/*
 * 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.Security;
using Microsoft.Win32;
using ProtonVPN.IssueReporting.Contracts;
using ProtonVPN.Logging.Contracts;
using ProtonVPN.Logging.Contracts.Events.OperatingSystemLogs;

namespace ProtonVPN.Vpn.Wintun;

/**
 * Sometimes ComponentId is missing in the registry and OpenVPN won't find TUN adapter.
 * This class checks if the key is missing and creates one.
 */
public class WintunRegistryFixer : IWintunRegistryFixer
{
    // https://docs.microsoft.com/en-us/windows-hardware/drivers/install/system-defined-device-setup-classes-available-to-vendors
    private readonly string _regPath = "SYSTEM\\ControlSet001\\Control\\Class\\{4d36e972-e325-11ce-bfc1-08002be10318}";
    private readonly ILogger _logger;
    private readonly IIssueReporter _issueReporter;

    public WintunRegistryFixer(ILogger logger, IIssueReporter issueReporter)
    {
        _logger = logger;
        _issueReporter = issueReporter;
    }

    public void EnsureTunAdapterRegistryIsCorrect()
    {
        try
        {
            using RegistryKey? adaptersKey = Registry.LocalMachine.OpenSubKey(_regPath);
            if (adaptersKey == null)
            {
                return;
            }

            string[] folders = adaptersKey.GetSubKeyNames();
            foreach (string folder in folders)
            {
                if (folder.Length != 4)
                {
                    continue;
                }

                using (RegistryKey? adapterKey = Registry.LocalMachine.OpenSubKey($"{_regPath}\\{folder}"))
                {
                    if (adapterKey == null)
                    {
                        continue;
                    }

                    string? matchingDeviceId = adapterKey.GetValue("MatchingDeviceId") as string;
                    if (matchingDeviceId != "wintun")
                    {
                        continue;
                    }

                    string? componentId = adapterKey.GetValue("ComponentId") as string;
                    if (string.IsNullOrEmpty(componentId))
                    {
                        Registry.SetValue($"HKEY_LOCAL_MACHINE\\{_regPath}\\{folder}", "ComponentId", matchingDeviceId);
                        _issueReporter.CaptureMessage("Fixed missing ComponentId on wintun adapter.");
                    }
                    else if (matchingDeviceId != componentId)
                    {
                        _logger.Info<OperatingSystemLog>($"WintunRegistryFixer: ComponentId '{componentId}' " +
                            $"has a value but is different from the MatchingDeviceId '{matchingDeviceId}'.");
                    }
                }
            }
        }
        catch (SecurityException)
        {
        }
    }
}