RatingsDistribution.php

<?php

namespace App\Api\Statistics\Helper;

use Doctrine\ORM\EntityManagerInterface;
use Doctrine\ORM\QueryBuilder;
use App\Api\Rating\Rating;
use App\Api\Rating\Repository\RatingRepository;
use Psr\Cache\CacheItemPoolInterface;

class RatingsDistribution
{
    private const EMPTY_DISTRIBUTION = [
        1 => 0, 2 => 0, 3 => 0, 4 => 0, 5 => 0,
        6 => 0, 7 => 0, 8 => 0, 9 => 0, 10 => 0,
    ];
    private const CACHE_KEY = 'ratings_distribution_%s';
    private const CACHE_TTL = 60 * 10; // 10 min cache TTL

    private ?QueryBuilder $baseBuilder = null;

    public function __construct(
        private RatingRepository $ratingRepository,
        private CacheItemPoolInterface $cacheApp,
    ) {
    }

    public function getCached(string $bookId): array
    {
        $cacheItem = $this->cacheApp->getItem(sprintf(self::CACHE_KEY, $bookId));
        if (!$cacheItem->isHit()) {
            $cacheItem->set($this->get($bookId));
            $cacheItem->expiresAfter(self::CACHE_TTL);
            $this->cacheApp->save($cacheItem);
        }

        return $cacheItem->get();
    }

    private function get(string $bookId): array
    {
        $distribution = $this->makeQueryForBook($bookId);
        if (null === $distribution) {
            return self::EMPTY_DISTRIBUTION;
        }

        $localDistribution = self::EMPTY_DISTRIBUTION;
        foreach ($distribution as $result) {
            $localDistribution[$result['rating']] = $result['count'];
        }

        return $localDistribution;
    }

    private function makeQueryForBook(string $bookId): ?array
    {
        if (null === $this->baseBuilder) {
            $this->baseBuilder = $this
                ->ratingRepository
                ->createQueryBuilder('r')
                ->select('r.rating, COUNT(r.id) as count')
                ->andWhere('r.book = :bookId')
                ->groupBy('r.rating');
        }

        return (clone $this->baseBuilder)
            ->setParameter('bookId', $bookId)
            ->getQuery()
            ->getResult();
    }
}