/*
 * Copyright (c) 2026 Proton AG
 *
 * This file is part of ProtonVPN.
 *
 * ProtonVPN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ProtonVPN is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ProtonVPN.  If not, see <https://www.gnu.org/licenses/>.
 */

using System.Runtime.InteropServices;
using System.Security;
using System.Text;

namespace ProtonVPN.Client.Logic.Auth.Srp;

public static class SecureStringExtensions
{
    public static unsafe DisposableBytes ToDisposableBytes(this SecureString str)
    {
        IntPtr nativeUnicode = Marshal.SecureStringToGlobalAllocUnicode(str);
        int maxLength = Encoding.UTF8.GetMaxByteCount(str.Length);
        IntPtr nativeUtf8 = Marshal.AllocHGlobal(Encoding.UTF8.GetMaxByteCount(str.Length));
        int nativeUtf8Length = Encoding.UTF8.GetBytes(
            (char*)nativeUnicode.ToPointer(),
            str.Length,
            (byte*)nativeUtf8.ToPointer(),
            maxLength);
        Marshal.ZeroFreeGlobalAllocUnicode(nativeUnicode);

        return new DisposableBytes
        {
            Data = nativeUtf8,
            Length = nativeUtf8Length,
            Capacity = nativeUtf8Length,
        };
    }
}