#include "StandardLabels.C"

void baseline_noise_test(void)
{
	TRandom rnd(time(NULL));
	
	double noise_rate = 1.0; // GHz
	double noise_amplitude_sigma = 1.0; // mV
	double max_ramp_rate = 1.0/0.5; // mV/ns
	
	double t_width = 130.0; // ns

	// Start off at t=0 and randomly choose a time difference
	// to the next point assuming an exponential time structure
	// until we get past the end of the time window.
	double t = 0.0;
	vector<double> times;
	vector<double> amps;
	times.push_back(0); // add first point as 0 amplitude
	amps.push_back(0.0);
	do{
		double s = rnd.Rndm();
		double delta_t = -1.0/noise_rate * log(1.0-s);
		t += delta_t;
		if(t<t_width){
			double last_t = times[amps.size()-1];
			double last_amp = amps[amps.size()-1];

			double A = rnd.Gaus(0.0, noise_amplitude_sigma);
			
			// Calculate rise time and check that it is not too steep
			double ramp_rate = (A-last_amp)/(t - last_t);
			if(fabs(ramp_rate) <= max_ramp_rate){
				times.push_back(t);
				amps.push_back(A);
			}else{
				// Ramp rate is too high. Discard this time
				// and try again next iteration
				t -= delta_t;
			}
		}
		
	}while(t<t_width);
	times.push_back(t_width); // add last point as 0 amplitude
	amps.push_back(0.0);
	
	cout<<"Npoints: "<<times.size()<<endl;

	TSpline3 *spline = new TSpline3("E-noise", &times[0], &amps[0], times.size());
	
	TCanvas *c1 = new TCanvas("c1", "", 1400, 700);
	c1->SetGrid();
	c1->SetTicks();
	
	TH2D *axes = new TH2D("axes", "Simulated electronic noise", 100, 0.0, t_width, 100, -10.0, 10.0);
	axes->SetStats(0);
	axes->SetXTitle("Time (ns)");
	axes->SetYTitle("Amplitude (mV)");
	axes->Draw();
	
	spline->SetLineColor(kRed);
	spline->Draw("same");
	
	TGraph *graph = new TGraph(times.size(), &times[0], &amps[0]);
	graph->SetMarkerStyle(7);
	graph->SetMarkerSize(0.75);
	graph->SetMarkerColor(kBlack);
	graph->Draw("Psame");
	
	char lab[256];
	sprintf(lab, "1/#tau:%3.1fGHz    #sigma:%3.1fmV    max ramp rate:%3.1fmV/ns", noise_rate, noise_amplitude_sigma, max_ramp_rate);
	StandardLabels(axes,  lab);
	
	c1->SaveAs("baseline_noise_test.png");
	c1->SaveAs("baseline_noise_test.pdf");
}