/**
  PriceChannel-LowHigh.mq4
  Copyright © 2008, Balidev.com.
  Developed by Balidev.com Software Development http://www.balidev.com
  
  PriceChannel-LowHigh:
     The PriceChannel-LowHigh indicator is a simple indicator showing the 
     lowest/highest value for a certain period.          
     Using this approach this indicator will construct an envlope
     base on low/max value for certain period.     
     The famous Turtle Trading System uses this simple indicator.

  Revision History  
  v.0.1   2008-01-03   Yogi Triana   - Initial Coding

**/

#property copyright "PriceChannel-LowHigh Copyright © 2008, Balidev.com Software Development."
#property link      "http://www.balidev.com"

#property indicator_chart_window
#property indicator_buffers 2
#property indicator_color1 Yellow
#property indicator_color2 Magenta

//---- indicator parameters
extern int    ChannelPeriod = 14;
extern int    ChannelShift  = 0;

//---- buffers
double UpperBuffer[];
double LowerBuffer[];


int init() {

   //---- indicators
   SetIndexStyle(0, DRAW_LINE, STYLE_DOT);
   SetIndexBuffer(0, UpperBuffer);
   SetIndexStyle(1, DRAW_LINE, STYLE_DOT);
   SetIndexBuffer(1, LowerBuffer);

   //----
   SetIndexDrawBegin(0, ChannelPeriod + ChannelShift);
   SetIndexDrawBegin(1, ChannelPeriod + ChannelShift);

   //----
   return(0);
}


int start() {
   int    i, k, counted_bars = IndicatorCounted();
   double highChannel;
   double lowChannel;
   
   if( Bars <= ChannelPeriod ) {
      // in case the is not enough bar for calculation, just return
      return(0);
   }

   if(counted_bars < 1) {
      for( i = 1; i <= ChannelPeriod; i++) {
         UpperBuffer[Bars-i] = EMPTY_VALUE;
         LowerBuffer[Bars-i] = EMPTY_VALUE;
      }
   }
   
   
   int limit = Bars - counted_bars;   
   if (counted_bars > 0) {
      limit++;
   }
  
   int start = Bars - ChannelPeriod + 1;
   for(i = start; i >= 0; i--) {
      int startShifted = i + ChannelShift;
      lowChannel = Low[startShifted];
      highChannel = High[startShifted];
      for (k = 0 ; k <= ChannelPeriod; k++) {
         int shiftedCalc = startShifted + k;
         if (Low[shiftedCalc] < lowChannel) {
            lowChannel = Low[shiftedCalc];
         }
         if (High[shiftedCalc] > highChannel) {
            highChannel = High[shiftedCalc];
         }
      }
      UpperBuffer[i] = highChannel;
      LowerBuffer[i] = lowChannel;
   }
   return(0);
}