Validation.php

<?php

declare(strict_types=1);

namespace App\Support\Validation;

abstract class Validation
{
    /**
     * @var array
     */
    private array $data = [];

    /**
     * Define data to be validated.
     *
     * @param array $data
     * @return void
     */
    protected function setData(array $data) : void
    {
        $this->data = $data;
    }

    /**
     * Define all rules that will be used to validate the data.
     *
     * @return array
     */
    abstract protected function rules() : array;

    /**
     * Define messages to validation rules.
     *
     * @return array
     */
    abstract protected function messages() : array;

    /**
     * @throws ValidationException
     */
    public function validate()
    {
        $validation = validator($this->data, $this->rules(), $this->messages());

        if ($validation->fails()) {
            throw new ValidationException($validation->errors());
        }
    }
}

ValidationException.php

<?php

namespace App\Support\Validation;

use Illuminate\Contracts\Support\MessageBag;

class ValidationException extends \Exception
{
    /**
     * @var MessageBag
     */
    private MessageBag $errors;

    public function __construct(MessageBag $messageBag)
    {
        $this->errors = $messageBag;
        parent::__construct($messageBag->first());
    }

    /**
     * @return array
     */
    public function all()
    {
        return $this->errors->all();
    }

    /**
     * @return string
     */
    public function first()
    {
        return $this->errors->first();
    }

    /**
     * @return mixed
     */
    public function last()
    {
        $errors = $this->all();
        return end($errors);
    }

    /**
     * @return string
     */
    public function __toString()
    {
        return $this->first();
    }
}