#property indicator_chart_window
#property indicator_buffers 0

#import "user32.dll"
  int PostMessageA(int hWnd,int Msg,int wParam,int lParam);
#import

#define WM_COMMAND 0x0111

#define LB_OFFSET -32
#define BEGIN_OFFSET 148

#define REFRESH_CODE 33324

double open, low, high, close;
int handle, PrevTime;
string SymbolName;

void GetSymbolName()
{
  SymbolName = StringSubstr(Symbol(), 3, 3) + StringSubstr(Symbol(), 0, 3);
  
  return;
}

bool GetBarPrices( int Pos )
{  
  open = 1 / Open[Pos];
  high = 1 / Low[Pos];
  low = 1 / High[Pos];
  close = 1 / Close[Pos];
  
  return;
}

void WriteBar( int STime, double SOpen, double SHigh, double SLow, double SClose, double SVolume )
{
  FileWriteInteger(handle, STime);
  FileWriteDouble(handle, SOpen);
  FileWriteDouble(handle, SLow);
  FileWriteDouble(handle, SHigh);
  FileWriteDouble(handle, SClose);
  FileWriteDouble(handle, SVolume);
  
  FileFlush(handle);
  
  return;
}

void WriteBars( int Pos )
{
  Pos--;
  
  while (Pos >= 0)
  {
    GetBarPrices(Pos);
    WriteBar(Time[Pos], open, high, low, close, Volume[Pos]);
    Pos--;  
  }
  
  return;
}

void ModifyLastBar( int Pos )
{
  GetBarPrices(Pos);
  
  FileSeek(handle, LB_OFFSET, SEEK_CUR);

  FileWriteDouble(handle, low);
  FileWriteDouble(handle, high);
  FileWriteDouble(handle, close);
  FileWriteDouble(handle, Volume[Pos]);
  
  FileFlush(handle);
  
  return;
}

void CreateHandle()
{
  string FileName;
  int Tmp[15], TmpTime;

  GetSymbolName();
  FileName = SymbolName + Period() + ".hst";
  handle = FileOpenHistory(FileName, FILE_BIN|FILE_WRITE);
  
  FileWriteInteger(handle, 400);
  FileWriteString(handle, "Created by " + WindowExpertName(), 64);
  FileWriteString(handle, SymbolName, 12);
  FileWriteInteger(handle, Period());
  FileWriteInteger(handle, Digits);
  FileWriteArray(handle, Tmp, 0, 15);
  
  return;
}

void RefreshChart()
{
  int hwnd = WindowHandle(SymbolName, Period());

  PostMessageA(hwnd, WM_COMMAND, REFRESH_CODE, 0);
    
  return;
}

void init()
{  
  CreateHandle();
  
  PrevTime = Time[0];

  return;
}

void deinit()
{
  FileClose(handle);
  
  return;
}

void start()
{
  static int PrevBars = 0;
  static int Pos;
  
  if (PrevTime != Time[0])
  {
    Pos = iBarShift(Symbol(), Period(), PrevTime);
    
    ModifyLastBar(Pos);
    WriteBars(Pos);
    
    PrevTime = Time[0];
    PrevBars = Bars;
  }
  else
  {
    if (PrevBars != Bars)
    {
      FileSeek(handle, BEGIN_OFFSET, SEEK_SET);
      
      WriteBars(Bars);
      
      PrevBars = Bars;
    }
    else
      ModifyLastBar(0);
  }

  RefreshChart();        

  return;
}