<?php
declare(strict_types=1);
namespace App\Repository\Pdo;

use App\Repository\EventRepository;
use PDO;

final class PdoEventRepository implements EventRepository
{
    private const SELECT_COLUMNS =
        'event_id, device_id, camera_id, event_type, severity, track_id, zone_id,
         occurred_at, duration_s, metrics_json, acknowledged_by, acknowledged_at';

    public function __construct(private PDO $pdo) {}

    public function insert(array $event): int
    {
        $st = $this->pdo->prepare(
            'INSERT INTO events
                (device_id, camera_id, event_type, severity, track_id, zone_id,
                 occurred_at, duration_s, metrics_json, received_at)
             VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)'
        );
        $st->execute([
            (string)$event['device_id'],
            (string)$event['camera_id'],
            (string)$event['event_type'],
            (string)$event['severity'],
            $event['track_id'] ?? null,
            $event['zone_id'] ?? null,
            (float)$event['occurred_at'],
            (float)($event['duration_s'] ?? 0.0),
            json_encode($event['metrics'] ?? [], JSON_THROW_ON_ERROR),
            time(),
        ]);
        return (int)$this->pdo->lastInsertId();
    }

    public function recent(int $limit, ?string $severity): array
    {
        if ($severity !== null) {
            $st = $this->pdo->prepare(
                'SELECT ' . self::SELECT_COLUMNS . '
                   FROM events WHERE severity = ?
               ORDER BY occurred_at DESC, event_id DESC LIMIT ?'
            );
            $st->bindValue(1, $severity, PDO::PARAM_STR);
            $st->bindValue(2, $limit, PDO::PARAM_INT);
        } else {
            $st = $this->pdo->prepare(
                'SELECT ' . self::SELECT_COLUMNS . '
                   FROM events
               ORDER BY occurred_at DESC, event_id DESC LIMIT ?'
            );
            $st->bindValue(1, $limit, PDO::PARAM_INT);
        }
        $st->execute();
        return array_map(self::mapRow(...), $st->fetchAll());
    }

    public function find(int $id): ?array
    {
        $st = $this->pdo->prepare('SELECT ' . self::SELECT_COLUMNS . ' FROM events WHERE event_id = ?');
        $st->execute([$id]);
        $row = $st->fetch();
        return $row === false ? null : self::mapRow($row);
    }

    public function acknowledge(int $id, string $user): bool
    {
        // Existence is checked separately (rather than trusting UPDATE's
        // rowCount()) because MySQL's PDO driver, by default, reports
        // "changed rows" rather than "matched rows": re-acknowledging an
        // already-acknowledged event by the same user would otherwise report
        // 0 affected rows and this method would wrongly return false.
        $exists = $this->pdo->prepare('SELECT 1 FROM events WHERE event_id = ? LIMIT 1');
        $exists->execute([$id]);
        if ($exists->fetchColumn() === false) {
            return false;
        }
        $st = $this->pdo->prepare(
            'UPDATE events SET acknowledged_by = ?, acknowledged_at = ? WHERE event_id = ?'
        );
        $st->execute([$user, time(), $id]);
        return true;
    }

    private static function mapRow(array $row): array
    {
        return [
            'event_id' => (int)$row['event_id'],
            'device_id' => $row['device_id'],
            'camera_id' => $row['camera_id'],
            'event_type' => $row['event_type'],
            'severity' => $row['severity'],
            'track_id' => $row['track_id'] !== null ? (int)$row['track_id'] : null,
            'zone_id' => $row['zone_id'],
            'occurred_at' => (float)$row['occurred_at'],
            'duration_s' => (float)$row['duration_s'],
            'metrics' => json_decode((string)($row['metrics_json'] ?? '[]'), true) ?? [],
            'acknowledged_by' => $row['acknowledged_by'],
            'acknowledged_at' => $row['acknowledged_at'] !== null ? (int)$row['acknowledged_at'] : null,
        ];
    }
}