Added the LocationGuesser API that guesses a location from a content

src/DependencyInjection/EzSystemsEzPlatformGraphQLExtension.php

@@ -36,6 +36,7 @@ public function load(array $configs, ContainerBuilder $container)
 
         $loader = new Loader\YamlFileLoader($container, new FileLocator(__DIR__ . '/../Resources/config'));
         $loader->load('services/data_loaders.yaml');
+        $loader->load('services/location_guesser.yaml');
         $loader->load('services/mutations.yaml');
         $loader->load('services/resolvers.yaml');
         $loader->load('services/schema.yaml');

src/Exception/MultipleValidLocationsException.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace EzSystems\EzPlatformGraphQL\Exception;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+use eZ\Publish\API\Repository\Values\Content\Location;
+
+class MultipleValidLocationsException extends \Exception
+{
+    /**
+     * @var \eZ\Publish\API\Repository\Values\Content\Location[]
+     */
+    private $locations = [];
+
+    /**
+     * @var \eZ\Publish\API\Repository\Values\Content\Content
+     */
+    private $content;
+
+    /**
+     * @param \eZ\Publish\API\Repository\Values\Content\Content $content
+     * @param \eZ\Publish\API\Repository\Values\Content\Location[] $locations
+     */
+    public function __construct(Content $content, array $locations)
+    {
+        $this->locations = $locations;
+        parent::__construct(
+            sprintf(
+                'Could not determine which location to return for content with id %s. Possible candidates: %s)',
+                $content->id,
+                implode(',', array_map(function (Location $location) { return $location->pathString; }, $locations))
+            )
+        );
+        $this->content = $content;
+    }
+
+    /**
+     * @return Location[]
+     */
+    public function getLocations(): array
+    {
+        return $this->locations;
+    }
+
+    public function getContent(): Content
+    {
+        return $this->content;
+    }
+}

src/Exception/NoValidLocationsException.php

@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace EzSystems\EzPlatformGraphQL\Exception;
+
+use Exception;
+use eZ\Publish\API\Repository\Values\Content\Content;
+
+class NoValidLocationsException extends Exception
+{
+    /**
+     * @var \eZ\Publish\API\Repository\Values\Content\Content|\eZ\Publish\API\Repository\Values\Content\Content[]
+     */
+    private $content;
+
+    /**
+     * NoValidLocationsException constructor.
+     *
+     * @param \eZ\Publish\API\Repository\Values\Content\Content $content
+     */
+    public function __construct(Content $content)
+    {
+        parent::__construct("No valid location could be determined for content #{$content->id}");
+        $this->content = $content;
+    }
+
+    public function getContent(): Content
+    {
+        return $this->content;
+    }
+}

src/GraphQL/Resolver/LocationGuesser/FilterLocationGuesser.php

@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\LocationService;
+use eZ\Publish\API\Repository\Values\Content\Content;
+use eZ\Publish\API\Repository\Values\Content\Location;
+
+/**
+ * Guesses a location based on voters.
+ */
+class FilterLocationGuesser implements LocationGuesser
+{
+    /**
+     * @var \EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser\LocationFilter[]
+     */
+    private $filters;
+
+    /**
+     * @var \eZ\Publish\API\Repository\LocationService
+     */
+    private $locationService;
+
+    /**
+     * @param LocationFilter[] $filters
+     */
+    public function __construct(LocationService $locationService, array $filters)
+    {
+        $this->filters = $filters;
+        $this->locationService = $locationService;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function guessLocation(Content $content): LocationGuess
+    {
+        $locationList = new LocationList($content);
+        foreach ($this->locationService->loadLocations($content->contentInfo) as $location) {
+            $locationList->addLocation($location);
+        }
+
+        foreach ($this->filters as $filter) {
+            $filter->filter($content, $locationList);
+            if ($locationList->hasOneLocation()) {
+                return new LocationGuess($content, $locationList->getLocations());
+            }
+        }
+
+        return new LocationGuess($content, $locationList->getLocations());
+    }
+}

src/GraphQL/Resolver/LocationGuesser/LocationFilter.php

@@ -0,0 +1,20 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+
+interface LocationFilter
+{
+    /**
+     * Given a Content and a LocationList, filters out locations.
+     *
+     * @param \eZ\Publish\API\Repository\Values\Content\Content $content
+     * @param \EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser\LocationList $locationList
+     */
+    public function filter(Content $content, LocationList $locationList): void;
+}

src/GraphQL/Resolver/LocationGuesser/LocationGuess.php

@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+use eZ\Publish\API\Repository\Values\Content\Location;
+use EzSystems\EzPlatformGraphQL\Exception;
+
+class LocationGuess
+{
+    private $content;
+
+    private $locations;
+
+    public function __construct(Content $content, array $locations)
+    {
+        $this->content = $content;
+        $this->locations = $locations;
+    }
+
+    /**
+     * Returns the location guess result if the guess was successful.
+     *
+     * @return \eZ\Publish\API\Repository\Values\Content\Location
+     *
+     * @throws \EzSystems\EzPlatformGraphQL\Exception\MultipleValidLocationsException
+     * @throws \EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser\NoValidLocationsException
+     */
+    public function getLocation(): Location
+    {
+        if (count($this->locations) > 1) {
+            throw new Exception\MultipleValidLocationsException($this->content, $this->locations);
+        } elseif (count($this->locations) === 0) {
+            throw new NoValidLocationsException($this->content);
+        }
+
+        return $this->locations[0];
+    }
+
+    public function isSuccessful(): bool
+    {
+        return count($this->locations) === 1;
+    }
+}

src/GraphQL/Resolver/LocationGuesser/LocationGuesser.php

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+use eZ\Publish\API\Repository\Values\Content\Location;
+
+interface LocationGuesser
+{
+    /**
+     * Tries to guess a valid location for a content item.
+     *
+     * @param \eZ\Publish\API\Repository\Values\Content\Content $content
+     *
+     * @return LocationGuess
+     */
+    public function guessLocation(Content $content): LocationGuess;
+}

src/GraphQL/Resolver/LocationGuesser/LocationList.php

@@ -0,0 +1,76 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+use eZ\Publish\API\Repository\Values\Content\Location;
+use EzSystems\EzPlatformGraphQL\Exception;
+use SplObjectStorage;
+
+/**
+ * The result of the guesser's work.
+ */
+class LocationList
+{
+    /**
+     * The content item locations were guessed for.
+     *
+     * @var \eZ\Publish\API\Repository\Values\Content\Content
+     */
+    private $content;
+
+    /**
+     * @var \SplObjectStorage
+     */
+    private $locations;
+
+    public function __construct(Content $content)
+    {
+        $this->content = $content;
+        $this->locations = new SplObjectStorage();
+    }
+
+    public function addLocation(Location $location)
+    {
+        $this->locations->attach($location);
+    }
+
+    /**
+     * @return \eZ\Publish\API\Repository\Values\Content\Location
+     *
+     * @throws \EzSystems\EzPlatformGraphQL\Exception\MultipleValidLocationsException
+     * @throws \EzSystems\EzPlatformGraphQL\Exception\NoValidLocationsException
+     */
+    public function getLocation(): Location
+    {
+        if (count($this->locations) === 1) {
+            return current($this->locations);
+        } elseif (count($this->locations) > 1) {
+            throw new Exception\MultipleValidLocationsException($this->content, \iterator_to_array($this->locations));
+        } elseif (count($this->locations) === 0) {
+            throw new Exception\NoValidLocationsException($this->content);
+        }
+    }
+
+    public function getLocations(): array
+    {
+        return \iterator_to_array($this->locations);
+    }
+
+    /**
+     * @param \eZ\Publish\API\Repository\Values\Content\Location $location
+     */
+    public function hasOneLocation(): bool
+    {
+        return count($this->locations) === 1;
+    }
+
+    public function filter(Location $location)
+    {
+        $this->locations->detach($location);
+    }
+}

src/GraphQL/Resolver/LocationGuesser/MainLocationFilter.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @copyright Copyright (C) eZ Systems AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace EzSystems\EzPlatformGraphQL\GraphQL\Resolver\LocationGuesser;
+
+use eZ\Publish\API\Repository\Values\Content\Content;
+
+/**
+ * Selects a location, if there are several, by picking the main one if it is part of the current tree root.
+ */
+class MainLocationFilter implements LocationFilter
+{
+    public function filter(Content $content, LocationList $locationList): void
+    {
+        foreach ($locationList->getLocations() as $location) {
+            if ($location->id !== $content->contentInfo->mainLocationId) {
+                $locationList->filter($location);
+            }
+        }
+    }
+}