Issue #2872190 by bojanz: Create tax rate resolvers

modules/tax/commerce_tax.services.yml

@@ -3,6 +3,16 @@ services:
     class: Drupal\commerce_tax\TaxTypeManager
     parent: default_plugin_manager
 
+  commerce_tax.chain_tax_rate_resolver:
+    class: Drupal\commerce_tax\Resolver\ChainTaxRateResolver
+    tags:
+      - { name: service_collector, call: addResolver, tag: commerce_tax.tax_rate_resolver }
+
+  commerce_tax.default_tax_rate_resolver:
+    class: Drupal\commerce_tax\Resolver\DefaultTaxRateResolver
+    tags:
+      - { name: commerce_tax.tax_rate_resolver, priority: -100 }
+
   commerce_tax.tax_order_processor:
     class: Drupal\commerce_tax\TaxOrderProcessor
     arguments: ['@entity_type.manager']

modules/tax/src/Plugin/Commerce/TaxType/Custom.php

@@ -3,6 +3,7 @@
 namespace Drupal\commerce_tax\Plugin\Commerce\TaxType;
 
 use Drupal\commerce_price\RounderInterface;
+use Drupal\commerce_tax\Resolver\ChainTaxRateResolverInterface;
 use Drupal\commerce_tax\TaxZone;
 use Drupal\Component\Uuid\UuidInterface;
 use Drupal\Component\Utility\Html;
@@ -43,11 +44,13 @@ class Custom extends LocalTaxTypeBase {
    *   The event dispatcher.
    * @param \Drupal\commerce_price\RounderInterface $rounder
    *   The rounder.
+   * @param \Drupal\commerce_tax\ChainTaxRateResolverInterface $chain_rate_resolver
+   *   The chain tax rate resolver.
    * @param \Drupal\Component\Uuid\UuidInterface $uuid_generator
    *   The UUID generator.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EventDispatcherInterface $event_dispatcher, RounderInterface $rounder, UuidInterface $uuid_generator) {
-    parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_type_manager, $event_dispatcher, $rounder);
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EventDispatcherInterface $event_dispatcher, RounderInterface $rounder, ChainTaxRateResolverInterface $chain_rate_resolver, UuidInterface $uuid_generator) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_type_manager, $event_dispatcher, $rounder, $chain_rate_resolver);
 
     $this->uuidGenerator = $uuid_generator;
   }
@@ -63,6 +66,7 @@ public static function create(ContainerInterface $container, array $configuratio
       $container->get('entity_type.manager'),
       $container->get('event_dispatcher'),
       $container->get('commerce_price.rounder'),
+      $container->get('commerce_tax.chain_tax_rate_resolver'),
       $container->get('uuid')
     );
   }

modules/tax/src/Plugin/Commerce/TaxType/LocalTaxTypeBase.php

@@ -9,6 +9,7 @@
 use Drupal\commerce_price\RounderInterface;
 use Drupal\commerce_store\Entity\StoreInterface;
 use Drupal\commerce_tax\TaxZone;
+use Drupal\commerce_tax\Resolver\ChainTaxRateResolverInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\profile\Entity\ProfileInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -26,6 +27,13 @@ abstract class LocalTaxTypeBase extends TaxTypeBase implements LocalTaxTypeInter
    */
   protected $rounder;
 
+  /**
+   * The chain tax rate resolver.
+   *
+   * @var \Drupal\commerce_tax\ChainTaxRateResolverInterface
+   */
+  protected $chainRateResolver;
+
   /**
    * Constructs a new LocalTaxTypeBase object.
    *
@@ -41,11 +49,14 @@ abstract class LocalTaxTypeBase extends TaxTypeBase implements LocalTaxTypeInter
    *   The event dispatcher.
    * @param \Drupal\commerce_price\RounderInterface $rounder
    *   The rounder.
+   * @param \Drupal\commerce_tax\ChainTaxRateResolverInterface $chain_rate_resolver
+   *   The chain tax rate resolver.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EventDispatcherInterface $event_dispatcher, RounderInterface $rounder) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EventDispatcherInterface $event_dispatcher, RounderInterface $rounder, ChainTaxRateResolverInterface $chain_rate_resolver) {
     parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_type_manager, $event_dispatcher);
 
     $this->rounder = $rounder;
+    $this->chainRateResolver = $chain_rate_resolver;
   }
 
   /**
@@ -58,7 +69,8 @@ public static function create(ContainerInterface $container, array $configuratio
       $plugin_definition,
       $container->get('entity_type.manager'),
       $container->get('event_dispatcher'),
-      $container->get('commerce_price.rounder')
+      $container->get('commerce_price.rounder'),
+      $container->get('commerce_tax.chain_tax_rate_resolver')
     );
   }
 
@@ -93,8 +105,8 @@ public function apply(OrderInterface $order) {
 
       $zones = $this->resolveZones($order_item, $customer_profile);
       foreach ($zones as $zone) {
-        $rate = $this->resolveRate($zone, $order_item, $customer_profile);
-        if (!$rate) {
+        $rate = $this->chainRateResolver->resolve($zone, $order_item, $customer_profile);
+        if (!is_object($rate)) {
           // No applicable rate found.
           continue;
         }

modules/tax/src/Resolver/ChainTaxRateResolver.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\commerce_tax\Resolver;
+
+use Drupal\commerce_order\Entity\OrderItemInterface;
+use Drupal\commerce_tax\TaxZone;
+use Drupal\profile\Entity\ProfileInterface;
+
+class ChainTaxRateResolver implements ChainTaxRateResolverInterface {
+
+  /**
+   * The resolvers.
+   *
+   * @var \Drupal\commerce_tax\Resolver\TaxRateResolverInterface[]
+   */
+  protected $resolvers = [];
+
+  /**
+   * Constructs a new ChainTaxRateResolver object.
+   *
+   * @param \Drupal\commerce_tax\Resolver\TaxRateResolverInterface[] $resolvers
+   *   The resolvers.
+   */
+  public function __construct(array $resolvers = []) {
+    $this->resolvers = $resolvers;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addResolver(TaxRateResolverInterface $resolver) {
+    $this->resolvers[] = $resolver;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getResolvers() {
+    return $this->resolvers;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function resolve(TaxZone $zone, OrderItemInterface $order_item, ProfileInterface $customer_profile) {
+    $result = NULL;
+    foreach ($this->resolvers as $resolver) {
+      $result = $resolver->resolve($zone, $order_item, $customer_profile);
+      if ($result) {
+        break;
+      }
+    }
+
+    return $result;
+  }
+
+}

modules/tax/src/Resolver/ChainTaxRateResolverInterface.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Drupal\commerce_tax\Resolver;
+
+/**
+ * Runs the added resolvers one by one until one of them returns the tax rate.
+ *
+ * Each resolver in the chain can be another chain, which is why this interface
+ * extends the tax rate resolver one.
+ */
+interface ChainTaxRateResolverInterface extends TaxRateResolverInterface {
+
+  /**
+   * Adds a resolver.
+   *
+   * @param \Drupal\commerce_tax\Resolver\TaxRateResolverInterface $resolver
+   *   The resolver.
+   */
+  public function addResolver(TaxRateResolverInterface $resolver);
+
+  /**
+   * Gets all added resolvers.
+   *
+   * @return \Drupal\commerce_tax\Resolver\TaxRateResolverInterface[]
+   *   The resolvers.
+   */
+  public function getResolvers();
+
+}

modules/tax/src/Resolver/DefaultTaxRateResolver.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Drupal\commerce_tax\Resolver;
+
+use Drupal\commerce_order\Entity\OrderItemInterface;
+use Drupal\commerce_tax\TaxZone;
+use Drupal\profile\Entity\ProfileInterface;
+
+/**
+ * Returns the tax zone's default tax rate.
+ */
+class DefaultTaxRateResolver implements TaxRateResolverInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function resolve(TaxZone $zone, OrderItemInterface $order_item, ProfileInterface $customer_profile) {
+    $rates = $zone->getRates();
+    // Take the default rate, or fallback to the first rate.
+    $resolved_rate = reset($rates);
+    foreach ($rates as $rate) {
+      if ($rate->isDefault()) {
+        $resolved_rate = $rate;
+        break;
+      }
+    }
+    return $resolved_rate;
+  }
+
+}

modules/tax/src/Resolver/TaxRateResolverInterface.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\commerce_tax\Resolver;
+
+use Drupal\commerce_order\Entity\OrderItemInterface;
+use Drupal\commerce_tax\TaxZone;
+use Drupal\profile\Entity\ProfileInterface;
+
+/**
+ * Defines the interface for tax rate resolvers.
+ */
+interface TaxRateResolverInterface {
+
+  // Stops resolving when there is no applicable tax rate (cause the
+  // provided order item is exempt from sales tax, for example).
+  const NO_APPLICABLE_TAX_RATE = 'no_applicable_tax_rate';
+
+  /**
+   * Resolves the tax rate for the given tax zone.
+   *
+   * @param \Drupal\commerce_tax\TaxZone $zone
+   *   The tax zone.
+   * @param \Drupal\commerce_order\Entity\OrderItemInterface $order_item
+   *   The order item.
+   * @param \Drupal\profile\Entity\ProfileInterface $customer_profile
+   *   The customer profile. Contains the address and tax number.
+   *
+   * @return \Drupal\commerce_tax\TaxRate|string|null
+   *   The tax rate, NO_APPLICABLE_TAX_RATE, or NULL.
+   */
+  public function resolve(TaxZone $zone, OrderItemInterface $order_item, ProfileInterface $customer_profile);
+
+}

modules/tax/src/TaxRate.php

@@ -94,7 +94,7 @@ public function getAmounts() {
   }
 
   /**
-   * Gets the amount valid for the provided date.
+   * Gets the amount valid for the given date.
    *
    * @param \Drupal\Core\Datetime\DrupalDateTime $date
    *   The date.
@@ -106,7 +106,7 @@ public function getAmount(DrupalDateTime $date = NULL) {
     // Default to the current date.
     $date = $date ?: new DrupalDateTime();
     // Amount start/end dates don't include the time, so discard the time
-    // portion of the provided date to make the matching precise.
+    // portion of the given date to make the matching precise.
     $date->setTime(0, 0);
     foreach ($this->amounts as $amount) {
       $start_date = $amount->getStartDate();

modules/tax/src/TaxZone.php

@@ -109,7 +109,7 @@ public function getRates() {
   }
 
   /**
-   * Checks whether the provided address belongs to the zone.
+   * Checks whether the given address belongs to the zone.
    *
    * @param \CommerceGuys\Addressing\AddressInterface $address
    *   The address.