotalWeight($product_list), (int)$id_zone);
			else
				$shipping = $carrier->getDeliveryPriceByPrice($order_total, (int)$id_zone, (int)$this->id_currency);

			if (!isset($min_shipping_price))
				$min_shipping_price = $shipping;

			if ($shipping <= $min_shipping_price)
			{
				$id_carrier = (int)$row['id_carrier'];
				$min_shipping_price = $shipping;
			}
		}
	}

	if (empty($id_carrier))
		$id_carrier = Configuration::get('PS_CARRIER_DEFAULT');

	if (!isset(self::$_carriers[$id_carrier]))
		self::$_carriers[$id_carrier] = new Carrier((int)$id_carrier, Configuration::get('PS_LANG_DEFAULT'));

	$carrier = self::$_carriers[$id_carrier];

	// No valid Carrier or $id_carrier <= 0 ?
	if (!Validate::isLoadedObject($carrier))
	{
		Cache::store($cache_id, 0);
		return 0;
	}

	if (!$carrier->active)
	{
		Cache::store($cache_id, $shipping_cost);
		return $shipping_cost;
	}

	// Free fees if free carrier
	if ($carrier->is_free == 1)
	{
		Cache::store($cache_id, 0);
		return 0;
	}

	// Select carrier tax
	if ($use_tax && !Tax::excludeTaxeOption())
	{
		$address = Address::initialize((int)$address_id);
		$carrier_tax = $carrier->getTaxesRate($address);
	}

	$configuration = Configuration::getMultiple(array(
		'PS_SHIPPING_FREE_PRICE',
		'PS_SHIPPING_HANDLING',
		'PS_SHIPPING_METHOD',
		'PS_SHIPPING_FREE_WEIGHT'
	));

	// Free fees
	$free_fees_price = 0;
	if (isset($configuration['PS_SHIPPING_FREE_PRICE']))
		$free_fees_price = Tools::convertPrice((float)$configuration['PS_SHIPPING_FREE_PRICE'], Currency::getCurrencyInstance((int)$this->id_currency));
	$orderTotalwithDiscounts = $this->getOrderTotal(true, Cart::BOTH_WITHOUT_SHIPPING, null, null, false);
	if ($orderTotalwithDiscounts >= (float)($free_fees_price) && (float)($free_fees_price) > 0)
	{
		Cache::store($cache_id, $shipping_cost);
		return $shipping_cost;
	}

	if (isset($configuration['PS_SHIPPING_FREE_WEIGHT'])
		&& $this->getTotalWeight() >= (float)$configuration['PS_SHIPPING_FREE_WEIGHT']
		&& (float)$configuration['PS_SHIPPING_FREE_WEIGHT'] > 0)
	{
		Cache::store($cache_id, $shipping_cost);
		return $shipping_cost;
	}

	// Get shipping cost using correct method
	if ($carrier->range_behavior)
	{
		if(!isset($id_zone))
		{
			// Get id zone
			if (isset($this->id_address_delivery)
				&& $this->id_address_delivery
				&& Customer::customerHasAddress($this->id_customer, $this->id_address_delivery))
				$id_zone = Address::getZoneById((int)$this->id_address_delivery);
			else
				$id_zone = (int)$default_country->id_zone;
		}

		if (($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT && !Carrier::checkDeliveryPriceByWeight($carrier->id, $this->getTotalWeight(), (int)$id_zone))
		|| ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_PRICE && !Carrier::checkDeliveryPriceByPrice($carrier->id, $total_package_without_shipping_tax_inc, $id_zone, (int)$this->id_currency)
		))
			$shipping_cost += 0;
		else
		{
			if ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT) {

                $suppliers = Array();
                $weight_per_supplier = Array();
                $products_per_suppliers = Array();

                foreach ($products as $product)
                {
                    $product_supplier = $product['id_supplier'];
                    if (!in_array($product_supplier, $suppliers)) {
                        $suppliers[] = $product_supplier;
                    }
                    $products_per_suppliers[$product_supplier][] = $product;
                    $weight_per_supplier[$product_supplier] += $product['weight'];
                }

                foreach ($products_per_suppliers as $products_per_supplier)
                {
                    $shipping_cost += $carrier->getDeliveryPriceByWeight($this->getTotalWeight($products_per_supplier), $id_zone);
                }
            } else { // by price
				$shipping_cost += $carrier->getDeliveryPriceByPrice($order_total, $id_zone, (int)$this->id_currency);
            }
		}
	}
	else
	{
		if ($carrier->getShippingMethod() == Carrier::SHIPPING_METHOD_WEIGHT) {
            $shipping_cost += $carrier->getDeliveryPriceByWeight($this->getTotalWeight($product_list), $id_zone);
        } else {
            $shipping_cost += $carrier->getDeliveryPriceByPrice($order_total, $id_zone, (int)$this->id_currency);
        }
	}
	// Adding handling charges
	if (isset($configuration['PS_SHIPPING_HANDLING']) && $carrier->shipping_handling)
		$shipping_cost += (float)$configuration['PS_SHIPPING_HANDLING'];

	// Additional Shipping Cost per product
	foreach ($products as $product)
		if (!$product['is_virtual'])
			$shipping_cost += $product['additional_shipping_cost'] * $product['cart_quantity'];

	$shipping_cost = Tools::convertPrice($shipping_cost, Currency::getCurrencyInstance((int)$this->id_currency));

	//get external shipping cost from module
	if ($carrier->shipping_external)
	{
		$module_name = $carrier->external_module_name;
		$module = Module::getInstanceByName($module_name);

		if (Validate::isLoadedObject($module))
		{
			if (array_key_exists('id_carrier', $module))
				$module->id_carrier = $carrier->id;
			if ($carrier->need_range)
				if (method_exists($module, 'getPackageShippingCost'))
					$shipping_cost = $module->getPackageShippingCost($this, $shipping_cost, $products);
				else
					$shipping_cost = $module->getOrderShippingCost($this, $shipping_cost);
			else
				$shipping_cost = $module->getOrderShippingCostExternal($this);

			// Check if carrier is available
			if ($shipping_cost === false)
			{
				Cache::store($cache_id, false);
				return false;
			}
		}
		else
		{
			Cache::store($cache_id, false);
			return false;
		}
	}

	// Apply tax
	if ($use_tax && isset($carrier_tax))
		$shipping_cost *= 1 + ($carrier_tax / 100);

	$shipping_cost = (float)Tools::ps_round((float)$shipping_cost, 2);
	Cache::store($cache_id, $shipping_cost);

	return $shipping_cost;
}
?>