CourseWork/app/Services/LessonService.php

<?php

namespace App\Services;

use App\Models\Grade;
use App\Models\Lesson;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Database\Eloquent\Model;

class LessonService implements ServiceInterface
{

    public function getAll(?Grade $grade = null): Collection
    {
        return $grade->lessons;
    }

    public function getGrades(): Collection
    {
        return Grade::all();
    }

    public function create(array $data): Lesson
    {
        return Lesson::create($data);
    }

    public function update(Model $model, array $data): Lesson
    {
        $model->update($data);

        return $model;
    }

    public function delete($model): void
    {
        $model->delete();
    }
}