ZigZag with alerts

//+------------------------------------------------------------------+
//|                                        Custom Moving Average.mq4 |
//|                      Copyright © 2005, MetaQuotes Software Corp. |
//|                                       http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2005, MetaQuotes Software Corp."
#property link      "http://www.metaquotes.net/"

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_color1 Red
//---- indicator parameters
extern int  ExtDepth       = 12;
extern int  ExtDeviation   = 5;
extern int  ExtBackstep    = 3;
extern bool alerts.On      = false;
extern bool alerts.Message = true;
extern bool alerts.Sound   = false;
extern bool alerts.Email   = false;

//---- indicator buffers
double ExtMapBuffer[];
double ExtMapBuffer2[];

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
   IndicatorBuffers(2);
//---- drawing settings
   SetIndexStyle(0,DRAW_SECTION);
//---- indicator buffers mapping
   SetIndexBuffer(0,ExtMapBuffer);
   SetIndexBuffer(1,ExtMapBuffer2);
   SetIndexEmptyValue(0,0.0);
//---- indicator short name
   IndicatorShortName("ZigZag("+ExtDepth+","+ExtDeviation+","+ExtBackstep+")");
//---- initialization done
   return(0);
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
int start()
  {
   int    shift, back,lasthighpos,lastlowpos;
   double val,res;
   double curlow,curhigh,lasthigh,lastlow;

   for(shift=Bars-ExtDepth; shift>=0; shift--)
     {
      val=Low[Lowest(NULL,0,MODE_LOW,ExtDepth,shift)];
      if(val==lastlow) val=0.0;
      else 
        { 
         lastlow=val; 
         if((Low[shift]-val)>(ExtDeviation*Point)) val=0.0;
         else
           {
            for(back=1; back<=ExtBackstep; back++)
              {
               res=ExtMapBuffer[shift+back];
               if((res!=0)&&(res>val)) ExtMapBuffer[shift+back]=0.0; 
              }
           }
        } 
      ExtMapBuffer[shift]=val;
      //--- high
      val=High[Highest(NULL,0,MODE_HIGH,ExtDepth,shift)];
      if(val==lasthigh) val=0.0;
      else 
        {
         lasthigh=val;
         if((val-High[shift])>(ExtDeviation*Point)) val=0.0;
         else
           {
            for(back=1; back<=ExtBackstep; back++)
              {
               res=ExtMapBuffer2[shift+back];
               if((res!=0)&&(res<val)) ExtMapBuffer2[shift+back]=0.0; 
              } 
           }
        }
      ExtMapBuffer2[shift]=val;
     }

   // final cutting 
   lasthigh=-1; lasthighpos=-1;
   lastlow=-1;  lastlowpos=-1;

   for(shift=Bars-ExtDepth; shift>=0; shift--)
     {
      curlow=ExtMapBuffer[shift];
      curhigh=ExtMapBuffer2[shift];
      if((curlow==0)&&(curhigh==0)) continue;
      //---
      if(curhigh!=0)
        {
         if(lasthigh>0) 
           {
            if(lasthigh<curhigh) ExtMapBuffer2[lasthighpos]=0;
            else ExtMapBuffer2[shift]=0;
           }
         //---
         if(lasthigh<curhigh || lasthigh<0)
           {
            lasthigh=curhigh;
            lasthighpos=shift;
           }
         lastlow=-1;
        }
      //----
      if(curlow!=0)
        {
         if(lastlow>0)
           {
            if(lastlow>curlow) ExtMapBuffer[lastlowpos]=0;
            else ExtMapBuffer[shift]=0;
           }
         //---
         if((curlow<lastlow)||(lastlow<0))
           {
            lastlow=curlow;
            lastlowpos=shift;
           } 
         lasthigh=-1;
        }
     }
  
   for(shift=Bars-1; shift>=0; shift--)
     {
      if(shift>=Bars-ExtDepth) ExtMapBuffer[shift]=0.0;
      else
        {
         res=ExtMapBuffer2[shift];
         if(res!=0.0) ExtMapBuffer[shift]=res;
        }
     }

   if (alerts.On)
   {
      bool foundPeak         = false;
      bool foundPreviousPeak = false;
      bool peakIsUp          = false;
      int  peakShift         = 0;
      
      //
      //
      //
      //
      //
      
      for (shift=0; shift<Bars; shift++)
         if (ExtMapBuffer[shift]!=0)
         {
            peakShift = shift;
            foundPeak = true;
            break;
         }
      if (foundPeak)
      {
         shift++;
         for (;shift<Bars;shift++)
         if (ExtMapBuffer[shift]!=0)
         {
            if (ExtMapBuffer[shift]<ExtMapBuffer[peakShift])
               peakIsUp=true;
            break;
         }
      }

      //
      //
      //
      //
      //
            
      if (foundPeak)
      if (peakIsUp)
           doAlert("ZigZag made a new upper peak at "+TimeToStr(Time[peakShift],TIME_DATE|TIME_SECONDS),Time[peakShift]);
      else doAlert("ZigZag made a new lower peak at "+TimeToStr(Time[peakShift],TIME_DATE|TIME_SECONDS),Time[peakShift]);
   }
}

//
//
//
//
//

void doAlert(string doWhat,datetime time)
{
   static string   previousAlert="nothing";
   static datetime previousTime;
   string message;
   
   if (previousAlert != doWhat || previousTime != time) {
       previousAlert  = doWhat;
       previousTime   = time;

       //
       //
       //
       //
       //

       message =  StringConcatenate(Symbol()," at ",TimeToStr(TimeLocal(),TIME_SECONDS)," ZigZag : ",doWhat);
          if (alerts.Message) Alert(message);
          if (alerts.Email)   SendMail("ZigZag : ",message);
          if (alerts.Sound)   PlaySound("alert2.wav");
   }
}