//+------------------------------------------------------------------+
//|                                            L1TrendRandomWalk.mq5 |
//|                             Copyright 2000-2026, MetaQuotes Ltd. |
//|                                              http://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2000-2026, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"
//---
#include <Graphics\Graphic.mqh>
//---
uint32_t       ExtSeed = 1;
//--- buffer
vector<double> ExtBuffer;
double         ExtLastValue = 0.0;
int            ExtHead = 0;
bool           ExtReady = false;
//+------------------------------------------------------------------+
//| Init                                                             |
//+------------------------------------------------------------------+
void BMInit(uint32_t size)
  {
   MathSrand(ExtSeed);
   ExtBuffer.Resize(size);
   ExtLastValue = 0.0;
   for(uint32_t i = 0; i < size; i++)
     {
      ExtLastValue += (MathRand() / 32767.0 - 0.5);
      ExtBuffer[i] = ExtLastValue;
     }
   ExtHead  = 0;
   ExtReady = true;
  }
//+------------------------------------------------------------------+
//| Add N new points                                                 |
//+------------------------------------------------------------------+
void BMNext(int n_points)
  {
   if(!ExtReady)
      return;
   int size = (int)ExtBuffer.Size();
   for(int k=0; k<n_points; k++)
     {
      ExtLastValue += (MathRand() / 32767.0 - 0.5);
      ExtBuffer[ExtHead] = ExtLastValue;
      ExtHead++;
      if(ExtHead >= size)
         ExtHead = 0;
     }
  }
//+------------------------------------------------------------------+
//| Get ordered data                                                 |
//+------------------------------------------------------------------+
bool BMGet(double &out[])
  {
   if(!ExtReady)
      return(false);

   int size = (int)ExtBuffer.Size();

   if(ArrayResize(out, size) != (int)size)
      return(false);

   for(int i = 0; i < size; i++)
     {
      int idx = (ExtHead + i) % size;
      out[i] = ExtBuffer[idx];
     }

   return(true);
  }
//+------------------------------------------------------------------+
//| L1Trend from existing data                                       |
//+------------------------------------------------------------------+
bool L1Trend(double &result[], const double &src[], int size, double lambda)
  {
   vector<double> v;
   v.Resize(size);

   for(int i=0; i<size; i++)
      v[i] = src[i];

   vector<double> vres;
   if(!v.L1TrendFilter(lambda, true, vres))
      return(false);

   if(ArrayResize(result,(int)vres.Size()) != (int)vres.Size())
      return(false);

   for(int i=0; i<(int)vres.Size(); i++)
      result[i]=vres[i];

   return(true);
  }
//+------------------------------------------------------------------+
//| TestRun                                                          |
//+------------------------------------------------------------------+
bool TestRun(int data_count)
  {
//--- init or continue
   if(!ExtReady || ExtBuffer.Size() != data_count)
      BMInit(data_count);
   else
      BMNext(10);   // add new values
//--- graphic
   CGraphic graphic;
   long chart = 0;
   string name = "Random walk";
   if(ObjectFind(chart,name)<0)
      graphic.Create(chart,name,0,0,0,1000,600);
   else
      graphic.Attach(chart,name);
//---
   graphic.BackgroundMain("L1Trend filtering (random walk) with different lambda ");
   graphic.BackgroundMainSize(16);
   graphic.HistoryNameWidth(60);
   graphic.HistoryColor(ColorToARGB(clrGray,255));
   graphic.XAxis().AutoScale(false);
   graphic.XAxis().Min(0);
   graphic.XAxis().Max(data_count);
//--- X
   double x[];
   ArrayResize(x, data_count);
   for(int i=0; i<data_count; i++)
      x[i] = i;
//--- data
   double y[];
   if(!BMGet(y))
      return(false);

   graphic.CurveAdd(x, y, CURVE_LINES, "Data").LinesWidth(1);
//--- filters
   const double lambda_factors[] = {1.0,0.8,0.5,0.2,0.1,0.01,0.001};
   for(int i=0; i<ArraySize(lambda_factors); i++)
     {
      double yt[];
      if(L1Trend(yt, y, data_count, lambda_factors[i]))
         graphic.CurveAdd(x, yt, CURVE_LINES, "λ=" + DoubleToString(lambda_factors[i],4)).LinesWidth(3);
     }
//--- draw
   graphic.CurvePlotAll();
   graphic.Update();
//---
   return(true);
  }
//+------------------------------------------------------------------+
//| OnStart                                                          |
//+------------------------------------------------------------------+
void OnStart()
  {
   for(int n=0; !IsStopped(); n++, Sleep(1))
      TestRun(1000);
  }