Convert MT5 Indicator Code into Expert Advisor (without iCustom)

Looking to convert some indicator code that I have, so that I can fetch the indicator values without using iCustom.

Example:

I want to be able to return the O / H / L / C values for a given bar as well as other indicator values.

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 &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   if(initFailed)
     {
      return(prev_calculated);
     }
   static double source[], RSI[];
   static int SIZE = -1;
   if(SIZE <= rates_total)
     {
      SIZE = ArrayResize(source, rates_total + 500, 2000);
      ArrayResize(RSI, rates_total + 500, 2000);
     }
   const int limit = (prev_calculated > 0) ? prev_calculated - 1 : 0;
//---
   for(int i = limit; i < rates_total && !_StopFlag; i++)
     {
      source[i] = iGetPrice(i_source, open[i], high[i], low[i], close[i]);
      //  standard, or ha smoothed rsi for the line plot and/or histogram
      RSI[i] = f_rsi(source, i_lenRSI, i_mode, i, rates_total, 0);

      //  get OHLC values to use in the plotcandle()
      HA ha = f_rsiHeikinAshi(i_lenHARSI, open, high, low, close, i, rates_total, 1);
      double O = ha.O, H = ha.H, L = ha.L, C = ha.C;

      op[i] = O;
      hi[i] = H;
      lo[i] = L;
      cl[i] = C;
      clr[i] = cl[i] > op[i] ? 0 : 1;

     }
//--- return value of prev_calculated for next call
   return(rates_total);
  }

Deliver Price (pending speed of delivery).

- 4 Hours = $80

- 12 Hours = $60

- 24 Hours = $40

I will share the source code once we discuss more.