Importer.php

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<?php

declare(strict_types=1);

namespace ILIAS\MetaData\Settings\Vocabularies\Import;

use ILIAS\MetaData\Vocabularies\Controlled\CreationRepositoryInterface as ControlledVocabsRepository;
use ILIAS\MetaData\Paths\PathInterface;
use ILIAS\MetaData\Paths\FactoryInterface as PathFactory;
use ILIAS\MetaData\Vocabularies\Slots\Identifier as SlotIdentifier;
use ILIAS\MetaData\Vocabularies\Slots\HandlerInterface as SlotHandler;

class Importer
{
    protected const PATH_TO_SCHEMA = __DIR__ . '/../../../../VocabValidation/controlled_vocabulary.xsd';

    protected PathFactory $path_factory;
    protected ControlledVocabsRepository $vocab_repo;
    protected SlotHandler $slot_handler;

    public function __construct(
        PathFactory $path_factory,
        ControlledVocabsRepository $vocab_repo,
        SlotHandler $slot_handler
    ) {
        $this->path_factory = $path_factory;
        $this->vocab_repo = $vocab_repo;
        $this->slot_handler = $slot_handler;
    }

    public function import(string $xml_string): Result
    {
        $errors_or_xml = $this->loadXML($xml_string);
        if (is_array($errors_or_xml)) {
            return new Result(...$errors_or_xml);
        }
        $xml_path = new \DOMXPath($errors_or_xml);
        $errors = [];

        try {
            $slot = $this->extractVocabularySlot($xml_path);
        } catch (\ilMDPathException $e) {
            $errors[] = $e->getMessage();
        }
        if (isset($slot) && $slot === SlotIdentifier::NULL) {
            $errors[] = 'Cannot add vocabulary, invalid element or condition.';
        }

        $duplicates = $this->findDuplicateValues($xml_path);
        if (!empty($duplicates)) {
            $errors[] = 'The following values are not unique: ' . implode(', ', $duplicates);
        }
        if (empty($errors) && isset($slot)) {
            $already_exist = $this->findAlreadyExistingValues($xml_path, $slot);
            if (!empty($already_exist)) {
                $errors[] = 'The following values already exist in other vocabularies of the element: ' .
                    implode(', ', $already_exist);
            }
        }

        if (empty($errors) && isset($slot)) {
            try {
                $vocab_id = $this->createVocabulary(
                    $slot,
                    $this->extractSource($xml_path)
                );
            } catch (\ilMDVocabulariesException $e) {
                $errors[] = $e->getMessage();
            }
        }
        if (empty($errors) && isset($vocab_id)) {
            $this->addValuesToVocabulary($xml_path, $vocab_id);
        }

        return new Result(...$errors);
    }

    protected function loadXML(string $xml_string): \DOMDocument|array
    {
        $use_internal_errors = libxml_use_internal_errors(true);

        $xml = new \DOMDocument('1.0', 'utf-8');
        $xml->loadXML($xml_string);

        if (!$xml->schemaValidate(self::PATH_TO_SCHEMA)) {
            $errors = [];
            foreach (libxml_get_errors() as $error) {
                $errors[] = $error->message;
            }
        }

        libxml_clear_errors();
        libxml_use_internal_errors($use_internal_errors);

        return empty($errors) ? $xml : $errors;
    }

    protected function extractPathToElement(\DOMXPath $xml_path): PathInterface
    {
        $node = $xml_path->query('//vocabulary/appliesTo/pathToElement')->item(0);
        return $this->writeToPath($node);
    }

    protected function extractPathToCondition(\DOMXPath $xml_path): ?PathInterface
    {
        $node = $xml_path->query('//vocabulary/appliesTo/condition/pathToElement')->item(0);
        return is_null($node) ? null : $this->writeToPath($node, true);
    }

    protected function extractConditionValue(\DOMXPath $xml_path): ?string
    {
        $node = $xml_path->query('//vocabulary/appliesTo/condition/@value')->item(0);
        return $node?->nodeValue;
    }

    protected function extractVocabularySlot(\DOMXPath $xml_path): SlotIdentifier
    {
        $path_to_element = $this->extractPathToElement($xml_path);
        $path_to_condition = $this->extractPathToCondition($xml_path);
        $condition_value = $this->extractConditionValue($xml_path);

        return $this->slot_handler->identiferFromPathAndCondition(
            $path_to_element,
            $path_to_condition,
            $condition_value
        );
    }

    protected function extractSource(\DOMXPath $xml_path): string
    {
        $node = $xml_path->query('//vocabulary/source')->item(0);
        return (string) $node?->nodeValue;
    }

    protected function extractValuesAndLabels(\DOMXPath $xml_path): \Generator
    {
        $nodes = $xml_path->query('//vocabulary/values/value');
        foreach ($nodes as $node) {
            $label = $node->hasAttribute('label') ? $node->getAttribute('label') : '';
            $value = $node->nodeValue;
            yield $value => $label;
        }
    }

    protected function findDuplicateValues(\DOMXPath $xml_path): array
    {
        $values = [];
        $duplicates = [];
        foreach ($this->extractValuesAndLabels($xml_path) as $value => $label) {
            if (in_array($value, $values) && !in_array($value, $duplicates)) {
                $duplicates[] = $value;
            }
            $values[] = $value;
        }

        return $duplicates;
    }

    protected function findAlreadyExistingValues(
        \DOMXPath $xml_path,
        SlotIdentifier $slot
    ): array {
        $values = [];
        foreach ($this->extractValuesAndLabels($xml_path) as $value => $label) {
            $values[] = $value;
        }
        return iterator_to_array($this->vocab_repo->findAlreadyExistingValues(
            $slot,
            ...$values
        ));
    }

    protected function createVocabulary(
        SlotIdentifier $slot,
        string $source
    ): string {
        return $this->vocab_repo->create($slot, $source);
    }

    protected function addValuesToVocabulary(
        \DOMXPath $xml_path,
        string $vocab_id
    ): void {
        foreach ($this->extractValuesAndLabels($xml_path) as $value => $label) {
            $this->vocab_repo->addValueToVocabulary(
                $vocab_id,
                $value,
                $label
            );
        }
    }

    protected function writeToPath(\DOMElement $path_in_xml, bool $relative = false): PathInterface
    {
        $builder = $this->path_factory->custom();
        foreach ($path_in_xml->childNodes as $step) {
            if (!($step instanceof \DOMElement)) {
                continue;
            }
            if ($step->nodeName === 'step') {
                $builder = $builder->withNextStep($step->nodeValue);
            } elseif ($step->nodeName === 'stepToSuper') {
                $builder = $builder->withNextStepToSuperElement();
            }
        }
        return $builder->withRelative($relative)->get();
    }
}