<?php

declare(strict_types=1);

namespace App\Service;

use App\BpnConnect\Model\ContingentStatus;
use App\Entity\Groups\Accommodation;
use App\Repository\Groups\ContingentDayRepository;
use App\Repository\Groups\ContingentSyncStateRepository;
use Carbon\CarbonImmutable;
use Psr\Log\LoggerInterface;

/**
 * Reads contingent availability out of the local snapshot, and says when it cannot be trusted.
 *
 * Callers get null rather than a silently empty result, because "no data" and "everything is
 * blocked" are indistinguishable once the statuses are flattened — and the two current callers
 * want opposite fallbacks: the API fails loud with a 502, the booking calendar falls back to
 * price coverage alone.
 */
class ContingentSnapshotReader
{
    /**
     * How old the snapshot may get before we stop presenting it as current availability.
     *
     * The near-term sync runs every 15 minutes during the day and hourly overnight, so this only
     * trips when the scheduler is genuinely broken, never on the normal cadence.
     */
    private const string MAX_SNAPSHOT_AGE = '-6 hours';

    public function __construct(
        private readonly ContingentDayRepository $dayRepository,
        private readonly ContingentSyncStateRepository $syncStateRepository,
        private readonly LoggerInterface $logger,
    ) {
    }

    /**
     * Per-day statuses keyed by Y-m-d, or null when there is no usable snapshot for this hotel.
     *
     * Days inside the range that the snapshot does not cover are simply absent from the map;
     * what that means is the caller's decision.
     *
     * @return array<string, ContingentStatus>|null
     */
    public function statusesFor(
        Accommodation $accommodation,
        \DateTimeImmutable $dateFrom,
        \DateTimeImmutable $dateTo,
    ): ?array {
        $hotelCode = $accommodation->getCalendarCode();

        if (null === $hotelCode || '' === $hotelCode) {
            return null;
        }

        if (!$this->isUsable($accommodation, $hotelCode)) {
            return null;
        }

        $statuses = [];

        foreach ($this->dayRepository->findByHotelCodeAndDateRange($hotelCode, $dateFrom, $dateTo) as $date => $day) {
            $statuses[$date] = $day->getStatus();
        }

        return $statuses;
    }

    private function isUsable(Accommodation $accommodation, string $hotelCode): bool
    {
        $syncedAt = $this->syncStateRepository->findOneByAccommodation($accommodation)?->getSyncedAt();

        if (null === $syncedAt) {
            $this->logger->error('No contingent snapshot has been synced yet', ['hotelCode' => $hotelCode]);

            return false;
        }

        if ($syncedAt < CarbonImmutable::now()->modify(self::MAX_SNAPSHOT_AGE)) {
            $this->logger->error('Contingent snapshot is stale', [
                'hotelCode' => $hotelCode,
                'syncedAt' => $syncedAt->format(\DateTimeInterface::ATOM),
            ]);

            return false;
        }

        return true;
    }
}