// (c) Copyright Ascensio System SIA 2010-2022
//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL its Section 15 shall be amended
// to the effect that Ascensio System SIA expressly excludes the warranty of non-infringement of
// any third-party rights.
//
// This program is distributed WITHOUT ANY WARRANTY, without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
// You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia, EU, LV-1021.
//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
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// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
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// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

namespace ASC.Security.Cryptography;

[Singletone]
public class MachinePseudoKeys
{
    private readonly byte[] _confKey;

    public MachinePseudoKeys(IConfiguration configuration)
    {
        var key = configuration["core:machinekey"];

        if (string.IsNullOrEmpty(key))
        {
            key = configuration["asc:common.machinekey"];
        }

        if (!string.IsNullOrEmpty(key))
        {
            _confKey = Encoding.UTF8.GetBytes(key);
        }
    }


    public byte[] GetMachineConstant()
    {
        if (_confKey != null)
        {
            return _confKey;
        }

        var path = typeof(MachinePseudoKeys).Assembly.Location;
        var fi = new FileInfo(path);

        return BitConverter.GetBytes(fi.CreationTime.ToOADate());
    }

    public byte[] GetMachineConstant(int bytesCount)
    {
        var cnst = Enumerable.Repeat<byte>(0, sizeof(int)).Concat(GetMachineConstant()).ToArray();
        var icnst = BitConverter.ToInt32(cnst, cnst.Length - sizeof(int));
        var rnd = new AscRandom(icnst);
        var buff = new byte[bytesCount];
        rnd.NextBytes(buff);

        return buff;
    }
}