<?php

declare(strict_types=1);

class RatingManager
{
    public function __construct(private PDO $pdo)
    {
    }

    public function rate(string $uuid, string $email, int $rating): void
    {
        $st = $this->pdo->prepare(
            'INSERT INTO article_ratings (article_uuid, user_email, rating)
             VALUES (:uuid, :email, :r)
             ON CONFLICT (article_uuid, user_email)
             DO UPDATE SET rating = :r, rated_at = NOW()'
        );
        $st->execute([':uuid' => $uuid, ':email' => strtolower($email), ':r' => $rating]);
    }

    /** @return array{avg: float|null, count: int} */
    public function statsForArticle(string $uuid): array
    {
        $st = $this->pdo->prepare(
            'SELECT ROUND(AVG(rating)::numeric, 1) as avg, COUNT(*) as count
             FROM article_ratings WHERE article_uuid = :uuid'
        );
        $st->execute([':uuid' => $uuid]);
        $row = $st->fetch(PDO::FETCH_ASSOC);
        return [
            'avg'   => $row && $row['avg'] !== null ? (float)$row['avg'] : null,
            'count' => $row ? (int)$row['count'] : 0,
        ];
    }

    public function userRating(string $uuid, string $email): ?int
    {
        $st = $this->pdo->prepare(
            'SELECT rating FROM article_ratings WHERE article_uuid = :uuid AND user_email = :email'
        );
        $st->execute([':uuid' => $uuid, ':email' => strtolower($email)]);
        $v = $st->fetchColumn();
        return $v !== false ? (int)$v : null;
    }
}