class Validation
{
    private
    $password,
    $repeatPassword,
    $username,
    $email;

    private static
    $minPassword = 7,
    $confirmPassword,
    $minUsername = 3,
    $maxUsername = 14,
    $validEmail;

    public static function validateEmail($email)
    {
        return (filter_var($email, FILTER_VALIDATE_EMAIL) != self::$validEmail);
    }
    public static function validatePassword($password)
    {
        return(strlen($password) >= self::$minPassword);
    }

    public static function validatecheckbox($agree)
    {
        return(!empty($terms) >= self::$checked);
    }
    public static function validateRepeatPassword($repeatPassword,$password)
    {
            return $repeatPassword === $password;

    }
    public static function validateUsername($username)
    {
            return strlen($username) >= self::$minUsername
            && (strlen($username)) <= self::$maxUsername
            && (filter_var($username ,  FILTER_VALIDATE_REGEXP,["options"=> [ "regexp" => "/^[p{L}0-9s]+$/u"]]) == TRUE);
    }
}

$errors = array();

 $fields = array(
  'username' => array(
    'validator' => 'validateUsername',
    'message'   => 'What is your username?'
  ),
  'email' => array(
    'validator' => 'validateEmail',
    'message'   => 'Please enter a valid email',
  ),
  'password' => array(
    'validator' => 'validatePassword',
    'message'   => 'Password must be a minimum of seven characters'
  )
);

if(!Validation::validateRepeatPassword($password, $repassword))
{
    $errors[] = ["name" => "repassword", "error" => "Passwords must match"];
}
foreach($post as $key => $value)
    {
  if(isset($fields[$key]))
    {
            if(!Validation::{$fields[$key]['validator']}($value))
            {
                $errors[] = ['name' => $key, 'error' => $fields[$key]['message']];
            }
    }
}