Inputs, Parameters, and the Strategy Tester

//+------------------------------------------------------------------+
//| Lesson 5 - Grouped inputs, enum inputs, optimisation             |
//+------------------------------------------------------------------+
#property copyright "Strategist Academy"
#property version   "1.00"

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1
#property indicator_type1   DRAW_LINE
#property indicator_width1  2

input group "Moving average"
input int                Period    = 50;          // Period
input ENUM_APPLIED_PRICE Applied   = PRICE_CLOSE; // Applied price

input group "Display"
input color              LineColor = clrOrange;   // Line colour

double Buffer[];

int OnInit()
{
   if(Period < 2) return(INIT_FAILED);

   SetIndexBuffer(0, Buffer, INDICATOR_DATA);
   PlotIndexSetInteger(0, PLOT_DRAW_BEGIN, Period - 1);
   PlotIndexSetInteger(0, PLOT_LINE_COLOR, 0, LineColor);
   PlotIndexSetString(0, PLOT_LABEL, "MA(" + IntegerToString(Period) + ")");
   IndicatorSetString(INDICATOR_SHORTNAME, "Lesson 5 MA(" + IntegerToString(Period) + ")");
   return(INIT_SUCCEEDED);
}

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(rates_total < Period) return(0);

   // Pick the source array based on the enum input.
   // (Applied price handling is simplified here; built-in iMA does this properly
   //  and is covered in Part 4.)
   int start = (prev_calculated == 0) ? Period - 1 : prev_calculated - 1;
   if(start < Period - 1) start = Period - 1;

   for(int i = start; i < rates_total && !IsStopped(); i++)
   {
      double sum = 0.0;
      for(int k = 0; k < Period; k++)
         sum += close[i - k];
      Buffer[i] = sum / Period;
   }
   return(rates_total);
}