//+------------------------------------------------------------------+
//|                                               RSI_Oscillator.mq5 |
//|                      Copyright 2025, xxxxxxxx                    |
//|                                                                  |
//+------------------------------------------------------------------+
#property copyright "Copyright 2025, xxxxxxxx"
#property link      ""
#property version   "1.00"
#property description "RSI Oscillator (Histogram of RSI vs Signal Line)"

//--- Indicator Window and Plot Properties ---
#property indicator_separate_window
#property indicator_buffers 1
#property indicator_plots   1
#property indicator_type1   DRAW_HISTOGRAM
#property indicator_color1  clrSilver
#property indicator_width1  1
#property indicator_label1  "RSI Oscillator"
#property indicator_level1  0.0
#property indicator_levelstyle STYLE_DOT

//--- Input Parameters ---
input int                 InpPeriodRSI    = 14;
input ENUM_APPLIED_PRICE  InpAppliedPrice = PRICE_CLOSE;
input group               "Signal Line Settings"
input int                 InpPeriodMA     = 14;
input ENUM_MA_METHOD      InpMethod       = MODE_SMA;

//--- Indicator Buffers ---
double    BufferOscillator[];

//--- Global Variables ---
int       g_ExtPeriodRSI, g_ExtPeriodMA;
int       g_handle_rsi;

//+------------------------------------------------------------------+
//| Custom indicator initialization function.                        |
//+------------------------------------------------------------------+
int OnInit()
  {
   g_ExtPeriodRSI = (InpPeriodRSI < 1) ? 1 : InpPeriodRSI;
   g_ExtPeriodMA  = (InpPeriodMA < 1) ? 1 : InpPeriodMA;

   SetIndexBuffer(0, BufferOscillator, INDICATOR_DATA);
   ArraySetAsSeries(BufferOscillator, false);

   int draw_begin = g_ExtPeriodRSI + g_ExtPeriodMA - 1;
   PlotIndexSetInteger(0, PLOT_DRAW_BEGIN, draw_begin);
   IndicatorSetString(INDICATOR_SHORTNAME, StringFormat("RSI Osc(%d,%d)", g_ExtPeriodRSI, g_ExtPeriodMA));
   IndicatorSetInteger(INDICATOR_DIGITS, 2);

   g_handle_rsi = iRSI(_Symbol, _Period, g_ExtPeriodRSI, InpAppliedPrice);
   if(g_handle_rsi == INVALID_HANDLE)
     {
      Print("Error creating iRSI handle.");
      return(INIT_FAILED);
     }
   return(INIT_SUCCEEDED);
  }

//+------------------------------------------------------------------+
//| Custom indicator deinitialization function.                      |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
   IndicatorRelease(g_handle_rsi);
  }

//+------------------------------------------------------------------+
//| RSI Oscillator calculation 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 &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   int start_pos = g_ExtPeriodRSI + g_ExtPeriodMA - 1;
   if(rates_total <= start_pos)
      return(0);

//--- Internal Buffers for calculation ---
   double buffer_rsi[], buffer_signal[];
   ArrayResize(buffer_rsi, rates_total);
   ArrayResize(buffer_signal, rates_total);

//--- STEP 1: Get RSI values
   if(CopyBuffer(g_handle_rsi, 0, 0, rates_total, buffer_rsi) < rates_total)
     {
      Print("Error copying RSI buffer data.");
     }

//--- STEP 2: Calculate the Signal Line (MA of RSI)
   for(int i = start_pos; i < rates_total; i++)
     {
      switch(InpMethod)
        {
         case MODE_EMA:
         case MODE_SMMA:
            if(i == start_pos)
              {
               double sum=0;
               for(int j=0; j<g_ExtPeriodMA; j++)
                  sum+=buffer_rsi[i-j];
               buffer_signal[i] = sum/g_ExtPeriodMA;
              }
            else
              {
               if(InpMethod == MODE_EMA)
                 {
                  double pr=2.0/(g_ExtPeriodMA+1.0);
                  buffer_signal[i] = buffer_rsi[i]*pr + buffer_signal[i-1]*(1.0-pr);
                 }
               else
                  buffer_signal[i] = (buffer_signal[i-1]*(g_ExtPeriodMA-1)+buffer_rsi[i])/g_ExtPeriodMA;
              }
            break;
         case MODE_LWMA:
           {
            double lwma_sum=0, weight_sum=0;
            for(int j=0; j<g_ExtPeriodMA; j++)
              {
               int weight=g_ExtPeriodMA-j;
               lwma_sum+=buffer_rsi[i-j]*weight;
               weight_sum+=weight;
              }
            if(weight_sum>0)
               buffer_signal[i]=lwma_sum/weight_sum;
           }
         break;
         default: // MODE_SMA
           {
            double sum=0;
            for(int j=0; j<g_ExtPeriodMA; j++)
               sum+=buffer_rsi[i-j];
            buffer_signal[i] = sum/g_ExtPeriodMA;
           }
         break;
        }
     }

//--- STEP 3: Calculate the final Oscillator value
   for(int i = start_pos; i < rates_total; i++)
     {
      BufferOscillator[i] = buffer_rsi[i] - buffer_signal[i];
     }

   return(rates_total);
  }
//+------------------------------------------------------------------+
//+------------------------------------------------------------------+