#include <stdio.h>
#include <iostream>
#include "TFile.h"
#include "TH1D.h"



int CollectHist (
		TH1D *hist1d_input,
		int ncummulative,
		string name_hist,
		string path_input)
{
	TH1::AddDirectory(kFALSE);
	TFile *file_input = new TFile (path_input.data(), "read");

	TH1D *hist1d_tmp = (TH1D*)file_input -> Get (name_hist.data());

	if (ncummulative<=0)
	{
		hist1d_input = (TH1D*)hist1d_tmp -> Clone();
	}
	else
	{
		hist1d_input -> Add (hist1d_tmp);
	}

	file_input -> Close();
	delete hist1d_tmp;
	delete file_input;

	printf ( "  |   |-- Integral before exist: %.2f\n", hist1d_input->Integral() );

	return 1;
}


void example ()
{
	TH1::AddDirectory(kFALSE);

	TH1D *hist;
	int ncum = 0;

	string list_file[3] =
	{
		"file1.root",
		"file2.root",
		"file3.root"
	};

	printf (" [+] Read files\n");

	for (int i=0; i<3; i++)
	{
		printf ("  |-- File number %d\n", i+1);
		int stt = CollectHist (
				hist,
				ncum,
				"histname",
				list_file[i]);

		printf ( "  |   |-- Integral after exist: %.2f\n", hist->Integral() );
		ncum += stt;
	}

	printf (" [+] Accumulated histogram from %d files\n", ncum);

	TCanvas *canvas = new TCanvas ("canvas", "", 600, 600);
	canvas -> cd();

	hist -> SetLineColor (kOrange);
	hist -> SetLineWidth (2);
	hist -> Draw ("hist");

	canvas -> SaveAs ("accumulatedhistogram.png");

	delete canvas;
	delete hist;
}