AddressBook - No DB

<?php
$group = array(1 => 'Приятели', 2 => 'Колеги', 3 => 'Познати');

if ($_POST) {
    $name = trim($_POST['name']);
    $phone = trim($_POST['phone']);
    $selectGroup = (int)$_POST['groups'];
    $erros= false;

    if (mb_strlen($name) < 4) {
        echo '<p>Името прекалено кратко!</p>';
        $erros = true;
    }
    if (mb_strlen($phone) < 8 || mb_strlen($phone) > 12) {
        echo '<p>Телефона е неправилен!</p>';
        $erros = true;
    }
    if (!array_key_exists($selectGroup, $group)) {
        echo '<p>Невалидна група</p>';
        $erros = true;
    }
    if(!$erros){
        echo 'Записано!';
    }

}
?>
<header class="bg-primary text-white">
    <div class="container text-center">
        <h1>Добре дошли в Address - Book</h1>
        <p class="lead">Вашето място да запазите контактите си</p>
    </div>
</header>

<section>
    <div class="container text-center">
        <div class="row">
            <div class="col-lg-8 mx-auto">
                <h2>Добавяне на контакти</h2>
                <p class="lead">Всички полета са задължителни</p>
                <form action="" method="post">
                    <div class="form-group">
                        <label for="name">Име</label>
                        <div class="input-group">
                            <div class="input-group-prepend">
                                <div class="input-group-text">
                                    <i class="fa fa-user"></i>
                                </div>
                            </div>
                            <input id="name" name="name" placeholder="Name" type="text" class="form-control" required="required">
                        </div>
                    </div>
                    <div class="form-group">
                        <label for="phone">Телефон</label>
                        <div class="input-group">
                            <div class="input-group-prepend">
                                <div class="input-group-text">
                                    <i class="fa fa-phone"></i>
                                </div>
                            </div>
                            <input id="phone" name="phone" placeholder="Phone" type="text" class="form-control" required="required">
                        </div>
                    </div>
                    <div class="form-group">
                        <label for="email">Емайл адрес</label>
                        <div class="input-group">
                            <div class="input-group-prepend">
                                <div class="input-group-text">
                                    <i class="fa fa-address-card"></i>
                                </div>
                            </div>
                            <input id="email" name="email" placeholder="Email" type="text" class="form-control" required="required">
                        </div>
                    </div>
                    <div class="form-group">
                        <label for="Group">Група</label>
                        <div>
                            <select id="Group" name="'groups"  class="custom-select">
                                <?php
                                foreach ($group as $key => $value) {
                                    echo '<option value="' . $key . '">' . $value . '</option>';
                                }
                                ?>
                            </select>
                        </div>
                    </div>
                    <div class="form-group">
                        <input type="submit" name="add" value="Добави">
                    </div>
                </form>
            </div>
        </div>
    </div>
</section>
<!--
<section class="bg-light">
    <div class="container">
        <div class="row">
            <div class="col-lg-8 mx-auto">
                <h2>Services we offer</h2>
                <p class="lead">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Aut optio velit inventore, expedita quo laboriosam possimus ea consequatur vitae, doloribus consequuntur ex. Nemo assumenda laborum vel, labore ut velit dignissimos.</p>
            </div>
        </div>
    </div>
</section>
-->