using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Security;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Win32.SafeHandles;
using TrustedUninstaller.Shared.Actions;

namespace TrustedUninstaller.Shared
{
    public class ProcessPrivilege
    {
        private static Win32.TokensEx.SafeTokenHandle userToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
        private static Win32.TokensEx.SafeTokenHandle elevatedUserToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
        private static Win32.TokensEx.SafeTokenHandle systemToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
        private static Win32.TokensEx.SafeTokenHandle impsersonatedSystemToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
        private static Win32.TokensEx.SafeTokenHandle lsassToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);

        internal static void ResetTokens()
        {
            elevatedUserToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
            lsassToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
            systemToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
            impsersonatedSystemToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
            userToken = new Win32.TokensEx.SafeTokenHandle(IntPtr.Zero);
        }
        
        public static void StartPrivilegedTask(AugmentedProcess.Process process, Privilege privilege)
        {
            var tcs = StartThread(process, privilege);
            tcs.Task.Wait();
            for (int i = 0; tcs.Task.Result != null && i <= 3; i++)
            {
                ErrorLogger.WriteToErrorLog("Error launching privileged process: " + tcs.Task.Result.Message, tcs.Task.Result.StackTrace, "PrivilegedProcess Warning",
                    Path.GetFileName(process.StartInfo.FileName));
                ResetTokens();
                Thread.Sleep(500 * i);
                tcs = StartThread(process, privilege);
                tcs.Task.Wait();
            }

            if (tcs.Task.Result != null)
                throw new SecurityException("Error launching privileged process.", tcs.Task.Result);
        }

        private static TaskCompletionSource<Exception> StartThread(AugmentedProcess.Process process, Privilege privilege)
        {
            var tcs = new TaskCompletionSource<Exception>();
            var thread = new Thread(() =>
            {
                try
                {
                    switch (privilege)
                    {
                        case (Privilege.System):
                            GetSystemToken();
                            process.Start(AugmentedProcess.Process.CreateType.RawToken, ref systemToken);
                            break;
                        case (Privilege.CurrentUser):
                            GetUserToken(true);
                            process.Start(AugmentedProcess.Process.CreateType.UserToken, ref userToken);
                            break;
                        case (Privilege.CurrentUserElevated):
                            GetElevatedUserToken();
                            process.Start(AugmentedProcess.Process.CreateType.RawToken, ref elevatedUserToken);
                            break;
                        default:
                            throw new ArgumentException("Unexpected.");
                    }
                }
                catch (Exception e)
                {
                    tcs.SetResult(e);
                    return;
                }

                tcs.SetResult(null);
            });
            thread.Start();
            return tcs;
        }

        private static uint GetUserSession()
        {
            var sessionId = Win32.WTS.WTSGetActiveConsoleSessionId();
            if (sessionId != 0xFFFFFFFF) return sessionId;
            IntPtr pSessionInfo = IntPtr.Zero;
            Int32 count = 0;
            if (Win32.WTS.WTSEnumerateSessions((IntPtr)null, 0, 1, ref pSessionInfo, ref count) == 0)
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Error enumerating user sessions.");
            Int32 dataSize = Marshal.SizeOf(typeof(Win32.WTS.WTS_SESSION_INFO));
            Int64 current = (Int64)pSessionInfo;
            for (int i = 0; i < count; i++)
            {
                Win32.WTS.WTS_SESSION_INFO si =
                    (Win32.WTS.WTS_SESSION_INFO)Marshal.PtrToStructure((System.IntPtr)current,
                        typeof(Win32.WTS.WTS_SESSION_INFO));
                current += dataSize;
                if (si.State == Win32.WTS.WTS_CONNECTSTATE_CLASS.WTSActive)
                {
                    sessionId = (uint)si.SessionID;
                    break;
                }
            }
            Win32.WTS.WTSFreeMemory(pSessionInfo);
            return sessionId;
        }

        private static void GetUserToken(bool getPrivileges)
        {
            if (getPrivileges)
            {
                GetSystemToken();
                var result = Win32.Tokens.ImpersonateLoggedOnUser(systemToken);
                if (!result)
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Error impersonating system process token.");
                
                Win32.TokensEx.AdjustCurrentPrivilege(Win32.Tokens.SE_ASSIGNPRIMARYTOKEN_NAME);
                Win32.TokensEx.AdjustCurrentPrivilege(Win32.Tokens.SE_INCREASE_QUOTA_NAME);
            }
            
            if (userToken.DangerousGetHandle() != IntPtr.Zero)
                return;
            
            var sessionId = GetUserSession();

            if (Win32.WTS.WTSQueryUserToken(sessionId, out Win32.TokensEx.SafeTokenHandle wtsToken))
            {
                if (!Win32.Tokens.DuplicateTokenEx(wtsToken, Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS,
                        IntPtr.Zero,
                        Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                        Win32.Tokens.TOKEN_TYPE.TokenPrimary, out userToken))
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error(),
                        "Failed to duplicate process token for lsass.");
                }
                return;
            }
            throw new Win32Exception(Marshal.GetLastWin32Error(), "Error fetching active user session token.");
        }

        private static void GetElevatedUserToken()
        {
            GetSystemToken();
            var result = Win32.Tokens.ImpersonateLoggedOnUser(systemToken);

            if (!result)
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Error impersonating system process token.");
            
            if (lsassToken.DangerousGetHandle() == IntPtr.Zero)
            {
                var processHandle = Win32.Process.OpenProcess(Win32.Process.ProcessAccessFlags.QueryLimitedInformation, false, Process.GetProcessesByName("lsass").First().Id);
                if (!Win32.Tokens.OpenProcessToken(processHandle,
                        Win32.Tokens.TokenAccessFlags.TOKEN_DUPLICATE |
                        Win32.Tokens.TokenAccessFlags.TOKEN_ASSIGN_PRIMARY |
                        Win32.Tokens.TokenAccessFlags.TOKEN_QUERY | Win32.Tokens.TokenAccessFlags.TOKEN_IMPERSONATE,
                        out var tokenHandle))
                {
                    Win32.CloseHandle(processHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to open process token for lsass.");
                }

                if (!Win32.Tokens.DuplicateTokenEx(tokenHandle, Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS,
                        IntPtr.Zero,
                        Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation,
                        Win32.Tokens.TOKEN_TYPE.TokenImpersonation, out lsassToken))
                {
                    Win32.CloseHandle(processHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(),
                        "Failed to duplicate process token for lsass.");
                }

                Win32.CloseHandle(processHandle);
            }

            
            result = Win32.Tokens.ImpersonateLoggedOnUser(lsassToken);
            if (!result)
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Error impersonating lsass process token.");
            
            
            Win32.TokensEx.AdjustCurrentPrivilege(Win32.Tokens.SE_ASSIGNPRIMARYTOKEN_NAME);
            Win32.TokensEx.AdjustCurrentPrivilege(Win32.Tokens.SE_INCREASE_QUOTA_NAME);
            
            
            if (elevatedUserToken.DangerousGetHandle() != IntPtr.Zero)
                return;
            
            
            var privileges = new[]
            {
                Win32.Tokens.SE_INCREASE_QUOTA_NAME,
                Win32.Tokens.SE_MACHINE_ACCOUNT_NAME, Win32.Tokens.SE_SECURITY_NAME,
                Win32.Tokens.SE_TAKE_OWNERSHIP_NAME, Win32.Tokens.SE_LOAD_DRIVER_NAME,
                Win32.Tokens.SE_SYSTEM_PROFILE_NAME, Win32.Tokens.SE_SYSTEMTIME_NAME,
                Win32.Tokens.SE_PROFILE_SINGLE_PROCESS_NAME, Win32.Tokens.SE_INCREASE_BASE_PRIORITY_NAME,
                Win32.Tokens.SE_CREATE_PERMANENT_NAME,
                Win32.Tokens.SE_BACKUP_NAME, Win32.Tokens.SE_RESTORE_NAME, Win32.Tokens.SE_SHUTDOWN_NAME,
                Win32.Tokens.SE_DEBUG_NAME, Win32.Tokens.SE_AUDIT_NAME, Win32.Tokens.SE_SYSTEM_ENVIRONMENT_NAME,
                Win32.Tokens.SE_CHANGE_NOTIFY_NAME,
                Win32.Tokens.SE_UNDOCK_NAME, Win32.Tokens.SE_SYNC_AGENT_NAME,
                Win32.Tokens.SE_ENABLE_DELEGATION_NAME, Win32.Tokens.SE_MANAGE_VOLUME_NAME,
                Win32.Tokens.SE_IMPERSONATE_NAME, Win32.Tokens.SE_CREATE_GLOBAL_NAME,
                Win32.Tokens.SE_TRUSTED_CREDMAN_ACCESS_NAME, Win32.Tokens.SE_RELABEL_NAME,
                Win32.Tokens.SE_TIME_ZONE_NAME,
                Win32.Tokens.SE_CREATE_SYMBOLIC_LINK_NAME, Win32.Tokens.SE_DELEGATE_SESSION_USER_IMPERSONATE_NAME
            };
            var authId = Win32.Tokens.SYSTEM_LUID;
            
            GetUserToken(false);

            Win32.Tokens.DuplicateTokenEx(userToken,
                Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS, IntPtr.Zero,
                Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification, Win32.Tokens.TOKEN_TYPE.TokenPrimary,
                out Win32.TokensEx.SafeTokenHandle dupedUserToken);
 
            Win32.SID.AllocateAndInitializeSid(
                ref Win32.SID.SECURITY_MANDATORY_LABEL_AUTHORITY,
                1,
                (int)Win32.SID.SECURITY_MANDATORY_LABEL.High,
                0,
                0,
                0,
                0,
                0,
                0,
                0,
                out IntPtr integritySid);
            
            var tokenMandatoryLabel = new Win32.Tokens.TOKEN_MANDATORY_LABEL() {
                Label = default(Win32.SID.SID_AND_ATTRIBUTES)
            };

            tokenMandatoryLabel.Label.Attributes = (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_INTEGRITY;
            tokenMandatoryLabel.Label.Sid        = integritySid;

            var integritySize = Marshal.SizeOf(tokenMandatoryLabel);
            var tokenInfo = Marshal.AllocHGlobal(integritySize);

            Marshal.StructureToPtr(tokenMandatoryLabel, tokenInfo, false);
            
            Win32.Tokens.SetTokenInformation(
                dupedUserToken,
                Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenIntegrityLevel,
                tokenInfo,
                integritySize + Win32.SID.GetLengthSid(integritySid));
            
            
            var pTokenUser = Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenUser);
            var pTokenOwner =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenOwner);
            var pTokenPrivileges =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenPrivileges);
            var pTokenGroups =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenGroups);
            var pTokenPrimaryGroup =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenPrimaryGroup);
            var pTokenDefaultDacl =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenDefaultDacl);
            var pTokenSource =
                Win32.TokensEx.GetInfoFromToken(dupedUserToken, Win32.Tokens.TOKEN_INFORMATION_CLASS.TokenSource);
            
            var tokenUser =
                (Win32.Tokens.TOKEN_USER)Marshal.PtrToStructure(pTokenUser, typeof(Win32.Tokens.TOKEN_USER));
            if (!Win32.TokensEx.CreateTokenPrivileges(privileges, out var tokenPrivileges))
                tokenPrivileges =
                    (Win32.Tokens.TOKEN_PRIVILEGES)Marshal.PtrToStructure(pTokenPrivileges,
                        typeof(Win32.Tokens.TOKEN_PRIVILEGES));
            var tokenGroups = (Win32.Tokens.TOKEN_GROUPS)Marshal.PtrToStructure(
                pTokenGroups, typeof(Win32.Tokens.TOKEN_GROUPS));
            var tokenOwner =
                (Win32.Tokens.TOKEN_OWNER)Marshal.PtrToStructure(pTokenOwner, typeof(Win32.Tokens.TOKEN_OWNER));
            var tokenPrimaryGroup =
                (Win32.Tokens.TOKEN_PRIMARY_GROUP)Marshal.PtrToStructure(pTokenPrimaryGroup,
                    typeof(Win32.Tokens.TOKEN_PRIMARY_GROUP));
            var tokenDefaultDacl = (Win32.Tokens.TOKEN_DEFAULT_DACL)Marshal.PtrToStructure(
                pTokenDefaultDacl, typeof(Win32.Tokens.TOKEN_DEFAULT_DACL));
            var tokenSource = (Win32.Tokens.TOKEN_SOURCE)Marshal.PtrToStructure(
                pTokenSource, typeof(Win32.Tokens.TOKEN_SOURCE));
            /*
            for (var idx = 0; idx < tokenPrivileges.PrivilegeCount - 1; idx++)
            {
                if ((tokenPrivileges.Privileges[idx].Attributes &
                     (uint)Win32.Tokens.SE_PRIVILEGE_ATTRIBUTES.SE_PRIVILEGE_ENABLED) != 0)
                {
                }

                if ((tokenPrivileges.Privileges[idx].Attributes &
                     (uint)Win32.Tokens.SE_PRIVILEGE_ATTRIBUTES.SE_PRIVILEGE_ENABLED_BY_DEFAULT) != 0)
                {
                }
            }
            */
            
            IntPtr adminsSid = IntPtr.Zero;
            IntPtr localAndAdminSid = IntPtr.Zero;

            bool adminsFound = false;
            bool localAndAdminFound = false;

            for (var idx = 0; idx < tokenGroups.GroupCount - 1; idx++)
            {
                Win32.SID.ConvertSidToStringSid(tokenGroups.Groups[idx].Sid, out string strSid);
                if (string.Compare(strSid, Win32.SID.DOMAIN_ALIAS_RID_ADMINS, StringComparison.OrdinalIgnoreCase) == 0)
                {
                    adminsFound = true;
                    tokenGroups.Groups[idx].Attributes = (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED |
                                                         (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES
                                                             .SE_GROUP_ENABLED_BY_DEFAULT | (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_MANDATORY | (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_OWNER;
                } else if (string.Compare(strSid, Win32.SID.DOMAIN_ALIAS_RID_LOCAL_AND_ADMIN_GROUP, StringComparison.OrdinalIgnoreCase) == 0)
                {
                    localAndAdminFound = true;
                    tokenGroups.Groups[idx].Attributes = (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED |
                                                         (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES
                                                             .SE_GROUP_ENABLED_BY_DEFAULT | (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_MANDATORY;
                }
            }
            
            if (!adminsFound)
            {
                Win32.SID.ConvertStringSidToSid(Win32.SID.DOMAIN_ALIAS_RID_ADMINS, out adminsSid);
                tokenGroups.Groups[tokenGroups.GroupCount].Sid = adminsSid;
                tokenGroups.Groups[tokenGroups.GroupCount].Attributes =
                    (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED |
                    (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED_BY_DEFAULT;
                tokenGroups.GroupCount++;
            }
            if (!localAndAdminFound)
            {
                Win32.SID.ConvertStringSidToSid(Win32.SID.DOMAIN_ALIAS_RID_LOCAL_AND_ADMIN_GROUP, out localAndAdminSid);
                tokenGroups.Groups[tokenGroups.GroupCount].Sid = localAndAdminSid;
                tokenGroups.Groups[tokenGroups.GroupCount].Attributes =
                    (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED |
                    (uint)Win32.Tokens.SE_GROUP_ATTRIBUTES.SE_GROUP_ENABLED_BY_DEFAULT;
                tokenGroups.GroupCount++;
            }
            
            var expirationTime = new Win32.LARGE_INTEGER() { QuadPart = -1L };
            var sqos = new Win32.Tokens.SECURITY_QUALITY_OF_SERVICE(
                Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification, Win32.Tokens.SECURITY_STATIC_TRACKING,
                0);
            var oa = new Win32.Tokens.OBJECT_ATTRIBUTES(string.Empty, 0) { };
            var pSqos = Marshal.AllocHGlobal(Marshal.SizeOf(sqos));
            Marshal.StructureToPtr(sqos, pSqos, true);
            oa.SecurityQualityOfService = pSqos;
            
            var status = Win32.Tokens.ZwCreateToken(out elevatedUserToken,
                Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS, ref oa,  Win32.Tokens.TOKEN_TYPE.TokenPrimary,
                ref authId, ref expirationTime, ref tokenUser, ref tokenGroups, ref tokenPrivileges, ref tokenOwner,
                ref tokenPrimaryGroup, ref tokenDefaultDacl, ref tokenSource);
            
            Win32.LocalFree(pTokenUser);
            Win32.LocalFree(pTokenOwner);
            Win32.LocalFree(pTokenGroups);
            Win32.LocalFree(pTokenDefaultDacl);
            Win32.LocalFree(pTokenPrivileges);
            Win32.LocalFree(pTokenPrimaryGroup);

            if (adminsSid != IntPtr.Zero)
                Win32.SID.FreeSid(adminsSid);
            if (localAndAdminSid != IntPtr.Zero)
                Win32.SID.FreeSid(localAndAdminSid);
            if (integritySid != IntPtr.Zero)
                Win32.SID.FreeSid(integritySid);
            
            if (status != 0)
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Error creating elevated user token: " + status);
        }

        public static void GetSystemToken()
        {
            if (systemToken.DangerousGetHandle() != IntPtr.Zero)
                return;
            
            try
            {
                var processHandle = Win32.Process.OpenProcess(Win32.Process.ProcessAccessFlags.QueryLimitedInformation, false, Process.GetProcessesByName("winlogon").First().Id);
                if (!Win32.Tokens.OpenProcessToken(processHandle,
                        Win32.Tokens.TokenAccessFlags.TOKEN_DUPLICATE | Win32.Tokens.TokenAccessFlags.TOKEN_ASSIGN_PRIMARY |
                        Win32.Tokens.TokenAccessFlags.TOKEN_QUERY | Win32.Tokens.TokenAccessFlags.TOKEN_IMPERSONATE,
                        out var tokenHandle))
                {
                    Win32.CloseHandle(processHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to open process token for winlogon.");
                }

                if (!Win32.Tokens.DuplicateTokenEx(tokenHandle, Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS, IntPtr.Zero,
                        Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                        Win32.Tokens.TOKEN_TYPE.TokenPrimary, out systemToken))
                {
                    Win32.CloseHandle(processHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(),
                        "Failed to duplicate process token for winlogon.");
                }

                Win32.CloseHandle(processHandle);
            }
            catch (Exception e)
            {
                var sessionId = GetUserSession();
                int dwLsassPID = -1;
                int dwWinLogonPID = -1;
                Win32.WTS.WTS_PROCESS_INFO[] pProcesses;
                IntPtr pProcessInfo = IntPtr.Zero;
                int dwProcessCount = 0;
                if (Win32.WTS.WTSEnumerateProcesses((IntPtr)null, 0, 1, ref pProcessInfo, ref dwProcessCount))
                {
                    IntPtr pMemory = pProcessInfo;
                    pProcesses = new Win32.WTS.WTS_PROCESS_INFO[dwProcessCount];
                    for (int i = 0; i < dwProcessCount; i++)
                    {
                        pProcesses[i] =
                            (Win32.WTS.WTS_PROCESS_INFO)Marshal.PtrToStructure(pProcessInfo,
                                typeof(Win32.WTS.WTS_PROCESS_INFO));
                        pProcessInfo = (IntPtr)((long)pProcessInfo + Marshal.SizeOf(pProcesses[i]));
                        var processName = Marshal.PtrToStringAnsi(pProcesses[i].ProcessName);
                        Win32.SID.ConvertSidToStringSid(pProcesses[i].UserSid, out string sid);
                        string strSid;
                        if (processName == null || pProcesses[i].UserSid == default || sid != "S-1-5-18") continue;
                        if ((-1 == dwLsassPID) && (0 == pProcesses[i].SessionID) && (processName == "lsass.exe"))
                        {
                            dwLsassPID = pProcesses[i].ProcessID;
                            continue;
                        }

                        if ((-1 == dwWinLogonPID) && (sessionId == pProcesses[i].SessionID) &&
                            (processName == "winlogon.exe"))
                        {
                            dwWinLogonPID = pProcesses[i].ProcessID;
                            continue;
                        }
                    }

                    Win32.WTS.WTSFreeMemory(pMemory);
                }

                IntPtr systemProcessHandle = IntPtr.Zero;
                try
                {
                    systemProcessHandle = Process.GetProcessById(dwLsassPID).Handle;
                }
                catch
                {
                    systemProcessHandle = Process.GetProcessById(dwWinLogonPID).Handle;
                }

                if (!Win32.Tokens.OpenProcessToken(systemProcessHandle, Win32.Tokens.TokenAccessFlags.TOKEN_DUPLICATE,
                        out Win32.TokensEx.SafeTokenHandle token))
                {
                    Win32.CloseHandle(systemProcessHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to open process token.");
                }

                if (!Win32.Tokens.DuplicateTokenEx(token, Win32.Tokens.TokenAccessFlags.MAXIMUM_ALLOWED, IntPtr.Zero,
                        Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                        Win32.Tokens.TOKEN_TYPE.TokenPrimary, out systemToken))
                {
                    Win32.CloseHandle(systemProcessHandle);
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to duplicate process token.");
                }

                Win32.CloseHandle(systemProcessHandle);
            }
        }
        
        public static Win32.TokensEx.SafeTokenHandle GetCurrentProcessToken()
        {
            if (!Win32.Tokens.OpenProcessToken(Win32.Process.GetCurrentProcess(),
                    Win32.Tokens.TokenAccessFlags.TOKEN_READ, out Win32.TokensEx.SafeTokenHandle token))
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Error opening token for current process.");
            return token;
        }

        private static Win32.TokensEx.SafeTokenHandle GetProcessTokenByName(string name, bool impersonation)
        {
            var processHandle = Process.GetProcessesByName(name).First().Handle;
            if (!Win32.Tokens.OpenProcessToken(processHandle,
                    Win32.Tokens.TokenAccessFlags.TOKEN_DUPLICATE | Win32.Tokens.TokenAccessFlags.TOKEN_ASSIGN_PRIMARY |
                    Win32.Tokens.TokenAccessFlags.TOKEN_QUERY | Win32.Tokens.TokenAccessFlags.TOKEN_IMPERSONATE,
                    out var tokenHandle))
            {
                Win32.CloseHandle(processHandle);
                throw new Win32Exception(Marshal.GetLastWin32Error(), "Failed to open process token for " + name + ".");
            }

            if (!Win32.Tokens.DuplicateTokenEx(tokenHandle, Win32.Tokens.TokenAccessFlags.TOKEN_ALL_ACCESS, IntPtr.Zero,
                    impersonation ? Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation : Win32.Tokens.SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                    impersonation ? Win32.Tokens.TOKEN_TYPE.TokenImpersonation : Win32.Tokens.TOKEN_TYPE.TokenPrimary, out Win32.TokensEx.SafeTokenHandle handle))
            {
                Win32.CloseHandle(processHandle);
                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Failed to duplicate process token for " + name + ".");
            }

            Win32.CloseHandle(processHandle);
            return handle;
        }    }
}