#include <TFile.h>
#include <TKey.h>
#include <TDirectory.h>
#include <TSystem.h>
#include <TH1.h>

#include <iostream>
#include <vector>
#include <string>
#include <iomanip> // for setw

void AddDir(TDirectory* src, TDirectory* dest)
{
    TIter next(src->GetListOfKeys());
    TKey* key;

    while ((key = (TKey*)next())) {
        TObject* obj = key->ReadObj();

        if (obj->InheritsFrom("TDirectory")) {
            TDirectory* srcSub = (TDirectory*)obj;
            TDirectory* destSub =
                dest->GetDirectory(srcSub->GetName());

            if (!destSub)
                destSub = dest->mkdir(srcSub->GetName());

            AddDir(srcSub, destSub);
        }
        else if (obj->InheritsFrom("TH1")) {
            TH1* h = (TH1*)obj;
            TH1* hsum =
                (TH1*)dest->Get(h->GetName());

            if (!hsum) {
                hsum = (TH1*)h->Clone();
                hsum->SetDirectory(dest);
                hsum->Sumw2(kTRUE);
            } else {
                hsum->Add(h);
            }
            hsum->SetOption("HIST");
        }
    }
}

// Simple text-based progress bar
void printProgress(int current, int total, int barWidth = 50)
{
    float progress = float(current) / total;
    int pos = int(barWidth * progress);

    std::cout << "[";
    for (int i = 0; i < barWidth; ++i) {
        if (i < pos) std::cout << "=";
        else if (i == pos) std::cout << ">";
        else std::cout << " ";
    }
    std::cout << "] " << int(progress * 100.0) << "%\r";
    std::cout.flush();
}

int main(int argc, char** argv)
{
    if (argc != 3) {
        std::cerr << "Usage: " << argv[0]
                  << " <directory> <output_file>\n";
        return 1;
    }

    TString dir = argv[1];
    TString outName = argv[2];  // <-- now from command-line

    void* dirp = gSystem->OpenDirectory(dir);
    if (!dirp) {
        std::cerr << "Cannot open directory "
                  << dir << std::endl;
        return 1;
    }

    // Gather all ROOT files in a vector
    std::vector<TString> files;
    const char* entry;
    while ((entry = gSystem->GetDirEntry(dirp))) {
        TString fname(entry);
        if (!fname.EndsWith(".root")) continue;
        if (fname == outName) continue; // avoid overwriting output
        files.push_back(fname);
    }
    gSystem->FreeDirectory(dirp);

    if (files.empty()) {
        std::cerr << "No ROOT files found in directory." << std::endl;
        return 1;
    }

    TFile* fout = new TFile(dir + "/" + outName, "RECREATE");

    // Loop over files with progress bar
    int totalFiles = files.size();
    for (int i = 0; i < totalFiles; ++i) {
        TString full = dir + "/" + files[i];
        TFile f(full, "READ");
        if (!f.IsZombie())
            AddDir(&f, fout);
        f.Close();

        printProgress(i + 1, totalFiles);
    }

    fout->Write();
    fout->Close();

    std::cout << std::endl << "Output written to " << dir + "/" + outName << std::endl;
    return 0;
}