<?php

namespace MintyPHP\Module\Notifications\Service;

use MintyPHP\Module\Notifications\Repository\NotificationRepositoryInterface;

class NotificationService
{
    public function __construct(
        private readonly NotificationRepositoryInterface $notificationRepository
    ) {
    }

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

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

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

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

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

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

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

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

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

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

    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;
        }

        return $this->notificationRepository->create([
            'recipient_user_id' => $recipientUserId,
            'tenant_id' => $tenantId,
            'type' => $type,
            'title' => $title,
            'body' => $body,
            'link' => $link,
            'data' => $data ?: 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 = $this->listUserIdsForTenant($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 = $this->listUserIdsForTenant($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);
    }

    /**
     * Look up active user IDs belonging to a tenant.
     *
     * @return list<int>
     */
    private function listUserIdsForTenant(int $tenantId): array
    {
        if ($tenantId <= 0) {
            return [];
        }

        $rows = \MintyPHP\DB::select(
            'select ut.user_id from user_tenants ut join users u on u.id = ut.user_id and u.active = 1 where ut.tenant_id = ?',
            (string) $tenantId
        );

        if (!is_array($rows)) {
            return [];
        }

        $ids = [];
        foreach ($rows as $row) {
            $data = $row['user_tenants'] ?? $row;
            if (is_array($data) && isset($data['user_id'])) {
                $ids[] = (int) $data['user_id'];
            }
        }

        return array_values(array_unique($ids));
    }
}