<?php

namespace MintyPHP\Module\Notifications\Service;

use MintyPHP\Module\Notifications\Repository\NotificationRepositoryInterface;
use MintyPHP\Repository\Tenant\UserTenantRepositoryInterface;

class NotificationService
{
    private const DEDUPE_WINDOW_MINUTES = 30;
    private const DEDUPE_TYPES = [
        'user.created' => true,
        'user.deleted' => true,
        'user.activated' => true,
        'user.deactivated' => true,
        'user.assignment_changed' => true,
    ];

    public function __construct(
        private readonly NotificationRepositoryInterface $notificationRepository,
        private readonly UserTenantRepositoryInterface $userTenantRepository
    ) {
    }

    /** @return list<array<string, mixed>> */
    public function listForUser(int $userId, ?int $tenantId = null, int $limit = 50): array
    {
        if ($userId <= 0) {
            return [];
        }

        return $this->notificationRepository->listByUser($userId, $tenantId, $limit, 0);
    }

    public function unreadCount(int $userId, ?int $tenantId = null): int
    {
        if ($userId <= 0) {
            return 0;
        }

        return $this->notificationRepository->countUnreadByUser($userId, $tenantId);
    }

    public function markAsRead(int $userId, int $notificationId, ?int $tenantId = null): bool
    {
        if ($userId <= 0 || $notificationId <= 0) {
            return false;
        }

        return $this->notificationRepository->markRead($notificationId, $userId, $tenantId);
    }

    public function markAllAsRead(int $userId, ?int $tenantId = null): int
    {
        if ($userId <= 0) {
            return 0;
        }

        return $this->notificationRepository->markAllReadByUser($userId, $tenantId);
    }

    public function dismiss(int $userId, int $notificationId, ?int $tenantId = null): bool
    {
        if ($userId <= 0 || $notificationId <= 0) {
            return false;
        }

        return $this->notificationRepository->delete($notificationId, $userId, $tenantId);
    }

    public function createForUser(
        int $recipientUserId,
        ?int $tenantId,
        string $type,
        string $title,
        ?string $body,
        ?string $link,
        array $data
    ): int|false {
        if ($recipientUserId <= 0 || $type === '' || $title === '') {
            return false;
        }

        $dedupeMeta = $this->buildDedupeMeta($recipientUserId, $tenantId, $type, $data);

        return $this->notificationRepository->create([
            'recipient_user_id' => $recipientUserId,
            'tenant_id' => $tenantId,
            'type' => $type,
            'title' => $title,
            'body' => $body,
            'link' => $link,
            'data' => $data ?: null,
            'dedupe_fingerprint' => $dedupeMeta['fingerprint'] ?? null,
            'dedupe_bucket' => $dedupeMeta['bucket'] ?? null,
        ]);
    }

    /**
     * Fan-out: create notification for all active users in a tenant, optionally excluding actor.
     *
     * @return int Number of notifications created
     */
    public function createForTenantUsers(
        int $tenantId,
        string $type,
        string $title,
        ?string $body,
        ?string $link,
        array $data,
        ?int $excludeUserId
    ): int {
        if ($tenantId <= 0 || $type === '' || $title === '') {
            return 0;
        }

        $userIds = $this->userTenantRepository->listActiveUserIdsByTenantId($tenantId);
        $created = 0;

        foreach ($userIds as $userId) {
            if ($excludeUserId !== null && $userId === $excludeUserId) {
                continue;
            }

            $result = $this->createForUser($userId, $tenantId, $type, $title, $body, $link, $data);
            if ($result !== false) {
                $created++;
            }
        }

        return $created;
    }

    /**
     * Fan-out: create notification only for tenant users whose ID is in $allowedUserIds.
     *
     * @param array<int, mixed> $allowedUserIds Flipped array (user ID as key) for fast lookup
     * @return int Number of notifications created
     */
    public function createForTenantAdminUsers(
        int $tenantId,
        string $type,
        string $title,
        ?string $body,
        ?string $link,
        array $data,
        ?int $excludeUserId,
        array $allowedUserIds
    ): int {
        if ($tenantId <= 0 || $type === '' || $title === '' || $allowedUserIds === []) {
            return 0;
        }

        $userIds = $this->userTenantRepository->listActiveUserIdsByTenantId($tenantId);
        $created = 0;

        foreach ($userIds as $userId) {
            if (!isset($allowedUserIds[$userId])) {
                continue;
            }
            if ($excludeUserId !== null && $userId === $excludeUserId) {
                continue;
            }

            $result = $this->createForUser($userId, $tenantId, $type, $title, $body, $link, $data);
            if ($result !== false) {
                $created++;
            }
        }

        return $created;
    }

    public function purgeOldRead(int $retentionDays = 90): int
    {
        return $this->notificationRepository->purgeReadOlderThanDays($retentionDays);
    }

    public function deleteAllForUser(int $userId): int
    {
        if ($userId <= 0) {
            return 0;
        }

        return $this->notificationRepository->deleteAllByUser($userId);
    }

    /**
     * @param array<string, mixed> $data
     * @return array{fingerprint: string, bucket: int}|array{}
     */
    private function buildDedupeMeta(int $recipientUserId, ?int $tenantId, string $type, array $data): array
    {
        if (!isset(self::DEDUPE_TYPES[$type])) {
            return [];
        }

        $target = $this->dedupeTargetFromData($data);
        if ($target === '') {
            return [];
        }

        $tenantScope = $tenantId !== null && $tenantId > 0 ? $tenantId : 0;
        $raw = implode('|', [
            'recipient:' . $recipientUserId,
            'tenant:' . $tenantScope,
            'type:' . $type,
            'target:' . $target,
        ]);

        return [
            'fingerprint' => hash('sha256', $raw),
            'bucket' => intdiv(time(), self::DEDUPE_WINDOW_MINUTES * 60),
        ];
    }

    /**
     * @param array<string, mixed> $data
     */
    private function dedupeTargetFromData(array $data): string
    {
        $explicit = trim((string) ($data['dedupe_target'] ?? ''));
        if ($explicit !== '') {
            return $explicit;
        }

        $targetUserId = (int) ($data['user_id'] ?? 0);
        if ($targetUserId > 0) {
            return 'user:' . $targetUserId;
        }

        $targetUuid = trim((string) ($data['uuid'] ?? ''));
        if ($targetUuid !== '') {
            return 'uuid:' . $targetUuid;
        }

        return '';
    }

}