//+------------------------------------------------------------------+
//|                                          Gann high-low activator |
//|                                                                  |
//+------------------------------------------------------------------+
#property copyright "www.forex-station.com"
#property link      "www.forex-station.com"

#property indicator_chart_window
#property indicator_buffers 3
#property indicator_color1  Lime
#property indicator_color2  Magenta
#property indicator_color3  Yellow
#property indicator_width1  2
#property indicator_width2  2
#property indicator_width3  2

extern string TimeFrame       = "Current time frame";
extern int    Lb              = 10;
extern bool   alertsOn        = false;
extern bool   alertsOnCurrent = true;
extern bool   alertsMessage   = true;
extern bool   alertsSound     = false;
extern bool   alertsEmail     = false;
extern bool   Interpolate     = true;
extern int    MaxBars         = 1000; // Add this line to define the maximum number of bars to process

double gup[];
double gdna[];
double gdnb[];
double trend[];

int    timeFrame;
string indicatorFileName;
bool   returnBars;
bool   calculateValue;

int init()
{
   for (int i=0; i<indicator_buffers; i++) SetIndexStyle(i,DRAW_LINE);
   IndicatorBuffers(4);
   SetIndexBuffer(0,gup);  SetIndexDrawBegin(0,Lb+1);
   SetIndexBuffer(1,gdna); SetIndexDrawBegin(1,Lb+1);
   SetIndexBuffer(2,gdnb); SetIndexDrawBegin(2,Lb+1);
   SetIndexBuffer(3,trend);
   
   indicatorFileName = WindowExpertName();
   calculateValue    = (TimeFrame=="calculateValue"); if (calculateValue) return(0);
   returnBars        = (TimeFrame=="returnBars");     if (returnBars)     return(0);
   timeFrame         = stringToTimeFrame(TimeFrame);
   
   IndicatorShortName(timeFrameToString(timeFrame)+" Gann high/low activator ("+Lb+")");
         
   return(0);
}

int start()
{
   int counted_bars=IndicatorCounted();
   int i,limit;

   if(counted_bars<0) return(-1);
   if(counted_bars>0) counted_bars--;
   limit = MathMin(Bars-counted_bars,Bars-1);
   
   // Apply the MaxBars limit
   limit = MathMin(limit, MaxBars);

   if (returnBars) { gup[0] = limit+1; return(0); }

   if (calculateValue || timeFrame == Period())
   {
      if (!calculateValue && trend[limit]==-1) CleanPoint(limit,gdna,gdnb);
      for(i=limit;i>=0;i--)
      {
         gdna[i]  = EMPTY_VALUE;
         gdnb[i]  = EMPTY_VALUE;
         trend[i] = trend[i+1];
         if(Close[i]>iMA(Symbol(),0,Lb,0,MODE_SMA,PRICE_HIGH,i+1)) trend[i] =  1;
         if(Close[i]<iMA(Symbol(),0,Lb,0,MODE_SMA,PRICE_LOW,i+1))  trend[i] = -1;
      
         if(trend[i] == -1)
            gup[i] = iMA(Symbol(),0,Lb,0,MODE_SMA,PRICE_HIGH,i+1);
         else  
            gup[i] = iMA(Symbol(),0,Lb,0,MODE_SMA,PRICE_LOW,i+1);
         if (!calculateValue && trend[i]==-1) PlotPoint(i,gdna,gdnb,gup);
      }
      manageAlerts();
      return(0);
   }      

   limit = MathMax(limit,MathMin(Bars-1,iCustom(NULL,timeFrame,indicatorFileName,"returnBars",0,0)*timeFrame/Period()));
   if (trend[limit]==-1) CleanPoint(limit,gdna,gdnb);
   for(i=limit; i>=0; i--)
   {
      int y = iBarShift(NULL,timeFrame,Time[i]);
      gdna[i]  = EMPTY_VALUE;
      gdnb[i]  = EMPTY_VALUE;
      gup[i]   = iCustom(NULL,timeFrame,indicatorFileName,"calculateValue",Lb,0,y);
      trend[i] = iCustom(NULL,timeFrame,indicatorFileName,"calculateValue",Lb,3,y);
            
      if (timeFrame <= Period() || y==iBarShift(NULL,timeFrame,Time[i-1])) continue;
      if (!Interpolate) continue;

      datetime time = iTime(NULL,timeFrame,y);
      for(int n = 1; i+n < Bars && Time[i+n] >= time; n++) continue;	
      for(int k = 1; k < n; k++)
         gup[i+k] = gup[i] + (gup[i+n]-gup[i])*k/n;
   }
   for (i=limit;i>=0;i--) if (trend[i]==-1) PlotPoint(i,gdna,gdnb,gup);

   manageAlerts();
   return(0);
}

void manageAlerts()
{
   if (!calculateValue && alertsOn)
   {
      int whichBar;
      if (alertsOnCurrent)
         whichBar = 0;
      else     
         whichBar = 1; 
      whichBar = iBarShift(NULL,0,iTime(NULL,timeFrame,whichBar));
      if (trend[whichBar] != trend[whichBar+1])
      {
         if (trend[whichBar] == 1) doAlert(whichBar,"up");
         if (trend[whichBar] ==-1) doAlert(whichBar,"down");
      }         
   }
}   

void doAlert(int forBar, string doWhat)
{
   static string   previousAlert="nothing";
   static datetime previousTime;
   string message;
   
   if (previousAlert != doWhat || previousTime != Time[forBar]) {
      previousAlert  = doWhat;
      previousTime   = Time[forBar];

      message =  StringConcatenate(Symbol()," at ",TimeToStr(TimeLocal(),TIME_SECONDS)," Gann HL activator trend changed to ",doWhat);
      if (alertsMessage) Alert(message);
      if (alertsEmail)   SendMail(StringConcatenate(Symbol(),"Gann HL "),message);
      if (alertsSound)   PlaySound("alert2.wav");
   }
}

string sTfTable[] = {"M1","M5","M15","M30","H1","H4","D1","W1","MN"};
int    iTfTable[] = {1,5,15,30,60,240,1440,10080,43200};

int stringToTimeFrame(string tfs)
{
   tfs = stringUpperCase(tfs);
   for (int i=ArraySize(iTfTable)-1; i>=0; i--)
      if (tfs==sTfTable[i] || tfs==""+iTfTable[i]) return(MathMax(iTfTable[i],Period()));
   return(Period());
}

string timeFrameToString(int tf)
{
   for (int i=ArraySize(iTfTable)-1; i>=0; i--) 
      if (tf==iTfTable[i]) return(sTfTable[i]);
   return("");
}

string stringUpperCase(string str)
{
   string s = str;

   for (int length=StringLen(str)-1; length>=0; length--)
   {
      int tchar = StringGetChar(s, length);
      if((tchar > 96 && tchar < 123) || (tchar > 223 && tchar < 256))
         s = StringSetChar(s, length, tchar - 32);
      else if(tchar > -33 && tchar < 0)
         s = StringSetChar(s, length, tchar + 224);
   }
   return(s);
}

void CleanPoint(int i,double& first[],double& second[])
{
   if ((second[i]  != EMPTY_VALUE) && (second[i+1] != EMPTY_VALUE))
      second[i+1] = EMPTY_VALUE;
   else if ((first[i] != EMPTY_VALUE) && (first[i+1] != EMPTY_VALUE) && (first[i+2] == EMPTY_VALUE))
      first[i+1] = EMPTY_VALUE;
}

void PlotPoint(int i,double& first[],double& second[],double& from[])
{
   if (first[i+1] == EMPTY_VALUE)
   {
      if (first[i+2] == EMPTY_VALUE) {
         first[i]   = from[i];
         first[i+1] = from[i+1];
         second[i]  = EMPTY_VALUE;
      }
      else {
         second[i]   =  from[i];
         second[i+1] =  from[i+1];
         first[i]    = EMPTY_VALUE;
      }
   }
   else
   {
      first[i]  = from[i];
      second[i] = EMPTY_VALUE;
   }
}