NewsAggregator.php

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<?php
 
declare(strict_types=1);
 
namespace ILIAS\News\Aggregation;
 
use ILIAS\News\Data\NewsContext;
use SplQueue;
 
class NewsAggregator
{
    protected array $strategies = [];
    protected \ilTree $tree;
 
    public function __construct()
    {
        global $DIC;
 
        $this->tree = $DIC->repositoryTree();
        $this->initializeStrategies();
    }
 
    public function aggregate(array $contexts): array
    {
        $frontier = new SplQueue();
        $result = [];
 
        // Prepare queue
        foreach ($contexts as $context) {
            $frontier->enqueue($context);
        }
 
        while (!$frontier->isEmpty()) {
            $current = $frontier->dequeue();
 
            // Ensure each context is only visited once
            if (array_key_exists($current->getRefId(), $result)) {
                continue;
            }
            $result[$current->getRefId()] = $current;
 
            // Skip if no processing necessary
            $strategy = $this->getStrategy($current->getObjType());
            if ($strategy === null || $strategy->shouldSkip($current)) {
                continue;
            }
 
            $children = $strategy->aggregate($current);
            foreach ($children as $child) {
                if ($strategy->isRecursive()) {
                    // Recursive items will be added directly
                    $result[$child->getRefId()] = $child;
                } else {
                    // Iterative items will be queued for further processing
                    $frontier->enqueue($child);
                }
            }
        }
 
        return array_values($result);
    }
 
    protected function getStrategy(string $object_type): ?NewsAggregationStrategy
    {
        return $this->strategies[$object_type] ?? null;
    }
 
    protected function initializeStrategies(): void
    {
        $subtree_strategy = new SubtreeAggregationStrategy($this->tree);
 
        $this->strategies['cat'] = new CategoryAggregationStrategy($this->tree);
        $this->strategies['crs'] = $subtree_strategy;
        $this->strategies['grp'] = $subtree_strategy;
    }
}