{
   System independent system interface for win32/win64

   Copyright (c) 2000 by Pierre Muller

   See the file COPYING.FPC, included in this distribution,
   for details about the copyright.

   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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
}

uses
   windows,dos,winevent;

var
   ChangeSystemEvents : TCriticalSection;
Const
  SystemEventActive : Boolean = false;

procedure SystemEventHandler(var ir:INPUT_RECORD);

  var
     e : TSystemEvent;

  begin
  { WINDOW_BUFFER_SIZE_EVENT is triggered by buffer size changes
    but we are interested in console size changes, thus its handled below
    in PollSystemEvent }
     if (ir.EventType in [FOCUS_EVENT{,WINDOW_BUFFER_SIZE_EVENT}]) then
       begin
          EnterCriticalSection(ChangeSystemEvents);
          if (ir.EventType=FOCUS_EVENT) then
            begin
              if ir.Event.FocusEvent.bSetFocus then
                e.typ:=SysSetFocus
              else
                e.typ:=SysReleaseFocus;
            end
          else
            begin
              e.typ:=SysResize;
              e.x:=ir.Event.WindowBufferSizeEvent.dwSize.x;
              e.y:=ir.Event.WindowBufferSizeEvent.dwSize.y;
            end;
          PutSystemEvent(e);
          LeaveCriticalSection(ChangeSystemEvents);
       end;
  end;


var
  Xsize, YSize : longint;

function HandleConsoleCtrl(typ : dword) : BOOL; stdcall;
var
  SE :   TSystemEvent;
begin
  HandleConsoleCtrl:=false;
  case typ of
    CTRL_CLOSE_EVENT,
    CTRL_LOGOFF_EVENT,
    CTRL_SHUTDOWN_EVENT :
      begin
        SE.typ:=SysClose;
        SE.CloseTyp:=typ;
        PutSystemEvent(SE);
        HandleConsoleCtrl:=true;
      end;
  end;
end;


procedure InitSystemMsg;

var
   mode : dword;
   ConsoleScreenBufferInfo : Console_screen_buffer_info;

begin
  if SystemEventActive then
    exit;
  // enable Window events
  GetConsoleMode(TextRec(Input).Handle,@mode);
  mode:=mode or ENABLE_WINDOW_INPUT;
  SetConsoleMode(TextRec(Input).Handle,mode);
  GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE),
    @ConsoleScreenBufferInfo);
  XSize:=ConsoleScreenBufferInfo.srWindow.right-ConsoleScreenBufferInfo.srWindow.left+1;
  YSize:=ConsoleScreenBufferInfo.srWindow.bottom-ConsoleScreenBufferInfo.srWindow.top+1;
  PendingSystemHead:=@PendingSystemEvent;
  PendingSystemTail:=@PendingSystemEvent;
  PendingSystemEvents:=0;
  FillChar(LastSystemEvent,sizeof(TSystemEvent),0);
  InitializeCriticalSection(ChangeSystemEvents);
  SetResizeEventHandler(@SystemEventHandler);
  SetFocusEventHandler(@SystemEventHandler);
  SetConsoleCtrlHandler(@HandleConsoleCtrl,true);
  SystemEventActive:=true;
end;


procedure DoneSystemMsg;
var
   mode : dword;
begin
  if not SystemEventActive then
    exit;
  // disable System events
  GetConsoleMode(TextRec(Input).Handle,@mode);
  mode:=mode and (not ENABLE_WINDOW_INPUT);
  SetConsoleMode(TextRec(Input).Handle,mode);

  SetResizeEventHandler(nil);
  SetFocusEventHandler(nil);
  DeleteCriticalSection(ChangeSystemEvents);
  SetConsoleCtrlHandler(@HandleConsoleCtrl,false);
  SystemEventActive:=false;
end;



procedure GetSystemEvent(var SystemEvent: TSystemEvent);

var
   b : byte;

begin
  repeat
    EnterCriticalSection(ChangeSystemEvents);
    b:=PendingSystemEvents;
    LeaveCriticalSection(ChangeSystemEvents);
    if b>0 then
      break
    else
      sleep(50);
  until false;
  EnterCriticalSection(ChangeSystemEvents);
  SystemEvent:=PendingSystemHead^;
  inc(PendingSystemHead);
  if longint(PendingSystemHead)=longint(@PendingSystemEvent)+sizeof(PendingSystemEvent) then
   PendingSystemHead:=@PendingSystemEvent;
  dec(PendingSystemEvents);
  LastSystemEvent:=SystemEvent;
  LeaveCriticalSection(ChangeSystemEvents);
end;


function PollSystemEvent(var SystemEvent: TSystemEvent):boolean;
var
   ConsoleScreenBufferInfo : Console_screen_buffer_info;
   NewXSize, NewYSize : longint;
begin
  EnterCriticalSection(ChangeSystemEvents);
  if PendingSystemEvents>0 then
   begin
     SystemEvent:=PendingSystemHead^;
     PollSystemEvent:=true;
   end
  else
   begin
     GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE),
       @ConsoleScreenBufferInfo);
     NewXSize:=ConsoleScreenBufferInfo.srWindow.right-ConsoleScreenBufferInfo.srWindow.left+1;
     NewYSize:=ConsoleScreenBufferInfo.srWindow.bottom-ConsoleScreenBufferInfo.srWindow.top+1;
     if (XSize<>NewXSize) or (YSize<>NewYSize) then
       begin
         SystemEvent.typ:=SysResize;
         SystemEvent.x:=NewXSize;
         SystemEvent.y:=NewYSize;
         PutSystemEvent(SystemEvent);
         XSize:=NewXSize;
         YSize:=NewYSize;
         PollSystemEvent:=true;
       end
     else
       PollSystemEvent:=false;
   end;
  LeaveCriticalSection(ChangeSystemEvents);
end;