Translate indicator parameters to EA. PVT setup.

[Joao Lucas Silva Penido]

Hello guys, this is my first post here, what motivated me was to spend the fourth overnight in a row trying to translate a PVT  (price volume trend) indicator to an EA strategy. When the pvt crosses a moving average up or down.

The indicator I downloaded to be able to get the calculation base was from Metaquotes: https://www.mql5.com/en/code/45 and it goes like this:

int OnCalculate(const int rates_total,const int prev_calculated,
                const datetime &Time[],
                const double &Open[],
                const double &High[],
                const double &Low[],
                const double &Close[],
                const long &TickVolume[],
                const long &Volume[],
                const int &Spread[])
  {
//--- variables
   int pos;
//--- check for bars count
   if(rates_total<2)
      return(0);
//--- start calculation
   pos=prev_calculated-1;
//--- correct position, when it's first iteration
   if(pos<0)
     {
      pos=1;
      ExtPVTBuffer[0]=0.0;
     }
//--- main cycle
   if(InpVolumeType==VOLUME_TICK)
      CalculatePVT(pos,rates_total,Close,TickVolume);
   else
      CalculatePVT(pos,rates_total,Close,Volume);
//---- OnCalculate done. Return new prev_calculated.
   return(rates_total);
  }
//+------------------------------------------------------------------+
//| Calculate PVT by volume argument                                 |
//+------------------------------------------------------------------+
void CalculatePVT(int nPosition,
                  int nRatesCount,
                  const double &ClBuffer[],
                  const long &VolBuffer[])
  {
   if(nPosition<=0) nPosition=1;
//---
   for(int i=nPosition;i<nRatesCount && !IsStopped();i++)
     {
      //--- get some data
      double PrevClose=ClBuffer[i-1];
      //--- calculate PVT value
      if(PrevClose!=0)
         ExtPVTBuffer[i]=((ClBuffer[i]-PrevClose)/PrevClose)*VolBuffer[i]+ExtPVTBuffer[i-1];
      else ExtPVTBuffer[i]=ExtPVTBuffer[i-1];
     }

And I'm having trouble translating the call from Oncalculate, which has the rates_total and prev_calculated parameters. Because in the EA we cannot call this function.

int OnCalculate(const int rates_total,const int prev_calculated,
                const datetime &Time[],
                const double &Open[],
                const double &High[],
                const double &Low[],
                const double &Close[],
                const long &TickVolume[],
                const long &Volume[],
                const int &Spread[])

Hence the idea is to look for a way to translate this code so that the EA runs, and I saw that there is a workaround using iBars for rates_total, which then pulls the number of bars for the period you stipulate. but it was the most I managed to develop =(

I've been programming EAs for 4 months and the learning here is being almost literally based on trial and error, and this is the first time I ask for help here, because I believe that I lack a simple detail that is not yet part of my knowledge.
Cheers!