// http://www.cppreference.com/
// http://cplusplus.com/
// http://root.cern.ch/root/html/ClassIndex.html
// http://root.cern.ch/root/html/tutorials/

#include <vector>
#include <string>

#include "TString.h"
#include "TFile.h"
#include "TH1F.h"
#include "TH2F.h"
#include "TCanvas.h"
#include "TF1.h"
#include "TH1D.h"
#include "TProfile.h"
#include "TStyle.h"
#include "TRandom3.h"

double sqr(double in) {
    return in * in;
}

void cplusplusandrootintro() {
    // some C/C++ variable types
    int integer_number = 42;
    printf("integer_number = %d\n", integer_number);
    
    size_t size_number = 10;
    printf("size_number = %lu\n", size_number);
    
    float float_number = 3.1415926535;
    printf("float_number = %f\n", float_number);

    double double_number = 2.718281828459045235;
    printf("double_number = %e\n", double_number);

    std::string some_text = "I'm a string!";
    printf("some_text = %s\n", some_text.c_str());
    
    // create a vector of length 10, with all values 42
    std::vector< int > vec_of_ints(10, 42);
    printf("vec_of_ints: length = %lu, first element = %d\n", vec_of_ints.size(), vec_of_ints.at(0));

    // create a vector of length 10, with all values roughly pi
    std::vector< float > vec_of_floats(5, 3.1415926535);
    printf("vec_of_floats: length = %lu, last element = %g\n", vec_of_floats.size(), vec_of_floats.at(4));
    
    printf("- - - - - - -\n");
    
    std::vector< std::vector< double > > twodim_vec;
    twodim_vec.push_back(std::vector< double >(4, 2.718281828459045235));
    twodim_vec.push_back(std::vector< double >(3, 3.1415926535));
    printf("twodim_vec: length = %lu\n", twodim_vec.size());
    printf("twodim_vec: length of first entry = %lu\n", twodim_vec.at(0).size());
    printf("twodim_vec: length of second entry = %lu\n", twodim_vec.at(1).size());
    printf("twodim_vec: element 0,1 = %f\n", twodim_vec.at(0).at(1));

    printf("- - - - - - -\n");
    
    // short excure into pointers (we will need it in ROOT at some point)
    int num = 42;
    int *p_num = &num;
    printf("num = %d, address of num = %d\n", num, &num);
    printf("p_num = %d, value of pnum = %d\n", p_num, *p_num);
    *p_num -= 1;
    printf("num = %d, address of num = %d\n", num, &num);
    printf("p_num = %d, value of pnum = %d\n", p_num, *p_num);

    printf("- - - - - - -\n");
    
    // some ROOT equivalents
    Int_t ROOT_integer_number = integer_number;
    Float_t ROOT_float_number = float_number;
    Double_t ROOT_double_number = double_number;
    TString ROOT_string = some_text;
    
    // they can be mixed, e.g.
    std::vector< TString > vec_of_tstrings(11, "test");
    
    // structure your code
    if (ROOT_integer_number == 42) {
        printf("ROOT_integer_number = %d\n", ROOT_integer_number);
    }
    
    if (ROOT_double_number == 0. || ROOT_float_number == 0.) {
        printf("this will probably not be written to the screen");
    } else if (1 == 2) {
    } else {
        printf("ROOT_double_number = %f\n", ROOT_double_number);
    }
    
    printf("- - - - - - -\n");
    
    for (size_t i = 0; i < vec_of_ints.size(); ++i) {
        printf("vec_of_ints.at(%lu) = %d\n", i, vec_of_ints.at(i));
        vec_of_ints.at(i) += sqr(i);
    }
    
    printf("- - - - - - -\n");
    
    int j = vec_of_ints.size() - 1;
    while (j >= 0) {
        printf("vec_of_ints.at(%d) = %d\n", j, vec_of_ints.at(j));
        --j;
    }
    
    printf("- - - - - - -\n");

    TCanvas *canvas = new TCanvas("canvas", "some title", 0, 0, 1000, 800);
    canvas->Divide(4, 3);

    TH1F *hist1 = new TH1F("hist1", "title;x-axis;y-axis", 100, -.5, 99.5);
    for (size_t i = 0; i < vec_of_ints.size(); ++i) {
        hist1->Fill(vec_of_ints.at(i) - 42);
    }

    canvas->cd(1);
    hist1->Draw();

    TFile *file1 = new TFile("cplusplusandrootintro.root", "recreate");
    TH1F *hist2 = new TH1F("hist2", "title;x-axis;y-axis", 10, -.5, 9.5);
    for (int k = 0; k < 10; ++k) {
        hist2->Fill(k, k);
    }
    file1->Write();
    canvas->cd(2);
    hist2->Draw();
    file1->Close();
    
    TFile *file2 = new TFile("cplusplusandrootintro.root", "update");
    file2->ls();
    hist1->Write();
    file2->Close();
    
    TFile file3("cplusplusandrootintro.root", "read");
    file3.ls();
    hist2 = (TH1F*)file3.Get("hist2");
    canvas->cd(3);
    hist1->Draw();
    canvas->cd(4);
    hist2->Draw();
    canvas->Update();
    canvas->SaveAs("cplusplusandrootintro.png");
    std::getchar();
    file3.Close();

    gStyle->SetOptStat(1111);
    gStyle->SetOptFit(1111);
    gRandom = new TRandom3();
    
    TF1 *gauss = new TF1("gauss", "gaus");
    gauss->SetParameters(10, 1, 2);
    TH1F *hist3 = new TH1F("hist3", "title;x-axis;y-axis", 100, -10., 10.);
    hist3->FillRandom("gauss", 10000);
    canvas->cd(4);
    hist3->Draw();
    hist3->Fit(gauss);
    
    TH2F *hist4 = new TH2F("hist4", "title;x-axis;y-axis;z-axis", 20, -10., 10., 20, 0., 1.);
    hist4->FillRandom("gauss", 10000);
    canvas->cd(5);
    hist4->Draw();
    canvas->cd(6);
    hist4->Draw("box");
    canvas->cd(7);
    hist4->Draw("colz");
    canvas->cd(8);
    hist4->Draw("lego");
    canvas->cd(9);
    TProfile *profile = hist4->ProfileX("_pfx");
    profile->Draw();
    canvas->cd(10);
    TH1D *projection = hist4->ProjectionX("_pjx", 1 ,1);
    projection->Draw();
    
    TH1F *hist5 = new TH1F("hist5", "title;x-axis;y-axis", 100, -10., 10.);
    for (int k = 0; k < 10000; ++k) {
        hist5->Fill(projection->GetRandom());
    }
    canvas->cd(11);
    hist5->Draw();
}