Extracting Validation

UserController.php

<?php

namespace App\Http\Controllers;

use App\User;
use App\Validators\UserValidator;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
use Illuminate\Http\Request;
use Illuminate\Auth\Access\AuthorizationException;

class UserController
{
    use AuthorizesRequests;

    /**
     * @param Request $request
     */
    public function store(Request $request)
    {
        $this->authorize('add', User::class);

        $data = (new UserValidator())->validate(
            $request->all(),
            $user = new User()
        );

        $user->fill($data)->save();
    }

    /**
     * @param Request $request
     * @param \App\user $user
     */
    public function update(Request $request, User $user)
    {
        $this->authorize('update', $user);

        $data = (new UserValidator())->validate(
            $request->except($request->user()->is_admin ? null : 'is_admin'),
            $user
        );

        $user->fill($data)->save();
    }
}

UserValidator.php

<?php

namespace App\Validators;

use App\User;
use App\Rules\ValidLanguage;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Str;
use Illuminate\Validation\Rule;

class UserValidator
{
    /**
     * @param \App\User $user
     * @return array
     */
    public function rules($user)
    {
        return [
            'name' => [
                $user->exists ? 'sometimes' : null,
                'required',
                'string',
                'max:255'
            ],
            'email' => [
                $user->exists ? 'sometimes' : null,
                'required',
                'string',
                'email',
                'max:255',
                Rule::unique('users', 'email')->ignore($user->exists ? $user->id : null)
            ],
            'business_website' => [
                $user->exists ? 'sometimes' : null,
                'required',
                'domain'
            ],
            'password' => [
                $user->exists ? 'sometimes' : null,
                'required',
                'string',
                'min:8'
            ],
            'language' => ['required']
            'is_admin' => ['bool'],
        ];
    }

    /**
     * @param array $data
     * @param \App\user $user
     * @return array
     */
    public function validate($data, $user)
    {
        return validator($data, $this->rules($user))
                ->after(function ($validator) use ($data, $user) {
                    $this->validateBusinessEmail($validator, $data, $user);
                })
            ->validate();
    }

    /**
     * @param \Illuminate\Contracts\Validation\Validator $validator
     * @param array $data
     * @param \App\User $user
     */
    protected function validateBusinessEmail($validator, $data, $user)
    {
        $email = $data['email'] ?? $user->email;
        $businessWebsite = $data['business_website'] ?? $user->business_website;

        if (! Str::endsWith($email, $businessWebsite)) {
            $validator->errors()->add(
                'email', 'Email is invalid, you must use your business domain'
            );
        }
    }
}