.. rst-class:: outdated

Custom calculators
==================

.. danger::

   We're sorry but **this documentation section is outdated**. Please have that in mind when trying to use it.
   You can help us making documentation up to date via Sylius Github. Thank you!

Sylius ships with several default calculators, but you can easily register your own.

Simple calculators
------------------

All shipping cost calculators implement ``CalculatorInterface``. In our example we'll create a calculator which calls an external API to obtain the shipping cost.

.. code-block:: php

    <?php
    # src/Shipping/Calculator/DHLCalculator.php

    declare(strict_types=1);

    namespace App\Shipping\Calculator;

    use Sylius\Component\Shipping\Calculator\CalculatorInterface;
    use Sylius\Component\Shipping\Model\ShipmentInterface;

    final class DHLCalculator implements CalculatorInterface
    {
        /**
         * @var DHLService
         */
        private $dhlService;

        /**
         * @param DHLService $dhlService
         */
        public function __construct(DHLService $dhlService)
        {
            $this->dhlService = $dhlService;
        }

        /**
         * {@inheritdoc}
         */
        public function calculate(ShipmentInterface $subject, array $configuration): int
        {
            return $this->dhlService->getShippingCostForWeight($subject->getShippingWeight());
        }

        /**
         * {@inheritdoc}
         */
        public function getType(): string
        {
            return 'dhl';
        }
    }

Now, you need to register your new service in container and tag it with ``sylius.shipping_calculator``.

.. code-block:: yaml

    services:
        app.shipping_calculator.dhl:
            class: App\Shipping\Calculator\DHLCalculator
            arguments: ['@app.dhl_service']
            tags:
                - { name: sylius.shipping_calculator, calculator: dhl, label: "DHL" }

That would be all. This new option ("DHL") will appear on the **ShippingMethod** creation form, in the "calculator" field.

Configurable calculators
------------------------

You can also create configurable calculators, meaning that you can have several **ShippingMethod**'s using same type of calculator, with different settings.

Let's modify the **DHLCalculator**, so that it charges 0 if shipping more than X items.
First step is to create a form type which will be displayed if our calculator is selected.

.. code-block:: php

    <?php
    # src/Form/Type/Shipping/Calculator/DHLConfigurationType.php

    declare(strict_types=1);

    namespace App\Form\Type\Shipping\Calculator;

    use Symfony\Component\Form\AbstractType;
    use Symfony\Component\Form\Extension\Core\Type\IntegerType;
    use Symfony\Component\Form\FormBuilderInterface;
    use Symfony\Component\OptionsResolver\OptionsResolver;
    use Symfony\Component\Validator\Constraints\NotBlank;
    use Symfony\Component\Validator\Constraints\Type;

    final class DHLConfigurationType extends AbstractType
    {
        /**
         * {@inheritdoc}
         */
        public function buildForm(FormBuilderInterface $builder, array $options): void
        {
            $builder
                ->add('limit', IntegerType::class, [
                    'label' => 'Free shipping above total items',
                    'constraints' => [
                        new NotBlank(),
                        new Type(['type' => 'integer']),
                    ]
                ])
            ;
        }

        /**
         * {@inheritdoc}
         */
        public function configureOptions(OptionsResolver $resolver): void
        {
            $resolver
                ->setDefaults([
                    'data_class' => null,
                    'limit' => 10,
                ])
                ->setAllowedTypes('limit', 'integer')
            ;
        }

        /**
         * {@inheritdoc}
         */
        public function getBlockPrefix(): string
        {
            return 'app_shipping_calculator_dhl';
        }
    }

We also need to register the form type in the container and set this form type in the definition of the calculator.

.. code-block:: yaml

    services:
        app.shipping_calculator.dhl:
            class: App\Shipping\Calculator\DHLCalculator
            arguments: ['@app.dhl_service']
            tags:
                - { name: sylius.shipping_calculator, calculator: dhl, form_type: App\Form\Type\Shipping\Calculator\DHLConfigurationType, label: "DHL" }

        app.form.type.shipping_calculator.dhl:
            class: App\Form\Type\Shipping\Calculator\DHLConfigurationType
            tags:
                - { name: form.type }

Perfect, now we're able to use the configuration inside the ``calculate`` method.

.. code-block:: php

    <?php
    # src/Shipping/Calculator/DHLCalculator.php

    declare(strict_types=1);

    namespace App\Shipping\Calculator;

    use Sylius\Component\Shipping\Calculator\CalculatorInterface;
    use Sylius\Component\Shipping\Model\ShipmentInterface;

    final class DHLCalculator implements CalculatorInterface
    {
        /**
         * @var DHLService
         */
        private $dhlService;

        /**
         * @param DHLService $dhlService
         */
        public function __construct(DHLService $dhlService)
        {
            $this->dhlService = $dhlService;
        }

        /**
         * {@inheritdoc}
         */
        public function calculate(ShipmentInterface $subject, array $configuration): int
        {
            if ($subject->getShippingUnitCount() > $configuration['limit']) {
                return 0;
            }

            return $this->dhlService->getShippingCostForWeight($subject->getShippingWeight());
        }

        /**
         * {@inheritdoc}
         */
        public function getType(): string
        {
            return 'dhl';
        }
    }

Your new configurable calculator is ready to use. When you select the "DHL" calculator in **ShippingMethod** form, configuration fields will appear automatically.