Override Class Cart for Prestashop 1.6.0.14 to calculate shipping cost grouping products by supplier

Cart.php

<?php

class Cart extends CartCore
{
	/**
	 * 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;

		if (!is_null($product_list))
			foreach ($product_list as $key => $value)
				if ($value['is_virtual'] == 1)
					unset($product_list[$key]);

		$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"
print "Git3 ".$this->getTotalWeight();
				if ($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;
			}

			$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'];
			}

			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) {
					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;
	}

	/**
	* Return cart weight
	* @return float Cart weight
	*/
	public function getTotalWeight($products = null)
	{
		if (!is_null($products))
		{
			$total_weight = 0;
			
			$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;

				if (!isset($product['weight_attribute']) || is_null($product['weight_attribute']))
					$weight_per_supplier[$product_supplier] += $product['weight'] * $product['cart_quantity'];
				else
					$weight_per_supplier[$product_supplier] += $product['weight_attribute'] * $product['cart_quantity'];
			}
			$total_weight = max($weight_per_supplier);
			return $total_weight;
		}

		if (!isset(self::$_totalWeight[$this->id]))
		{
			if (Combination::isFeatureActive())
				$weight_product_with_attribute = Db::getInstance()->getValue('
				SELECT SUM((p.`weight` + pa.`weight`) * cp.`quantity`) as nb
				FROM `'._DB_PREFIX_.'cart_product` cp
				LEFT JOIN `'._DB_PREFIX_.'product` p ON (cp.`id_product` = p.`id_product`)
				LEFT JOIN `'._DB_PREFIX_.'product_attribute` pa ON (cp.`id_product_attribute` = pa.`id_product_attribute`)
				WHERE (cp.`id_product_attribute` IS NOT NULL AND cp.`id_product_attribute` != 0)
				AND cp.`id_cart` = '.(int)$this->id.' GROUP BY p.`id_supplier` ORDER BY nb DESC LIMIT 1');
			else
				$weight_product_with_attribute = 0;

			$weight_product_without_attribute = Db::getInstance()->getValue('
			SELECT SUM(p.`weight` * cp.`quantity`) as nb
			FROM `'._DB_PREFIX_.'cart_product` cp
			LEFT JOIN `'._DB_PREFIX_.'product` p ON (cp.`id_product` = p.`id_product`)
			WHERE (cp.`id_product_attribute` IS NULL OR cp.`id_product_attribute` = 0)
			AND cp.`id_cart` = '.(int)$this->id.' GROUP BY p.`id_supplier` ORDER BY nb DESC LIMIT 1');
			
			self::$_totalWeight[$this->id] = round((float)$weight_product_with_attribute + (float)$weight_product_without_attribute, 3);
		}
		return self::$_totalWeight[$this->id];
	}

}
?>