while (i > 0) and (Str[i] = ' ') do
        i := i - 1;
    Result := Copy(Str, 1, i);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
function LTrim(Str : String) : String;
var
    i : Integer;
begin
    if Str[1] <> ' ' then             { Petite optimisation: pas d'espace   }
        Result := Str
    else begin
        i := 1;
        while (i <= Length(Str)) and (Str[i] = ' ') do
            i := i + 1;
        Result := Copy(Str, i, Length(Str) - i + 1);
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
function Trim(Str : String) : String;
begin
    Result := LTrim(Rtrim(Str));
end;
{$ENDIF}


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
function stpblk(PValue : PChar) : PChar;
begin
    Result := PValue;
    while Result^ in [' ', #9, #10, #13] do
        Inc(Result);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
function atoi(PValue : PChar) : Integer;
begin
    Result := 0;
    PValue := stpblk(PValue);
    while PValue^ in ['0'..'9'] do begin
        Result := Result * 10 + ord(PValue^) - ord('0');
        Inc(PValue);
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
constructor TCustomPop3Cli.Create(AOwner : TComponent);
begin
    inherited Create(AOwner);
    FWindowHandle            := AllocateHWnd(WndProc);
    FWSocket                 := TWSocket.Create(nil);
    FWSocket.OnSessionClosed := WSocketSessionClosed;
    FProtocolState           := pop3Disconnected;
    FState                   := pop3Ready;
    FPort                    := 'pop3';
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
destructor TCustomPop3Cli.Destroy;
begin
    if Assigned(FWSocket) then begin
        FWSocket.Destroy;
        FWSocket := nil;
    end;
    DeallocateHWnd(FWindowHandle);
    inherited Destroy;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WndProc(var MsgRec: TMessage);
begin
     with MsgRec do begin
         case Msg of
         WM_POP3_REQUEST_DONE : WMPop3RequestDone(MsgRec);
         else
             Result := DefWindowProc(Handle, Msg, wParam, lParam);
         end;
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WMPop3RequestDone(var msg: TMessage);
begin
    if Assigned(FOnRequestDone) then
        FOnRequestDone(Self, FRequestType, Msg.LParam);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.Notification(AComponent: TComponent; Operation: TOperation);
begin
    inherited Notification(AComponent, Operation);
    if Operation = opRemove then begin
        if AComponent = FWSocket then
            FWSocket := nil;
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WSocketDnsLookupDone(Sender: TObject; Error: Word);
begin
    if Error <> 0 then begin
        FLastResponse  := '-ERR ' + WSocketErrorDesc(Error) +
                          ' (Winsock error #' + IntToStr(Error) + ')';
        FStatusCode    := 500;
        FRequestResult := Error;      { V2.02 }
        SetErrorMessage;
        TriggerRequestDone(Error);
    end
    else begin
        FWSocket.Addr  := FWSocket.DnsResult;
        FWSocket.Proto := 'tcp';
        FWSocket.Port  := FPort;
        FWSocket.OnSessionConnected := WSocketSessionConnected;
        FWSocket.OnDataAvailable    := WSocketDataAvailable;
        StateChange(pop3Connecting);
        try
            FWSocket.Connect;
        except
            on E:Exception do begin
                FLastResponse  := '-ERR ' + E.ClassName + ': ' + E.Message;
                FStatusCode    := 500;
                FRequestResult := FStatusCode;
                SetErrorMessage;
                TriggerRequestDone(FStatusCode);
            end;
        end
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WSocketSessionConnected(Sender: TObject; Error: Word);
begin
    { Do not trigger the client SessionConnected from here. We must wait }
    { to have received the server banner.                                }
    if Error <> 0 then begin
        FLastResponse  := '-ERR ' + WSocketErrorDesc(Error) +
                          ' (Winsock error #' + IntToStr(Error) + ')';
        FStatusCode    := 500;
        FConnected     := FALSE;
        FRequestResult := Error;      { V2.02 }
        SetErrorMessage;              { V2.03 }
        TriggerRequestDone(Error);
        FWSocket.Close;
        StateChange(pop3Ready);
    end
    else begin
        FConnected := TRUE;
        StateChange(pop3WaitingBanner);
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WSocketSessionClosed(Sender : TObject; Error : WORD);
begin
    FConnected := FALSE;
    TriggerSessionClosed(Error);
    TriggerRequestDone(WSAEINTR);
    FProtocolState := pop3Disconnected;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.WSocketDataAvailable(Sender: TObject; Error: Word);
var
    Len  : Integer;
    I, J : Integer;
begin
    Len := FWSocket.Receive(@FReceiveBuffer[FReceiveLen],
                            sizeof(FReceiveBuffer) - FReceiveLen - 1);

    if Len <= 0 then
        Exit;

    FReceiveBuffer[FReceiveLen + Len] := #0;
    FReceiveLen := FReceiveLen + Len;

    while FReceiveLen > 0 do begin
        { Search CRLF pair. We can't use Pos because it stops at first #0 }
        I := 1;
        while (I < FReceiveLen) and
              (FReceiveBuffer[I - 1] <> #13) and (FReceiveBuffer[I] <> #10) do
            Inc(I);
        if I >= FReceiveLen then
            break;                   { CRLF not found }

{$IFDEF NEVER}
        I := Pos(#13#10, FReceiveBuffer);
        if I <= 0 then
            break;
        if I > FReceiveLen then
            break;
{$ENDIF}
        { Found a CRLF. Extract data from buffer }
        FLastResponse := Copy(FReceiveBuffer, 1, I - 1);
        TriggerResponse(FLastResponse);

{$IFDEF DUMP}
        FDumpBuf := '>|';
        FDumpStream.WriteBuffer(FDumpBuf[1], Length(FDumpBuf));
        FDumpStream.WriteBuffer(FLastResponse[1], Length(FLastResponse));
        FDumpBuf := '|' + #13#10;
        FDumpStream.WriteBuffer(FDumpBuf[1], Length(FDumpBuf));
{$ENDIF}
{$IFDEF VER80}
        { Add a nul byte at the end of string for Delphi 1 }
        FLastResponse[Length(FLastResponse) + 1] := #0;
{$ENDIF}
        FReceiveLen := FReceiveLen - I - 1;
        if FReceiveLen > 0 then
            Move(FReceiveBuffer[I + 1], FReceiveBuffer[0], FReceiveLen + 1);

        if FState = pop3WaitingBanner then begin
            DisplayLastResponse;
            if not OkResponse then begin
                SetErrorMessage;
                FRequestResult := FStatusCode;
                FWSocket.Close;
                Exit;
            end;
            I := Pos('<', FLastResponse);
            J := Pos('>', Copy(FLastResponse, I, Length(FLastREsponse)));
            if (I > 0) and (J > 0) then
                FTimeStamp := Copy(FLastResponse, I, J);

            FProtocolState := pop3WaitingUser;
            StateChange(pop3Connected);
            TriggerSessionConnected(Error);

            if Assigned(FWhenConnected) then
                FWhenConnected
            else begin
                TriggerRequestDone(0);
            end;
        end
        else if FState = pop3WaitingResponse then begin
            if Assigned(FNext) then
                FNext
            else
                raise Pop3Exception.Create('Program error: FNext is nil');
        end
        else begin
            { Unexpected data received }
            DisplayLastResponse;
        end;
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerResponse(Msg : String);
begin
    if Assigned(FOnResponse) then
        FOnResponse(Self, Msg);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerStateChange;
begin
    if Assigned(FOnStateChange) then
        FOnStateChange(Self);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerRequestDone(Error: Word);
begin
    { Special processing for Quit (Roger Morton 24-12-99) }
    if FRequestType = pop3Quit then begin
        if FWaitingOnQuit then
            { When the second RqDone arrives (from WSocketSessionClosed),   }
            { treat it as a normal event by setting a zero Error code       }
            Error := 0
        else begin
            { When the first RqDone arrives, set the FWaitingOnQuit flag so }
            { we're ready to handle a second RqDone.                        }
            { Take no other action (in particular, we don't advise the user }
            { that the first RqDone has happened)                           }
            FWaitingOnQuit := True;
      	    Exit;
        end;
        { Fall down here for all normal RqDone, and after the second RqDone }
	{ following a Quit                                                  }
        FWaitingOnQuit := False;
    end;

    if not FRequestDoneFlag then begin
        FRequestDoneFlag := TRUE;
        if Assigned(FNextRequest) then begin
            if FState <> pop3Abort then
                StateChange(pop3InternalReady);
            FNextRequest;
        end
        else begin
            StateChange(pop3Ready);
            { Restore the lastresponse saved before quit command }
            if FHighLevelFlag and (FStatusCodeSave >= 0) then begin
                 FLastResponse := FLastResponseSave;
                 FStatusCode   := FStatusCodeSave;
            end;
            FHighLevelFlag := FALSE;
            PostMessage(Handle, WM_POP3_REQUEST_DONE, 0, Error);
        end;
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerDisplay(Msg : String);
begin
    if Assigned(FOnDisplay) then
        FOnDisplay(Self, Msg);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerSessionConnected(Error : Word);
begin
    if Assigned(FOnSessionConnected) then
        FOnSessionConnected(Self, Error);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.TriggerSessionClosed(Error : Word);
begin
    if Assigned(FOnSessionClosed) then
        FOnSessionClosed(Self, Error);
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TCustomPop3Cli.DoHighLevelAsync;
begin
{$IFDEF TRACE} TriggerDisplay('! HighLevelAsync ' + IntToStr(FRequestResult)); {$ENDIF}
    if FState = pop3Abort then begin
        {$IFDEF TRACE} TriggerDisplay('! Abort detected'); {$ENDIF}
        FFctSet := [];
        FHighLevelResult := 426;
        FErrorMessage    := '426 Operation aborted.';
    end;

    FNextRequest := DoHighLevelAsync;

    if FRequestResult <> 0 then begin
        { Previous command had errors }
        FHighLevelResult := FRequestResult;
        if (FFctPrv = pop3FctQuit) or (not (pop3FctQuit in FFctSet)) then
            FFctSet := []
        else
            FFctSet := [pop3FctQuit];
    end;

    if pop3FctConnect in FFctSet then begin
        FFctPrv := pop3FctConnect;
        FFctSet := FFctSet - [FFctPrv];
        Connect;
        Exit;
    end;

    if pop3FctUser in FFctSet then begin
        FFctPrv := pop3FctUser;
        FFctSet := FFctSet - [FFctPrv];
        User;
        Exit;
    end;

    if pop3FctPass in FFctSet then begin
        FFctPrv := pop3FctPass;
        FFctSet := FFctSet - [FFctPrv];
        Pass;
        Exit;
    end;

    if pop3FctRPop in FFctSet then begin
        FFctPrv := pop3FctRPop;
        FFctSet := FFctSet - [FFctPrv];
        RPop;
        Exit;
    end;

    if pop3FctDele in FFctSet then begin
        FFctPrv := pop3FctDele;
        FFctSet := FFctSet - [FFctPrv];
        Dele;
        Exit;
    end;

    if pop3FctNoop in FFctSet then begin
        FFctPrv := pop3FctNoop;
        FFctSet := FFctSet - [FFctPrv];
        Noop;
        Exit;
    end;

    if pop3FctList in FFctSet then begin
        FFctPrv := pop3FctList;
        FFctSet := FFctSet - [FFctPrv];
        List;
        Exit;
    end;