--******************************************************************************
--*                                                                            *
--*  File:        TkSocket_00.lua                       Revision:  1.0         *
--*                                                                            *
--*  Purpose:     performs a DNS lookup                                        *
--*                                                                            *
--*  Creation:    09.03.2002                   Last Modification:  09.03.2002  *
--*                                                                            *
--*  Platform:    IBM-compatible PC running Windows 98SE                       *
--*                                                                            *
--*  Environment: Lua 4.0, TkLua 4.0                                           *
--*                                                                            *
--*  Author:      Andreas Rozek           Phone:  ++49 (711) 6770682           *
--*               Kirschblütenweg 15      Fax:    -                            *
--*             D-70569 Stuttgart         EMail:  Andreas.Rozek@T-Online.De    *
--*               Germany                                                      *
--*                                                                            *
--*  URL:         http://www.Andreas-Rozek.de/                                 *
--*                                                                            *
--*  Copyright:   the software is published under the "GNU Lesser General Pub- *
--*               lic  License" (see "http://www.fsf.org/copyleft/lesser.html" *
--*               for additional information)                                  *
--*                                                                            *
--*  Comments:    this is the first experiment with LuaSockets under TkLua 4.0 *
--*                                                                            *
--******************************************************************************

  dofile("Lua_02_Lib.lua");     -- provides an extended 'tostring' function etc.
  dofile("TkLua_00_Lib.lua");                    -- provides a simple Tk Console

  local Icon     = "./Lua.gif";-- specifying the file name is already sufficient
  local Title    = "TkSocket_00";
  local Subtitle = "performs a DNS lookup";
        Status   = "enter an IP address or a Host Name and press \"Resolve\"";

--******************************************************************************
--*                                                                            *
--* doLookup            callback function which performs the actual DNS lookup *
--*                                                                            *
--******************************************************************************

  function doLookup ()
    local Candidate = CandidateEntry.current;
      Candidate = gsub(Candidate, "^%s*", "");   -- removes leading white char.s
      Candidate = gsub(Candidate, "%s*$", "");  -- removes trailing white char.s
    if (Candidate == "") then
      tkmessagebox{
        title=%Title..": Input Error",
        message="No Host Name or IP Address given",
        icon="error", type="ok", default="ok"
      };
      setFields();           -- clears all relevant fields of the user interface
      return nil;                  -- 'return' without 'nil' produces an error!?
    end;

  --**** now perform the lookup ****

    local MessageWindow = tktoplevel{
      tklabel{image="./Info.gif", anchor="ne", width=16, height=16},
      tkmessage{
        "DNS Lookup running\nPlease wait...";
        width="20c", anchor="nw", font="-*-helvetica-bold-r-*--12"
      };
      side="left"               -- common layout attribute for all inner widgets
    };
    MessageWindow:title(%Title..": DNS Lookup running");
    MessageWindow:transient(MainWindow.tkname);  -- register window dependencies
    MessageWindow:show();                       -- also triggers a window layout
    MessageWindow:resizable(0,0);                -- disables window size changes
    MessageWindow:raise();              -- brings the window into the foreground

  --**** center this window within the main window (for user's convenience) ****

--  tkeval("update idletasks");               -- guarantee actual window display
    tkeval("update");            -- "update idletasks" doesn't seem to be enough

    local MainGeometry    = MainWindow:geometry();
      local _,_,MainW,MainH,MainX,MainY = strfind(MainGeometry[1],"^(%d+)x(%d+)([+-]?%d+)([+-]?%d+)");
    local MessageGeometry = MessageWindow:geometry();
      local _,_,MsgW,MsgH,MsgX,MsgY  = strfind(MessageGeometry[1],"^(%d+)x(%d+)([+-]?%d+)([+-]?%d+)");

    MsgX = max(0,floor(MainX+(MainW-MsgW)/2));
    MsgY = max(0,floor(MainY+(MainH-MsgH)/2));

    MessageWindow:geometry("+"..MsgX.."+"..MsgY);

  --**** prevent window from being closed by the user ****

    MessageWindow:protocol("WM_DELETE_WINDOW", "");

  --**** make this window "modal" ****

    MessageWindow:focus();
    MessageWindow:grab();

--  tkeval("update idletasks");               -- guarantee actual window display
    tkeval("update");            -- "update idletasks" doesn't seem to be enough

  --**** it's now time to perform the DNS lookup ****

    local Address,HostInfo = toip(Candidate);

    MainWindow:grab();                   -- releases the grab on "MessageWindow"
    MessageWindow:withdraw();                              -- removes the window

    if (Address == nil) then
      tkmessagebox{
        title=%Title..": DNS Lookup Error",
        message="DNS Lookup failed\nReason: \""..tostring(HostInfo).."\"",
        icon="error", type="ok", default="ok"
      };
      setFields(Candidate,nil,nil,nil,"DNS Lookup failed, reason: \""..tostring(HostInfo).."\"");
      return nil;                  -- 'return' without 'nil' produces an error!?
    end;

  --**** analyse any results ****

    local AliasList = "";
    if (HostInfo.alias ~= nil) and (getn(HostInfo.alias) > 0) then -- 2nd case is important!
      local AliasCount = getn(HostInfo.alias);
      for i = 1,AliasCount do
        AliasList = AliasList..HostInfo.alias[i];
        if (i < AliasCount) then AliasList = AliasList..", "; end;
      end;
    end;

    local AddressList = "";
    if (HostInfo.ip ~= nil) and (getn(HostInfo.ip) > 0) then       -- 2nd case is important!
      local AddressCount = getn(HostInfo.ip);
      for i = 1,AddressCount do
        AddressList = AddressList..HostInfo.ip[i];
        if (i < AddressCount) then AddressList = AddressList..", "; end;
      end;
    end;

    setFields(Candidate, HostInfo.name, AliasList, AddressList, Status);
  end;

--******************************************************************************
--*                                                                            *
--* setFields        (re)loads relevant fields of the graphical user interface *
--*                                                                            *
--******************************************************************************

  function setFields (Candidate, CanonicalName, AliasList, AddressList, Message)
    CandidateEntry.current = Candidate or "";

    CanonicalView.state = "normal";
      CanonicalView.current = CanonicalName or "";
    CanonicalView.state = "disabled";

    AliasView.state = "normal";
      AliasView.current = AliasList or "";
    AliasView.state = "disabled";

    AddressView.state = "normal";
      AddressView.current = AddressList or "";
    AddressView.state = "disabled";

    StatusBar.text = Message or Status;
  end;

--******************************************************************************
--*                                                                            *
--*                                main program                                *
--*                                                                            *
--******************************************************************************

--**** define window components ****

  local LabelFont = "-*-helvetica-bold-r-*--12";         -- just an abbreviation

  local IconLabel      = tklabel{image=Icon, anchor="center", width=32, height=32};
  local TitleLabel     = tklabel{Title;      anchor="e", font="-*-helvetica-bold-o-*--16"};
  local SubtitleLabel  = tklabel{Subtitle;   anchor="e", font="-*-helvetica-bold-r-*--12"};
  local UpperSeparator = tkframe{relief="sunken", borderwidth=2,        height=2};

  local CandidateLabel = tklabel{"Input:";          font=LabelFont};
        CandidateEntry = tkentry{width=30};
  local DNSButton      = tkbutton{"Resolve";        font=LabelFont, command="doLookup()"};
  local InputSeparator = tkframe{relief="sunken", borderwidth=2, height=2};
  local CanonicalLabel = tklabel{"Canonical Name:"; font=LabelFont};
        CanonicalView  = tkentry{state="disabled", background="SystemButtonFace"};
  local AliasLabel     = tklabel{"Alias List:";     font=LabelFont};
        AliasView      = tkentry{state="disabled", background="SystemButtonFace"};
  local AddressLabel   = tklabel{"Address List:";   font=LabelFont};
        AddressView    = tkentry{state="disabled", background="SystemButtonFace"};

  local LowerSeparator = tkframe{relief="sunken", borderwidth=2, height=2};
        StatusBar      = tklabel{Status; width=40, anchor="w", font="-*-helvetica-medium-r-*--11"};

--**** construct application window ****

  MainWindow = tkmain{
    tkframe{
      IconLabel,     {side="left"},
      TitleLabel,    {side="top", fill="x"},
      SubtitleLabel, {side="top", fill="x"}
    },               {side="top", fill="x"},
    UpperSeparator,  {side="top", fill="x"},
    tkframe{                   -- see below for some "fine-tuning" of this frame
      CandidateLabel, CandidateEntry, DNSButton, "/",
      InputSeparator,                            "/",
      CanonicalLabel, CanonicalView,             "/",
      AliasLabel,     AliasView,                 "/",
      AddressLabel,   AddressView;
      geoman="grid"
    },               {side="top", fill="both", expand=1},
    LowerSeparator,  {side="top", fill="x"},
    StatusBar,       {side="top", fill="x"}
  };

--**** provide a default for 'CandidateEntry' ****

  CandidateEntry.current="localhost";

--**** display application window ****

  MainWindow:title(Title.." - "..Subtitle);
  MainWindow:show();                            -- also triggers a window layout
--MainWindow:resizable(0,0);                     -- disables window size changes
--MainWindow:raise();                   -- brings the window into the foreground

--**** it's now time to fine-tune the display ****

  tkeval('grid configure '..CandidateLabel.tkname..' -sticky "e"         -pady 2');
  tkeval('grid configure '..CandidateEntry.tkname..'             -padx 2 -pady 2');
  tkeval('grid configure '..DNSButton.tkname..'                  -padx 2 -pady 2');
  tkeval('grid configure '..InputSeparator.tkname..' -columnspan 3 -sticky "ew"');
  tkeval('grid configure '..CanonicalLabel.tkname..' -sticky "e"');
  tkeval('grid configure '..CanonicalView.tkname..'  -columnspan 2 -sticky "ew" -padx 2 -pady 2');
  tkeval('grid configure '..AliasLabel.tkname..'     -sticky "e"');
  tkeval('grid configure '..AliasView.tkname..'      -columnspan 2 -sticky "ew" -padx 2');
  tkeval('grid configure '..AddressLabel.tkname..'   -sticky "e"');
  tkeval('grid configure '..AddressView.tkname..'    -columnspan 2 -sticky "ew" -padx 2 -pady 2');

--**** provide an explicit method to terminate this program! ****

  MainWindow:protocol("WM_DELETE_WINDOW", "print('done...'); tkexit()");