// created on 6/14/2002 at 7:56 PM

// Npgsql.NpgsqlState.cs
//
// Author:
// 	Dave Joyner <d4ljoyn@yahoo.com>
//
//	Copyright (C) 2002 The Npgsql Development Team
//	npgsql-general@gborg.postgresql.org
//	http://gborg.postgresql.org/project/npgsql/projdisplay.php
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


using System;
using System.Data;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Collections;
using System.Text;
using System.Resources;


namespace Npgsql
{
    ///<summary> This class represents the base class for the state pattern design pattern
    /// implementation.
    /// </summary>
    ///

    internal abstract class NpgsqlState
    {
        private readonly String CLASSNAME = "NpgsqlState";
        protected static ResourceManager resman = new ResourceManager(typeof(NpgsqlState));

        internal NpgsqlState()
        {
        }

        public virtual void Open(NpgsqlConnector context)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Startup(NpgsqlConnector context)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Authenticate(NpgsqlConnector context, string password)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Query(NpgsqlConnector context, NpgsqlCommand command)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Ready( NpgsqlConnector context )
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void FunctionCall(NpgsqlConnector context, NpgsqlCommand command)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Parse(NpgsqlConnector context, NpgsqlParse parse)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Flush(NpgsqlConnector context)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Sync(NpgsqlConnector context)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Bind(NpgsqlConnector context, NpgsqlBind bind)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        public virtual void Execute(NpgsqlConnector context, NpgsqlExecute execute)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        
        public virtual void Describe(NpgsqlConnector context, NpgsqlDescribe describe)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }
        
        public virtual void CancelRequest(NpgsqlConnector context)
        {
            throw new InvalidOperationException("Internal Error! " + this);
        }

        public virtual void Close( NpgsqlConnector context )
        {
            if (this != NpgsqlClosedState.Instance)
            {
                try
                {
                    context.Stream.Close();
                }
                catch {}

                context.Stream = null;
            ChangeState( context, NpgsqlClosedState.Instance )
                ;
            }
        }

        ///<summary>
        ///This method is used by the states to change the state of the context.
        /// </summary>
        protected virtual void ChangeState(NpgsqlConnector context, NpgsqlState newState)
        {
            NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "ChangeState");
            context.CurrentState = newState;
        }

        ///<summary>
        /// This method is responsible to handle all protocol messages sent from the backend.
        /// It holds all the logic to do it.
        /// To exchange data, it uses a Mediator object from which it reads/writes information
        /// to handle backend requests.
        /// </summary>
        ///
        internal virtual void ProcessBackendResponses( NpgsqlConnector context )
        {

            try
            {
                
                // Process commandTimeout behavior.
                
                if ((context.Mediator.CommandTimeout > 0) && (!context.Socket.Poll(1000000 * context.Mediator.CommandTimeout, SelectMode.SelectRead)))
                {
                    // If timeout occurs when establishing the session with server then
                    // throw an exception instead of trying to cancel query. This helps to prevent loop as CancelRequest will also try to stablish a connection and sends commands.
                    if ((this is NpgsqlStartupState || this is NpgsqlConnectedState))
                        throw new NpgsqlException(resman.GetString("Exception_ConnectionTimeout"));
                   else
                       context.CancelRequest();

                }
                    
                
                
                switch (context.BackendProtocolVersion)
                {
                case ProtocolVersion.Version2 :
                    ProcessBackendResponses_Ver_2(context);
                    break;

                case ProtocolVersion.Version3 :
                    ProcessBackendResponses_Ver_3(context);
                    break;

                }
            }
            finally
            {
                // reset expectations right after getting new responses
                context.Mediator.ResetExpectations();
            }
        }

        protected virtual void ProcessBackendResponses_Ver_2( NpgsqlConnector context )
        {
            NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "ProcessBackendResponses");

            Stream 	stream = context.Stream;
            NpgsqlMediator mediator = context.Mediator;

            // Often used buffer
            Byte[] inputBuffer = new Byte[ 4 ];

            Boolean readyForQuery = false;

            byte[] asciiRowBytes = new byte[300];
            char[] asciiRowChars = new char[300];

            while (!readyForQuery)
            {
                // Check the first Byte of response.
                switch ( stream.ReadByte() )
                {
                case NpgsqlMessageTypes_Ver_2.ErrorResponse :

                    {
                        NpgsqlError error = new NpgsqlError(context.BackendProtocolVersion);
                        error.ReadFromStream(stream, context.Encoding);
                        error.ErrorSql = mediator.SqlSent;

                        mediator.Errors.Add(error);

                        NpgsqlEventLog.LogMsg(resman, "Log_ErrorResponse", LogLevel.Debug, error.Message);
                    }

                    // Return imediately if it is in the startup state or connected state as
                    // there is no more messages to consume.
                    // Possible error in the NpgsqlStartupState:
                    //		Invalid password.
                    // Possible error in the NpgsqlConnectedState:
                    //		No pg_hba.conf configured.

                    if (! mediator.RequireReadyForQuery)
                    {
                        return;
                    }

                    break;


                case NpgsqlMessageTypes_Ver_2.AuthenticationRequest :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "AuthenticationRequest");

                    {
                        Int32 authType = PGUtil.ReadInt32(stream, inputBuffer);

                        if ( authType == NpgsqlMessageTypes_Ver_2.AuthenticationOk )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationOK", LogLevel.Debug);

                            break;
                        }

                        if ( authType == NpgsqlMessageTypes_Ver_2.AuthenticationClearTextPassword )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationClearTextRequest", LogLevel.Debug);

                            // Send the PasswordPacket.

                            ChangeState( context, NpgsqlStartupState.Instance );
                            context.Authenticate(context.Password);

                            break;
                        }


                        if ( authType == NpgsqlMessageTypes_Ver_2.AuthenticationMD5Password )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationMD5Request", LogLevel.Debug);
                            // Now do the "MD5-Thing"
                            // for this the Password has to be:
                            // 1. md5-hashed with the username as salt
                            // 2. md5-hashed again with the salt we get from the backend


                            MD5 md5 = MD5.Create();


                            // 1.
                            byte[] passwd = context.Encoding.GetBytes(context.Password);
                            byte[] saltUserName = context.Encoding.GetBytes(context.UserName);

                            byte[] crypt_buf = new byte[passwd.Length + saltUserName.Length];

                            passwd.CopyTo(crypt_buf, 0);
                            saltUserName.CopyTo(crypt_buf, passwd.Length);



                            StringBuilder sb = new StringBuilder ();
                            byte[] hashResult = md5.ComputeHash(crypt_buf);
                            foreach (byte b in hashResult)
                            sb.Append (b.ToString ("x2"));


                            String prehash = sb.ToString();

                            byte[] prehashbytes = context.Encoding.GetBytes(prehash);



                            byte[] saltServer = new byte[4];
                            stream.Read(saltServer, 0, 4);
                            // Send the PasswordPacket.
                            ChangeState( context, NpgsqlStartupState.Instance );


                            // 2.

                            crypt_buf = new byte[prehashbytes.Length + saltServer.Length];
                            prehashbytes.CopyTo(crypt_buf, 0);
                            saltServer.CopyTo(crypt_buf, prehashbytes.Length);

                            sb = new StringBuilder ("md5"); // This is needed as the backend expects md5 result starts with "md5"
                            hashResult = md5.ComputeHash(crypt_buf);
                            foreach (byte b in hashResult)
                            sb.Append (b.ToString ("x2"));

                            context.Authenticate(sb.ToString ());

                            break;
                        }

                        // Only AuthenticationClearTextPassword and AuthenticationMD5Password supported for now.

                        mediator.Errors.Add(new NpgsqlError(context.BackendProtocolVersion, String.Format(resman.GetString("Exception_AuthenticationMethodNotSupported"), authType)));
                    }

                    return;

                case NpgsqlMessageTypes_Ver_2.RowDescription:
                    // This is the RowDescription message.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "RowDescription");

                    {
                        NpgsqlRowDescription rd = new NpgsqlRowDescription(context.BackendProtocolVersion);
                        rd.ReadFromStream(stream, context.Encoding, context.OidToNameMapping);

                        // Initialize the array list which will contain the data from this rowdescription.
                        mediator.AddRowDescription(rd);
                    }

                    // Now wait for the AsciiRow messages.
                    break;

                case NpgsqlMessageTypes_Ver_2.AsciiRow:
                    // This is the AsciiRow message.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "AsciiRow");

                    {
                        NpgsqlAsciiRow asciiRow = new NpgsqlAsciiRow(context.Mediator.LastRowDescription, context.BackendProtocolVersion, asciiRowBytes, asciiRowChars);
                        asciiRow.ReadFromStream(stream, context.Encoding);

                        // Add this row to the rows array.
                        mediator.AddAsciiRow(asciiRow);
                    }

                    // Now wait for CompletedResponse message.
                    break;

                case NpgsqlMessageTypes_Ver_2.BinaryRow:
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "BinaryRow");

                    {
                        NpgsqlBinaryRow binaryRow = new NpgsqlBinaryRow(context.Mediator.LastRowDescription);
                        binaryRow.ReadFromStream(stream, context.Encoding);

                        mediator.AddBinaryRow(binaryRow);
                    }

                    break;

                case NpgsqlMessageTypes_Ver_2.ReadyForQuery :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "ReadyForQuery");
                    readyForQuery = true;
                    ChangeState( context, NpgsqlReadyState.Instance );
                    break;

                case NpgsqlMessageTypes_Ver_2.BackendKeyData :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "BackendKeyData");
                    // BackendKeyData message.
                    NpgsqlBackEndKeyData backend_keydata = new NpgsqlBackEndKeyData(context.BackendProtocolVersion);
                    backend_keydata.ReadFromStream(stream);
                    mediator.SetBackendKeydata(backend_keydata);


                    // Wait for ReadForQuery message
                    break;
                    ;

                case NpgsqlMessageTypes_Ver_2.NoticeResponse :

                    {
                        NpgsqlError notice = new NpgsqlError(context.BackendProtocolVersion);
                        notice.ReadFromStream(stream, context.Encoding);

                        mediator.Notices.Add(notice);

                        NpgsqlEventLog.LogMsg(resman, "Log_NoticeResponse", LogLevel.Debug, notice.Message);
                    }

                    // Wait for ReadForQuery message
                    break;

                case NpgsqlMessageTypes_Ver_2.CompletedResponse :
                    // This is the CompletedResponse message.
                    // Get the string returned.


                    String result = PGUtil.ReadString(stream, context.Encoding);

                    NpgsqlEventLog.LogMsg(resman, "Log_CompletedResponse", LogLevel.Debug, result);
                    // Add result from the processing.

                    mediator.AddCompletedResponse(result);

                    // Now wait for ReadyForQuery message.
                    break;

                case NpgsqlMessageTypes_Ver_2.CursorResponse :
                    // This is the cursor response message.
                    // It is followed by a C NULL terminated string with the name of
                    // the cursor in a FETCH case or 'blank' otherwise.
                    // In this case it should be always 'blank'.
                    // [FIXME] Get another name for this function.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "CursorResponse");

                    String cursorName = PGUtil.ReadString(stream, context.Encoding);
                    // Continue waiting for ReadyForQuery message.
                    break;

                case NpgsqlMessageTypes_Ver_2.EmptyQueryResponse :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "EmptyQueryResponse");
                    PGUtil.ReadString(stream, context.Encoding);
                    break;

                case NpgsqlMessageTypes_Ver_2.NotificationResponse  :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "NotificationResponse");

                    Int32 PID = PGUtil.ReadInt32(stream, inputBuffer);
                    String notificationResponse = PGUtil.ReadString( stream, context.Encoding );
                    mediator.AddNotification(new NpgsqlNotificationEventArgs(PID, notificationResponse));
                    
                    if (context.IsNotificationThreadRunning)
                        readyForQuery = true;

                    // Wait for ReadForQuery message
                    break;

                case -1:
                    // Connection broken. Mono returns -1 instead of throw an exception as ms.net does.
                    throw new IOException();

                default :
                    // This could mean a number of things
                    //   We've gotten out of sync with the backend?
                    //   We need to implement this type?
                    //   Backend has gone insane?
                    // FIXME
                    // what exception should we really throw here?
                    throw new NotSupportedException("Backend sent unrecognized response type");

                }
            }
        }

        protected virtual void ProcessBackendResponses_Ver_3( NpgsqlConnector context )
        {
            NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "ProcessBackendResponses");

            Stream 	stream = context.Stream;
            NpgsqlMediator mediator = context.Mediator;

            // Often used buffers
            Byte[] inputBuffer = new Byte[ 4 ];
            String Str;

            Boolean readyForQuery = false;

            byte[] asciiRowBytes = new byte[300];
            char[] asciiRowChars = new char[300];

            while (!readyForQuery)
            {
                // Check the first Byte of response.
                Int32 message = stream.ReadByte();
                switch ( message )
                {
                case NpgsqlMessageTypes_Ver_3.ErrorResponse :

                    {
                        NpgsqlError error = new NpgsqlError(context.BackendProtocolVersion);
                        error.ReadFromStream(stream, context.Encoding);
                        error.ErrorSql = mediator.SqlSent;

                        mediator.Errors.Add(error);

                        NpgsqlEventLog.LogMsg(resman, "Log_ErrorResponse", LogLevel.Debug, error.Message);
                    }

                    // Return imediately if it is in the startup state or connected state as
                    // there is no more messages to consume.
                    // Possible error in the NpgsqlStartupState:
                    //		Invalid password.
                    // Possible error in the NpgsqlConnectedState:
                    //		No pg_hba.conf configured.

                    if (! mediator.RequireReadyForQuery)
                    {
                        return;
                    }

                    break;


                case NpgsqlMessageTypes_Ver_3.AuthenticationRequest :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "AuthenticationRequest");

                    // Eat length
                    PGUtil.ReadInt32(stream, inputBuffer);

                    {
                        Int32 authType = PGUtil.ReadInt32(stream, inputBuffer);

                        if ( authType == NpgsqlMessageTypes_Ver_3.AuthenticationOk )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationOK", LogLevel.Debug);

                            break;
                        }

                        if ( authType == NpgsqlMessageTypes_Ver_3.AuthenticationClearTextPassword )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationClearTextRequest", LogLevel.Debug);

                            // Send the PasswordPacket.

                            ChangeState( context, NpgsqlStartupState.Instance );
                            context.Authenticate(context.Password);

                            break;
                        }


                        if ( authType == NpgsqlMessageTypes_Ver_3.AuthenticationMD5Password )
                        {
                            NpgsqlEventLog.LogMsg(resman, "Log_AuthenticationMD5Request", LogLevel.Debug);
                            // Now do the "MD5-Thing"
                            // for this the Password has to be:
                            // 1. md5-hashed with the username as salt
                            // 2. md5-hashed again with the salt we get from the backend


                            MD5 md5 = MD5.Create();


                            // 1.
                            byte[] passwd = context.Encoding.GetBytes(context.Password);
                            byte[] saltUserName = context.Encoding.GetBytes(context.UserName);

                            byte[] crypt_buf = new byte[passwd.Length + saltUserName.Length];

                            passwd.CopyTo(crypt_buf, 0);
                            saltUserName.CopyTo(crypt_buf, passwd.Length);



                            StringBuilder sb = new StringBuilder ();
                            byte[] hashResult = md5.ComputeHash(crypt_buf);
                            foreach (byte b in hashResult)
                            sb.Append (b.ToString ("x2"));


                            String prehash = sb.ToString();

                            byte[] prehashbytes = context.Encoding.GetBytes(prehash);



                            stream.Read(inputBuffer, 0, 4);
                            // Send the PasswordPacket.
                            ChangeState( context, NpgsqlStartupState.Instance );


                            // 2.

                            crypt_buf = new byte[prehashbytes.Length + 4];
                            prehashbytes.CopyTo(crypt_buf, 0);
                            inputBuffer.CopyTo(crypt_buf, prehashbytes.Length);

                            sb = new StringBuilder ("md5"); // This is needed as the backend expects md5 result starts with "md5"
                            hashResult = md5.ComputeHash(crypt_buf);
                            foreach (byte b in hashResult)
                            sb.Append (b.ToString ("x2"));

                            context.Authenticate(sb.ToString ());

                            break;
                        }

                        // Only AuthenticationClearTextPassword and AuthenticationMD5Password supported for now.
                        mediator.Errors.Add(new NpgsqlError(context.BackendProtocolVersion, String.Format(resman.GetString("Exception_AuthenticationMethodNotSupported"), authType)));
                    }

                    return;

                case NpgsqlMessageTypes_Ver_3.RowDescription:
                    // This is the RowDescription message.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "RowDescription");
                    {
                        NpgsqlRowDescription rd = new NpgsqlRowDescription(context.BackendProtocolVersion);
                        rd.ReadFromStream(stream, context.Encoding, context.OidToNameMapping);

                        mediator.AddRowDescription(rd);
                    }

                    // Now wait for the AsciiRow messages.
                    break;
                case NpgsqlMessageTypes_Ver_3.ParameterDescription:
                    
                    // Do nothing,for instance,  just read...
                    int lenght = PGUtil.ReadInt32(stream, inputBuffer);
                    int nb_param = PGUtil.ReadInt16(stream, inputBuffer);
                    for (int i=0; i < nb_param; i++)
                    {
                        int typeoid = PGUtil.ReadInt32(stream, inputBuffer);
                    }
                    
                    break;

                case NpgsqlMessageTypes_Ver_3.DataRow:
                    // This is the AsciiRow message.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "DataRow");
                    {
                        NpgsqlAsciiRow asciiRow = new NpgsqlAsciiRow(context.Mediator.LastRowDescription, context.BackendProtocolVersion, asciiRowBytes, asciiRowChars);
                        asciiRow.ReadFromStream(stream, context.Encoding);

                        // Add this row to the rows array.
                        mediator.AddAsciiRow(asciiRow);
                    }

                    // Now wait for CompletedResponse message.
                    break;

                case NpgsqlMessageTypes_Ver_3.ReadyForQuery :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "ReadyForQuery");

                    // Possible status bytes returned:
                    //   I = Idle (no transaction active).
                    //   T = In transaction, ready for more.
                    //   E = Error in transaction, queries will fail until transaction aborted.
                    // Just eat the status byte, we have no use for it at this time.
                    PGUtil.ReadInt32(stream, inputBuffer);
                    PGUtil.ReadString(stream, context.Encoding, 1);

                    readyForQuery = true;
                    ChangeState( context, NpgsqlReadyState.Instance );

                    break;

                case NpgsqlMessageTypes_Ver_3.BackendKeyData :

                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "BackendKeyData");
                    // BackendKeyData message.
                    NpgsqlBackEndKeyData backend_keydata = new NpgsqlBackEndKeyData(context.BackendProtocolVersion);
                    backend_keydata.ReadFromStream(stream);
                    mediator.SetBackendKeydata(backend_keydata);


                    // Wait for ReadForQuery message
                    break;

                case NpgsqlMessageTypes_Ver_3.NoticeResponse :

                    // Notices and errors are identical except that we
                    // just throw notices away completely ignored.
                    {
                        NpgsqlError notice = new NpgsqlError(context.BackendProtocolVersion);
                        notice.ReadFromStream(stream, context.Encoding);

                        mediator.Notices.Add(notice);

                        NpgsqlEventLog.LogMsg(resman, "Log_NoticeResponse", LogLevel.Debug, notice.Message);
                    }

                    // Wait for ReadForQuery message
                    break;

                case NpgsqlMessageTypes_Ver_3.CompletedResponse :
                    // This is the CompletedResponse message.
                    // Get the string returned.

                    PGUtil.ReadInt32(stream, inputBuffer);
                    Str = PGUtil.ReadString(stream, context.Encoding);

                    NpgsqlEventLog.LogMsg(resman, "Log_CompletedResponse", LogLevel.Debug, Str);

                    // Add result from the processing.
                    mediator.AddCompletedResponse(Str);

                    break;

                case NpgsqlMessageTypes_Ver_3.ParseComplete :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "ParseComplete");
                    // Just read up the message length.
                    PGUtil.ReadInt32(stream, inputBuffer);
                    readyForQuery = true;
                    break;

                case NpgsqlMessageTypes_Ver_3.BindComplete :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "BindComplete");
                    // Just read up the message length.
                    PGUtil.ReadInt32(stream, inputBuffer);
                    readyForQuery = true;
                    break;

                case NpgsqlMessageTypes_Ver_3.EmptyQueryResponse :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "EmptyQueryResponse");
                    PGUtil.ReadInt32(stream, inputBuffer);
                    break;

                case NpgsqlMessageTypes_Ver_3.NotificationResponse  :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "NotificationResponse");

                    // Eat the length
                    PGUtil.ReadInt32(stream, inputBuffer);
                    {
                        // Process ID sending notification
                        Int32 PID = PGUtil.ReadInt32(stream, inputBuffer);
                        // Notification string
                        String notificationResponse = PGUtil.ReadString( stream, context.Encoding );
                        // Additional info, currently not implemented by PG (empty string always), eat it
                        PGUtil.ReadString( stream, context.Encoding );
                        mediator.AddNotification(new NpgsqlNotificationEventArgs(PID, notificationResponse));
                    }
                    
                    if (context.IsNotificationThreadRunning)
                        readyForQuery = true;

                    // Wait for ReadForQuery message
                    break;

                case NpgsqlMessageTypes_Ver_3.ParameterStatus :
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "ParameterStatus");
                    NpgsqlParameterStatus parameterStatus = new NpgsqlParameterStatus();
                    parameterStatus.ReadFromStream(stream, context.Encoding);

                    NpgsqlEventLog.LogMsg(resman, "Log_ParameterStatus", LogLevel.Debug, parameterStatus.Parameter, parameterStatus.ParameterValue);

                    mediator.AddParameterStatus(parameterStatus.Parameter, parameterStatus);

                    if (parameterStatus.Parameter == "server_version")
                    {
                        // Add this one under our own name so that if the parameter name
                        // changes in a future backend version, we can handle it here in the
                        // protocol handler and leave everybody else put of it.
                        mediator.AddParameterStatus("__npgsql_server_version", parameterStatus);
                        //                        context.ServerVersionString = parameterStatus.ParameterValue;
                    }

                    break;
                case NpgsqlMessageTypes_Ver_3.NoData :
                    // This nodata message may be generated by prepare commands issued with queries which doesn't return rows
                    // for example insert, update or delete.
                    // Just eat the message.
                    NpgsqlEventLog.LogMsg(resman, "Log_ProtocolMessage", LogLevel.Debug, "ParameterStatus");
                    PGUtil.ReadInt32(stream, inputBuffer);
                    break;


                case -1:
		    // Connection broken. Mono returns -1 instead of throw an exception as ms.net does.
		    throw new IOException();

                default :
                    // This could mean a number of things
                    //   We've gotten out of sync with the backend?
                    //   We need to implement this type?
                    //   Backend has gone insane?
                    // FIXME
                    // what exception should we really throw here?
                    throw new NotSupportedException(String.Format("Backend sent unrecognized response type: {0}", (Char)message));

                }
            }
        }
    }
}
