I need to modify an indicator

Rules:

• You need to get P1 and P2 based on the indicator Bollinger Bands middle signal.
• 447 is a fixed number.
• The indicator with the Bollinger bands already is integrated to the indicator.
• You need to return a value calculated with the math bellow.
• I need to be able to read this value from a EA.
• I will provide the Indicator to be modified.
• The P1 should be 2 candles behind the P2 in M5 period.

The math:

The final code will be something like this:

      // Trend Calculation

      if(BBMiddleBuffer[i - 2]!=EMPTY_VALUE) {

         double p1 = BBMiddleBuffer[i - 2];

         double p2 = BBMiddleBuffer[i];

         int size = ArraySize(TrendBuffer);

         ArrayResize(TrendBuffer,size+1);

         TrendBuffer[size] = NormalizeDouble((p2 - p1) / 447, _Digits);

      }