/**
     * Create an account in the database.
     * @param $account
     * @return Account|null
     */
    public function create($account)
    {
        $stmt = $this->db->prepare("SELECT count(*) FROM account WHERE username = ?");
        $stmt->bind_param("s", $account->username);
        $stmt->execute();
        $stmt->bind_result($count);
        $stmt->fetch();
        $stmt->close();

        if($count > 0)
            return null;

        if($this->validate($account))
        {
            $stmt = $this->db->prepare("INSERT INTO account(username, password, email, phone, token, reset_time, role) VALUES (?, ?, ?, ?, ?, ?, ?)");
            $hashedPassword = password_hash($account->password, PASSWORD_DEFAULT);
            $stmt->bind_param("sssssis", $account->username, $hashedPassword, $account->email, $account->phone, $account->token, $account->reset_time, $account->role);
            $stmt->execute();
            $stmt->close();
            return new Account($account->username, $hashedPassword, $account->email, $account->phone, $account->token, $account->reset_time, $account->role);
        }
        else
        {
            return null;
        }
    }