aaaaaaaaaaaaaaaa

<?php


function validateEmail($email, &$errors = [],&$fields = [])
{

    if (empty($email)) {
        $errors[] = "Введите эмайл";
        $fields['email']='email';
        return;
    }

    if (!preg_match("/^([a-z,0-9])+@([a-z,0-9])+(.([a-z,0-9])+)+$/", $email)) {
        $errors[] = "Эмайл введен не правильно";
        $fields['email']='email';
    }
    if (strlen($email) < "7") {
        $errors[] = "Эмайл не может быть меньше 7 символов";
        $fields['email']='email';
    }
    if (strlen($email) > "100") {
        $errors[] = "Эмайл не может быть больше 100 символов";
        $fields['email']='email';
    }


}

function validateUsername($username, &$errors = [],&$fields = [])
{
    if (empty($username)) {
        $errors[] = "Введите логин";
        $fields['log']='log';
        return;
    }
    if (!stripslashes($username) && htmlspecialchars($username) && trim($username)) {
        $errors[] = "Логин введён неверно!";
        $fields['log']='log';
    }
    if (strlen($username) < "7") {
        $errors[] = "Логин не может быть короче 7-ми символов";
        $fields['log']='log';
    }
    if (strlen($username) > "100") {
        $errors[] = "Логин длинее 100 символов";
        $fields['log']='log';
    }

    $mysqli = new mysqli("localhost", "root", "", "userlistdb");

    $q = "SELECT * FROM usertbl WHERE username='".$username."'";
    $result = $mysqli->query($q);
    $myrow = $result->fetch_array();
    if($myrow['username'] == $username ){
    $errors[] = 'Юзер с таким именем уже есть';
    $fields['log']='log';

    }


}


function validatePassword($pass, &$errors = [],&$fields = [])
{
    if (empty($pass)) {
        $errors[] = "Введите пароль";
        $fields['pass']='pass';
        return;
    }
    if (!stripslashes($pass) && htmlspecialchars($pass) && trim($pass)) {
        $errors[] = "Пароль введён неверно!";
        $fields['pass']='pass';
    }
    if (strlen($pass) < "7") {
        $errors[] = "Пароль не может быть короче 7-ми символов";
        $fields['pass']='pass';
    }
    if (strlen($pass) > "100") {
        $errors[] = "Пароль длинее 100 символов";
        $fields['pass']='pass';
    }


}


function writeErrors(array $errors)
{
    echo implode("<br>", $errors);
}

//Input
$email = isset($_POST['email']) ? $_POST['email'] : "";
$login = isset($_POST['log']) ? $_POST['log'] : "";
$password = isset($_POST['pass']) ? $_POST['pass'] : "";

function isValidInput($email, $login, $password, array &$errors, array &$fields)
{


    validateEmail($email, $errors,$fields);
    validateUsername($login, $errors,$fields);
    validatePassword($password, $errors,$fields);

    $isValid = count($errors) === 0;


    return $isValid;


}

$errors = [];
$response = [];
$fields = [];

if (isset($_POST['register']) && isValidInput($email, $login, $password, $errors,$fields)) {

    //include_once 'connection.php';
    $mysqli = new mysqli("localhost", "root", "", "userlistdb");
    $password = password_hash($password, PASSWORD_DEFAULT);


    $sql = "INSERT INTO usertbl(
                    username,
                    password,
                    email
                ) VALUES(
                    '$login',
                    '$password',
                    '$email'
                )";
    $result = $mysqli->query($sql) or die(mysql_error());

    $response = [
        'status' => 'OK',
        'messages' => ['Registered successful']
    ];
} else {
    $response = [
        'status' => 'FAILED',
        'messages' => $errors,
        'fields' => $fields
    ];
}


header('Content-Type:application/json;charset=utf-8');
echo json_encode($response);