class.ilMDKeywordExposer.php

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<?php

declare(strict_types=1);

use ILIAS\GlobalScreen\Scope\Layout\Provider\AbstractModificationProvider;
use ILIAS\GlobalScreen\ScreenContext\Stack\ContextCollection;
use ILIAS\GlobalScreen\ScreenContext\Stack\CalledContexts;
use ILIAS\GlobalScreen\Scope\Layout\Factory\ContentModification;
use ILIAS\MetaData\Services\ServicesInterface as Metadata;
use ILIAS\MetaData\Services\Reader\ReaderInterface as Reader;

class ilMDKeywordExposer extends AbstractModificationProvider
{
    protected Metadata $md;

    public function __construct(\ILIAS\DI\Container $dic)
    {
        $this->md = $dic->learningObjectMetadata();
        parent::__construct($dic);
    }

    public function isInterestedInContexts(): ContextCollection
    {
        return $this->context_collection->repository();
    }

    public function getContentModification(CalledContexts $screen_context_stack): ?ContentModification
    {
        if ($screen_context_stack->current()->hasReferenceId()) {
            $object_id = $screen_context_stack->current()->getReferenceId()->toObjectId()->toInt();
            $paths = $this->md->paths();
            $reader = $this->generalReader($object_id);

            // Keywords
            $keywords = [];
            foreach ($reader->allData($paths->keywords()) as $keyword) {
                $keywords[] = $keyword->value();
            }
            if (count($keywords) > 0) {
                $this->globalScreen()->layout()->meta()->addMetaDatum(
                    $this->data->htmlMetadata()->userDefined('keywords', implode(',', $keywords))
                );
            }

            // Languages
            $languages = [];
            foreach ($reader->allData($paths->languages()) as $language) {
                $languages[] = $language->value();
            }
            if (count($languages) > 0) {
                $this->globalScreen()->layout()->meta()->addMetaDatum(
                    $this->data->htmlMetadata()->userDefined('languages', implode(',', $languages))
                );
            }

            // Copyright
            if ($this->md->copyrightHelper()->isCopyrightSelectionActive()) {
                $reader = $this->copyrightReader($object_id);
                if ($this->md->copyrightHelper()->hasPresetCopyright($reader)) {
                    $copyright = $this->md->copyrightHelper()->readPresetCopyright($reader)->presentAsString();
                } else {
                    $copyright = $this->md->copyrightHelper()->readCustomCopyright($reader);
                }
                $this->globalScreen()->layout()->meta()->addMetaDatum(
                    $this->data->htmlMetadata()->userDefined('copyright', $copyright)
                );
            }
        }

        return null;
    }

    protected function generalReader(int $object_id): Reader
    {
        $path = $this->md->paths()->custom()->withNextStep('general')->get();
        return $this->md->read(
            $object_id,
            $object_id,
            ilObject::_lookupType($object_id),
            $path
        );
    }

    protected function copyrightReader(int $object_id): Reader
    {
        $path = $this->md->paths()->custom()
                                  ->withNextStep('rights')
                                  ->withNextStep('description')
                                  ->withNextStep('string')
                                  ->get();
        return $this->md->read(
            $object_id,
            $object_id,
            ilObject::_lookupType($object_id),
            $path
        );
    }
}