#include "GeometryDescriptor.hh"
#include "G4System.hh"

#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>

int main(int argc, char** argv) {
    int nEvents = 10;
    double energy_GeV = 1.0;

    int seed = -1;
    if (const char* seedEnv = std::getenv("MINICALOSIM_SEED")) {
        try {
            std::size_t pos = 0;
            std::string seedStr(seedEnv);
            int parsed = std::stoi(seedStr, &pos);
            if (pos == seedStr.size()) seed = parsed;
        } catch (const std::exception&) {
            // Not a valid integer; fall back to time-based seed.
        }
    }

    if (argc > 3) {
        std::cerr << "Usage: run_pbwo4 [nEvents] [energy_GeV]" << std::endl;
        return 1;
    }
    if (argc >= 2) {
        try {
            nEvents = std::stoi(argv[1]);
            if (nEvents <= 0) throw std::invalid_argument("must be positive");
        } catch (const std::exception& e) {
            std::cerr << "Invalid nEvents '" << argv[1] << "': " << e.what() << std::endl;
            return 1;
        }
    }
    if (argc == 3) {
        try {
            energy_GeV = std::stod(argv[2]);
            if (energy_GeV <= 0) throw std::invalid_argument("must be positive");
        } catch (const std::exception& e) {
            std::cerr << "Invalid energy_GeV '" << argv[2] << "': " << e.what() << std::endl;
            return 1;
        }
    }

    std::string outfile = "pbwo4_" + std::to_string(nEvents) + "events_hits.root";

    GeometryDescriptor gd;
    gd.addLayer(20.0, "G4_PbWO4", true, 10, 10);

    G4System g4;
    g4.init(gd, seed);
    g4.run_batch(nEvents, {"e-"}, energy_GeV, energy_GeV, outfile);

    std::cout << "Saved " << nEvents << " events to " << outfile << std::endl;
    return 0;
}