#include <iostream>
#include <fstream>
#include "TGraph2D.h"
#include "TCanvas.h"
//#include "TFitFunc.h"
#include "TFitResult.h"

void FitMuonTrajectory(const char* filename) {
    // Open the file
    std::ifstream infile("outputevents_xyz.txt");
    if (!infile) {
        std::cerr << "Error opening file: " << filename << std::endl;
        return;
    }
    
    // Arrays to store coordinates
    double x[3], y[3], z[3];
    
    // Read coordinates from file
    for (int i = 0; i < 3; ++i) {
        infile >> x[i] >> y[i] >> z[i];
    }
    
    // Close the file
    infile.close();
    
    // Create a TGraph2D to hold the points
    TGraph2D *graph = new TGraph2D(3, x, y, z);
    graph->SetMarkerStyle(20);
    graph->SetMarkerSize(1.5);
    
   // Create a TFitFunc to fit a straight line (z = a*x + b*y + c)
    TF1  *fit = new TF1("fitFunc", "[0] + [1]*x + [2]*y",-100, 100);
    
    // Fit the function to the graph
    TFitResultPtr fitResult = graph->Fit(fitFunc, "Q");
    
    // Check if the fit converged successfully
    if (fitResult.Get() != nullptr && fitResult->IsValid()) {
        // Print fit results
        std::cout << "Fit parameters: intercept = " << fitFunc->GetParameter(0)
                  << ", slope_x = " << fitFunc->GetParameter(1)
                  << ", slope_y = " << fitFunc->GetParameter(2) << std::endl;
    } else {
        std::cerr << "Fit failed or did not converge!" << std::endl;
    }*/
    
    // Draw the graph and the fit
    TCanvas *canvas = new TCanvas("canvas", "Muon Trajectory Fit", 800, 600);
    graph->Draw("P");
    fitFunc->Draw("same");
    canvas->Draw();
}