<?php

namespace App\Services;

use App\Models\Client;
use App\Models\User;
use Illuminate\Database\Eloquent\Builder;

class UserHierarchyService
{
    public function visibleUserIds(User $user): array
    {
        if ($user->hasRole('Admin')) {
            return User::query()->pluck('id')->all();
        }

        $visibleIds = [$user->id];
        $frontier = [$user->id];

        while ($frontier !== []) {
            $directReportIds = User::query()
                ->whereIn('manager_id', $frontier)
                ->pluck('id')
                ->all();

            $directReportIds = array_values(array_diff($directReportIds, $visibleIds));

            if ($directReportIds === []) {
                break;
            }

            $visibleIds = array_merge($visibleIds, $directReportIds);
            $frontier = $directReportIds;
        }

        return $visibleIds;
    }

    public function scopeClientsVisibleTo(Builder $query, User $user): Builder
    {
        if ($user->hasRole('Admin')) {
            return $query;
        }

        $visibleUserIds = $this->visibleUserIds($user);

        return $query->whereHas('assignations', function (Builder $query) use ($visibleUserIds) {
            $query->whereIn('user_id', $visibleUserIds);
        });
    }

    public function canViewClient(User $user, Client $client): bool
    {
        if ($user->hasRole('Admin')) {
            return true;
        }

        return $client->assignations()
            ->whereIn('user_id', $this->visibleUserIds($user))
            ->exists();
    }

    public function wouldCreateCycle(User $user, ?int $managerId): bool
    {
        if ($managerId === null) {
            return false;
        }

        if ($user->id === $managerId) {
            return true;
        }

        $frontier = [$user->id];
        $checkedIds = [$user->id];

        while ($frontier !== []) {
            $directReportIds = User::query()
                ->whereIn('manager_id', $frontier)
                ->pluck('id')
                ->all();

            $directReportIds = array_values(array_diff($directReportIds, $checkedIds));

            if (in_array($managerId, $directReportIds, true)) {
                return true;
            }

            $checkedIds = array_merge($checkedIds, $directReportIds);
            $frontier = $directReportIds;
        }

        return false;
    }
}