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

use App\Repository\ZoneRepository;
use App\Repository\ZoneOwnershipException;
use PDO;

final class PdoZoneRepository implements ZoneRepository
{
    public function __construct(private PDO $pdo) {}

    public function find(string $zoneId): ?array
    {
        $st = $this->pdo->prepare(
            'SELECT zone_id, device_id, camera_id, level, polygon_json FROM move_zones WHERE zone_id = ? LIMIT 1'
        );
        $st->execute([$zoneId]);
        $row = $st->fetch();
        return $row === false ? null : $row;
    }

    public function forDevice(string $deviceId): array
    {
        $st = $this->pdo->prepare(
            'SELECT zone_id, device_id, camera_id, level, polygon_json FROM move_zones WHERE device_id = ?'
        );
        $st->execute([$deviceId]);
        return $st->fetchAll();
    }

    public function forCamera(string $cameraId): array
    {
        $st = $this->pdo->prepare(
            'SELECT zone_id, device_id, camera_id, level, polygon_json FROM move_zones WHERE camera_id = ?'
        );
        $st->execute([$cameraId]);
        return $st->fetchAll();
    }

    public function save(array $zone): string
    {
        $zoneId = $zone['zone_id'] ?? null;
        $deviceId = (string)($zone['device_id'] ?? '');
        $cameraId = (string)($zone['camera_id'] ?? '');
        $level = (string)($zone['level'] ?? '');
        $polygonJson = (string)($zone['polygon_json'] ?? '[]');

        if (is_string($zoneId) && $zoneId !== '') {
            return $this->updateOwned($zoneId, $deviceId, $cameraId, $level, $polygonJson);
        }

        $newId = bin2hex(random_bytes(16));
        $st = $this->pdo->prepare(
            'INSERT INTO move_zones (zone_id, device_id, camera_id, level, polygon_json, updated_at)
             VALUES (?, ?, ?, ?, ?, ?)'
        );
        $st->execute([$newId, $deviceId, $cameraId, $level, $polygonJson, time()]);
        return $newId;
    }

    public function delete(string $zoneId): bool
    {
        $st = $this->pdo->prepare('DELETE FROM move_zones WHERE zone_id = ?');
        $st->execute([$zoneId]);
        return $st->rowCount() > 0;
    }

    /**
     * Update path for save(): scoped by (zone_id, device_id, camera_id) so a
     * caller cannot overwrite an unrelated zone by supplying its id with a
     * different device_id/camera_id (closes the cross-tenant overwrite risk
     * flagged in the Task 13 review). Ownership is verified with a SELECT
     * before the UPDATE (rather than trusting UPDATE's rowCount()) because
     * MySQL reports "changed rows", not "matched rows" -- a no-op update
     * (identical level/polygon resubmitted) would otherwise report 0 affected
     * rows and be indistinguishable from an ownership mismatch. The UPDATE's
     * rowCount() is still checked afterwards (0 there is unambiguous, since
     * we already know the row existed a moment ago) to catch the narrow race
     * where the zone is deleted between the ownership check and the UPDATE --
     * without this, save() would return success for a zone that no longer
     * exists.
     */
    private function updateOwned(
        string $zoneId,
        string $deviceId,
        string $cameraId,
        string $level,
        string $polygonJson,
    ): string {
        $owns = $this->pdo->prepare(
            'SELECT 1 FROM move_zones WHERE zone_id = ? AND device_id = ? AND camera_id = ? LIMIT 1'
        );
        $owns->execute([$zoneId, $deviceId, $cameraId]);
        if ($owns->fetchColumn() === false) {
            throw new ZoneOwnershipException('zone not found or not owned by the given device/camera');
        }

        $st = $this->pdo->prepare(
            'UPDATE move_zones SET level = ?, polygon_json = ?, updated_at = ?
              WHERE zone_id = ? AND device_id = ? AND camera_id = ?'
        );
        $st->execute([$level, $polygonJson, time(), $zoneId, $deviceId, $cameraId]);
        if ($st->rowCount() === 0) {
            // Ambiguous on its own: MySQL's rowCount() reports "changed" rows,
            // not "matched" rows, so 0 here could mean either (a) a genuine
            // no-op update (identical level/polygon resubmitted -- not an
            // error) or (b) the zone was deleted between the ownership check
            // above and this UPDATE. Disambiguate with a targeted existence
            // check instead of assuming either case.
            $stillExists = $this->pdo->prepare('SELECT 1 FROM move_zones WHERE zone_id = ? LIMIT 1');
            $stillExists->execute([$zoneId]);
            if ($stillExists->fetchColumn() === false) {
                throw new ZoneOwnershipException('zone was deleted concurrently');
            }
        }
        return $zoneId;
    }
}