function UserSessions()
{
    this._ObjectID = 'UserSessions';

    if (process.platform == 'win32') {
        this._marshal = require('_GenericMarshal');
        this._kernel32 = this._marshal.CreateNativeProxy('Kernel32.dll');
        this._kernel32.CreateMethod('GetLastError');
        this._wts = this._marshal.CreateNativeProxy('Wtsapi32.dll');
        this._wts.CreateMethod('WTSEnumerateSessionsA');
        this._wts.CreateMethod('WTSQuerySessionInformationA');
        this._wts.CreateMethod('WTSFreeMemory');
        this.SessionStates = ['Active', 'Connected', 'ConnectQuery', 'Shadow', 'Disconnected', 'Idle', 'Listening', 'Reset', 'Down', 'Init'];
        this.InfoClass =
            {
                'WTSInitialProgram': 0,
                'WTSApplicationName': 1,
                'WTSWorkingDirectory': 2,
                'WTSOEMId': 3,
                'WTSSessionId': 4,
                'WTSUserName': 5,
                'WTSWinStationName': 6,
                'WTSDomainName': 7,
                'WTSConnectState': 8,
                'WTSClientBuildNumber': 9,
                'WTSClientName': 10,
                'WTSClientDirectory': 11,
                'WTSClientProductId': 12,
                'WTSClientHardwareId': 13,
                'WTSClientAddress': 14,
                'WTSClientDisplay': 15,
                'WTSClientProtocolType': 16,
                'WTSIdleTime': 17,
                'WTSLogonTime': 18,
                'WTSIncomingBytes': 19,
                'WTSOutgoingBytes': 20,
                'WTSIncomingFrames': 21,
                'WTSOutgoingFrames': 22,
                'WTSClientInfo': 23,
                'WTSSessionInfo': 24,
                'WTSSessionInfoEx': 25,
                'WTSConfigInfo': 26,
                'WTSValidationInfo': 27,
                'WTSSessionAddressV4': 28,
                'WTSIsRemoteSession': 29
            };

        this.getSessionAttribute = function getSessionAttribute(sessionId, attr)
        {
            var buffer = this._marshal.CreatePointer();
            var bytesReturned = this._marshal.CreateVariable(4);

            if (this._wts.WTSQuerySessionInformationA(0, sessionId, attr, buffer, bytesReturned).Val == 0)
            {
                throw ('Error calling WTSQuerySessionInformation: ' + this._kernel32.GetLastError.Val);
            }

            var retVal = buffer.Deref().String;

            this._wts.WTSFreeMemory(buffer.Deref());
            return (retVal);
        };

        this.Current = function Current()
        {
            var retVal = {};
            var pinfo = this._marshal.CreatePointer();
            var count = this._marshal.CreateVariable(4);
            if (this._wts.WTSEnumerateSessionsA(0, 0, 1, pinfo, count).Val == 0)
            {
                throw ('Error calling WTSEnumerateSessionsA: ' + this._kernel32.GetLastError().Val);
            }

            for (var i = 0; i < count.toBuffer().readUInt32LE() ; ++i)
            {
                var info = pinfo.Deref().Deref(i * (this._marshal.PointerSize == 4 ? 12 : 24), this._marshal.PointerSize == 4 ? 12 : 24);
                var j = { SessionId: info.toBuffer().readUInt32LE() };
                j.StationName = info.Deref(this._marshal.PointerSize == 4 ? 4 : 8, this._marshal.PointerSize).Deref().String;
                j.State = this.SessionStates[info.Deref(this._marshal.PointerSize == 4 ? 8 : 16, 4).toBuffer().readUInt32LE()];
                if (j.State == 'Active') {
                    j.Username = this.getSessionAttribute(j.SessionId, this.InfoClass.WTSUserName);
                    j.Domain = this.getSessionAttribute(j.SessionId, this.InfoClass.WTSDomainName);
                }
                retVal[j.SessionId] = j;
            }

            this._wts.WTSFreeMemory(pinfo.Deref());
            return (retVal);
        };
    }
    else
    {
        this.Current = function Current()
        {
            return ({});
        }
    }
}

module.exports = new UserSessions();