//+------------------------------------------------------------------+
//|                                                       BOP_v1.mq4 |
//|                           Copyright © 2016, TrendLaboratory Ltd. |
//|            http://finance.groups.yahoo.com/group/TrendLaboratory |
//|                                   E-mail: igorad2003@yahoo.co.uk |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2016, TrendLaboratory Ltd."
#property link      "http://finance.groups.yahoo.com/group/TrendLaboratory"

#property indicator_separate_window
#property indicator_buffers   2
#property indicator_color1    LightBlue
#property indicator_width1    2 
#property indicator_color2    Tomato
#property indicator_width2    2 
//---- input parameters
extern int       PreSmooth =  1;
extern int       Smooth    = 14;
extern int       MA_Mode   =  0; // Mode of MA

//---- buffers
double Up[];
double Dn[];
double BOP[];
double sBOP[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
{
//---- indicators
   IndicatorBuffers(4);
   SetIndexStyle(0,DRAW_HISTOGRAM);
   SetIndexBuffer(0,Up);
   SetIndexStyle(1,DRAW_HISTOGRAM);
   SetIndexBuffer(1,Dn);
   SetIndexBuffer(2,BOP);
   SetIndexBuffer(3,sBOP);
//---- name for DataWindow and indicator subwindow label
   string short_name="Balance of Power ("+PreSmooth+","+Smooth+","+MA_Mode+")";
   IndicatorShortName(short_name);
   SetIndexLabel(0,"Up");
   SetIndexLabel(1,"Down");

//----
   SetIndexDrawBegin(0,PreSmooth + Smooth);
   SetIndexDrawBegin(1,PreSmooth + Smooth);  
   return(0);
}

//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
  {
   int      shift, limit, counted_bars=IndicatorCounted();
   
//---- 
   if ( counted_bars < 0 ) return(-1);
   if ( counted_bars ==0 ) limit=Bars-PreSmooth-Smooth-1;
   
   if ( counted_bars < 1 ) 
   for(int i=1;i<PreSmooth+Smooth;i++) 
   {Up[Bars-i]=0; Dn[Bars-i]=0;}     
      
   if(counted_bars>0) limit=Bars-counted_bars;
   limit--;
   
   for( shift=limit; shift>=0; shift--)
   {
   double mClose = iMA(NULL,0,PreSmooth,0,MA_Mode,PRICE_CLOSE,shift);
   double mOpen  = iMA(NULL,0,PreSmooth,0,MA_Mode,PRICE_OPEN,shift);
   double mHigh = iMA(NULL,0,PreSmooth,0,MA_Mode,PRICE_HIGH,shift);
   double mLow  = iMA(NULL,0,PreSmooth,0,MA_Mode,PRICE_LOW,shift);
   
      if ((mHigh-mLow)!=0)
      BOP[shift] = (mClose - mOpen)/(mHigh-mLow); 
      else
      BOP[shift] = 0;
   }
   
   for( shift=limit; shift>=0; shift--)
   {
   sBOP[shift] = iMAOnArray(BOP,0,Smooth,0,MA_Mode,shift);   
   
      if (sBOP[shift] >= sBOP[shift+1]) {Up[shift] = sBOP[shift]; Dn[shift] = 0;}
      else 
      if (sBOP[shift] < sBOP[shift+1]) {Dn[shift] = sBOP[shift]; Up[shift] = 0;}        
   }   
//----
   return(0);
  }
//+------------------------------------------------------------------+