<?php

declare(strict_types=1);

namespace App\Services;

use App\Data\ConnectedApp\ConnectedAppData;
use App\Data\Ui\Dashboard\ServiceAppDto;
use App\Enums\ConnectedAppPermissonEnum;
use App\Helpers\AppPermission;
use App\Models\{ConnectedApp, RestrictedUserPermission, Role, User};
use Carbon\Carbon;
use Illuminate\Support\Collection;

class UserAppAccessService
{
    /**
     * Get all active services for the user as a collection of DTOs.
     *
     * @return Collection<int, ServiceAppDto>
     */
    public function getActiveServices(User $user): Collection
    {
        $user->loadMissing(['roles.apps.protocol', 'roles.apps.provider', 'roles.permissions']);

        $restrictedPermissions = $this->getRestrictedPermissions($user);

        /** @var Collection<int, ServiceAppDto> $appsMap */
        $appsMap = collect();

        /** @var Collection<int, Role> $roles */
        $roles = $user->roles;

        foreach ($roles as $role) {
            /** @var Collection<int, ConnectedApp> $apps */
            $apps = $role->apps;

            foreach ($apps as $app) {
                if ($this->isAppRestrictedForRole($role, $app, $restrictedPermissions)) {
                    continue;
                }

                /** @var mixed $pivot */
                $pivot = $app->pivot;
                $durationStr = (string) $pivot->duration;

                $daysRemaining = $this->getDaysRemainingIfActive($durationStr);

                // If null is returned, the app has expired.
                if (null === $daysRemaining) {
                    continue;
                }

                $this->addOrUpdateAppInMap($appsMap, $app, $durationStr, $daysRemaining);
            }
        }

        return $appsMap->values();
    }

    /**
     * Retrieves a map of restricted permissions for the user, grouped by role ID.
     *
     * * @return array<int, array<int, int>>
     */
    private function getRestrictedPermissions(User $user): array
    {
        return RestrictedUserPermission::query()
            ->where('user_id', $user->id)
            ->get()
            ->groupBy('role_id')
            ->map(fn ($item) => $item->pluck('permission_id')->all())
            ->all();
    }

    /**
     * Checks if the app is restricted for the given role.
     *
     * * @param array<int, array<int, int>> $restrictedPermissions
     */
    private function isAppRestrictedForRole(Role $role, ConnectedApp $app, array $restrictedPermissions): bool
    {
        $permissionName = AppPermission::name(ConnectedAppPermissonEnum::Use, ConnectedAppData::from($app));
        $permission = $role->permissions->firstWhere('name', $permissionName);

        if (! $permission) {
            return false;
        }

        return isset($restrictedPermissions[$role->id])
            && in_array($permission->id, $restrictedPermissions[$role->id], true);
    }

    /**
     * Calculates the days remaining. Returns null if the duration has expired.
     */
    private function getDaysRemainingIfActive(string $durationStr): ?int
    {
        $duration = Carbon::parse($durationStr);
        $now = now();

        if ($duration->isPast()) {
            return null;
        }

        $daysRemaining = (int) $now->diffInDays($duration, false);

        if (0 === $daysRemaining && $now->lt($duration)) {
            return 1;
        }

        return $daysRemaining;
    }

    /**
     * Adds the app to the map or updates it if the new duration is greater than the existing one.
     *
     * * @param Collection<int, ServiceAppDto> $appsMap
     */
    private function addOrUpdateAppInMap(Collection $appsMap, ConnectedApp $app, string $durationStr, int $daysRemaining): void
    {
        /** @var ServiceAppDto|null $existing */
        $existing = $appsMap->get($app->id);
        $duration = Carbon::parse($durationStr);

        $protocolName = $app->protocol?->name ? mb_strtolower($app->protocol->name) : null;
        $providerSlug = $app->provider?->slug ? mb_strtolower($app->provider->slug) : null;

        if (! $existing || Carbon::parse($existing->duration)->lt($duration)) {
            $appsMap->put($app->id, new ServiceAppDto(
                id: $app->id,
                name: $app->name,
                slug: $app->slug,
                duration: $durationStr,
                days_remaining: $daysRemaining,
                is_warning: $daysRemaining <= 3,
                protocol_name: $protocolName,
                provider_slug: $providerSlug,
            ));
        }
    }
}