/*
** Copyright (C) 2018-2021 Alexander Lindemann, Max Luebke (University of
** Potsdam)
**
** Copyright (C) 2018-2022 Marco De Lucia, Max Luebke (GFZ Potsdam)
**
** Copyright (C) 2023-2024 Max Luebke (University of Potsdam)
**
** POET is free software; you can redistribute it and/or modify it under the
** terms of the GNU General Public License as published by the Free Software
** Foundation; either version 2 of the License, or (at your option) any later
** version.
**
** POET is distributed in the hope that it will be useful, but WITHOUT ANY
** WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
** A PARTICULAR PURPOSE. See the GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License along with
** this program; if not, write to the Free Software Foundation, Inc., 51
** Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/

#include "Base/Macros.hpp"
#include "Base/RInsidePOET.hpp"
#include "Chemistry/ChemistryModule.hpp"
#include "DataStructures/Field.hpp"
#include "Init/InitialList.hpp"
#include "Transport/DiffusionModule.hpp"

#include <RInside.h>
#include <Rcpp.h>
#include <cstdlib>
#include <mpi.h>
#include <string>

#include "Base/argh.hpp"

#include <poet.hpp>

using namespace std;
using namespace poet;
using namespace Rcpp;

static int MY_RANK = 0;

// HACK: this is a step back as the order and also the count of fields is
// predefined, but it will change in the future
void writeFieldsToR(RInside &R, const Field &trans, const Field &chem) {

  Rcpp::DataFrame t_field(trans.asSEXP());
  R["TMP"] = t_field;
  R.parseEval("mysetup$state_T <- TMP");

  R["TMP"] = chem.asSEXP();
  R.parseEval("mysetup$state_C <- TMP");
}

enum ParseRet { PARSER_OK, PARSER_ERROR, PARSER_HELP };

ParseRet parseInitValues(char **argv, RInsidePOET &R,
                         RuntimeParameters &params) {
  // initialize argh object
  argh::parser cmdl(argv);

  // if user asked for help
  if (cmdl[{"help", "h"}]) {
    if (MY_RANK == 0) {
      MSG("Todo");
      MSG("See README.md for further information.");
    }

    return ParseRet::PARSER_HELP;
  }
  // if positional arguments are missing
  if (!cmdl(3)) {
    if (MY_RANK == 0) {
      ERRMSG("POET needs 3 positional arguments: ");
      ERRMSG("1) the R script defining your simulation runtime.");
      ERRMSG("2) the initial .rds file generated by poet_init.");
      ERRMSG("3) the directory prefix where to save results and profiling");
    }
    return ParseRet::PARSER_ERROR;
  }

  // parse flags and check for unknown
  for (const auto &option : cmdl.flags()) {
    if (!(flaglist.find(option) != flaglist.end())) {
      if (MY_RANK == 0) {
        ERRMSG("Unrecognized option: " + option);
        ERRMSG("Make sure to use available options. Exiting!");
      }
      return ParseRet::PARSER_ERROR;
    }
  }

  // parse parameters and check for unknown
  for (const auto &option : cmdl.params()) {
    if (!(paramlist.find(option.first) != paramlist.end())) {
      if (MY_RANK == 0) {
        ERRMSG("Unrecognized option: " + option.first);
        ERRMSG("Make sure to use available options. Exiting!");
      }
      return ParseRet::PARSER_ERROR;
    }
  }

  params.print_progressbar = cmdl[{"P", "progress"}];

  /*Parse work package size*/
  cmdl("work-package-size", CHEM_DEFAULT_WORK_PACKAGE_SIZE) >>
      params.work_package_size;

  /* Parse DHT arguments */
  params.use_dht = cmdl["dht"];
  params.use_interp = cmdl["interp"];
  // cout << "CPP: DHT is " << ( dht_enabled ? "ON" : "OFF" ) << '\n';

  cmdl("dht-size", CHEM_DHT_SIZE_PER_PROCESS_MB) >> params.dht_size;
  // cout << "CPP: DHT size per process (Byte) = " << dht_size_per_process <<
  // endl;

  cmdl("dht-snaps", 0) >> params.dht_snaps;

  params.use_interp = cmdl["interp"];
  cmdl("interp-size", 100) >> params.interp_size;
  cmdl("interp-min", 5) >> params.interp_min_entries;
  cmdl("interp-bucket-entries", 20) >> params.interp_bucket_entries;

  /*Parse output options*/
  // simparams.store_result = !cmdl["ignore-result"];

  /*Parse output options*/
  // simparams.store_result = !cmdl["ignore-result"];

  if (MY_RANK == 0) {
    // MSG("Complete results storage is " + BOOL_PRINT(simparams.store_result));
    MSG("Work Package Size: " + std::to_string(params.work_package_size));
    MSG("DHT is " + BOOL_PRINT(params.use_dht));

    if (params.use_dht) {
      // MSG("DHT strategy is " + std::to_string(simparams.dht_strategy));
      // MDL: these should be outdated (?)
      // MSG("DHT key default digits (ignored if 'signif_vector' is "
      // 	"defined) = "
      // 	 << simparams.dht_significant_digits);
      // MSG("DHT logarithm before rounding: "
      // 	 << (simparams.dht_log ? "ON" : "OFF"));
      MSG("DHT size per process (Megabyte) = " +
          std::to_string(params.dht_size));
      MSG("DHT save snapshots is " + BOOL_PRINT(params.dht_snaps));
      // MSG("DHT load file is " + chem_params.dht_file);
    }

    if (params.use_interp) {
      MSG("PHT interpolation enabled: " + BOOL_PRINT(params.use_interp));
      MSG("PHT interp-size = " + std::to_string(params.interp_size));
      MSG("PHT interp-min  = " + std::to_string(params.interp_min_entries));
      MSG("PHT interp-bucket-entries = " +
          std::to_string(params.interp_bucket_entries));
    }
  }

  std::string init_file;
  std::string runtime_file;
  std::string out_dir;

  cmdl(1) >> runtime_file;
  cmdl(2) >> init_file;
  cmdl(3) >> out_dir;

  // chem_params.dht_outdir = out_dir;

  /* distribute information to R runtime */
  // if local_rank == 0 then master else worker
  R["local_rank"] = MY_RANK;
  // assign a char* (string) to 'filesim'
  R["filesim"] = wrap(runtime_file);
  // assign a char* (string) to 'fileout'
  R["fileout"] = wrap(out_dir);
  // pass the boolean "store_result" to the R process
  // R["store_result"] = simparams.store_result;
  // // worker count
  // R["n_procs"] = simparams.world_size - 1;
  // // work package size
  // R["work_package_size"] = simparams.wp_size;
  // // dht enabled?
  // R["dht_enabled"] = chem_params.use_dht;
  // // log before rounding?
  // R["dht_log"] = simparams.dht_log;

  try {
    Rcpp::Function source("source");
    Rcpp::Function readRDS("readRDS");

    Rcpp::List init_params_ = readRDS(init_file);
    params.init_params = init_params_;

    Rcpp::List runtime_params =
        source(runtime_file, Rcpp::Named("local", true));
    runtime_params = runtime_params["value"];
    R[r_runtime_parameters] = runtime_params;

    params.timesteps =
        Rcpp::as<std::vector<double>>(runtime_params["timesteps"]);

  } catch (const std::exception &e) {
    ERRMSG("Error while parsing R scripts: " + std::string(e.what()));
    return ParseRet::PARSER_ERROR;
  }
  // eval the init string, ignoring any returns
  // R.parseEvalQ("source(filesim)");
  // R.parseEvalQ("mysetup <- setup");

  // this->chem_params.initFromR(R);

  return ParseRet::PARSER_OK;
}

static Rcpp::List RunMasterLoop(RInside &R, const RuntimeParameters &params,
                                DiffusionModule &diffusion,
                                ChemistryModule &chem) {

  /* Iteration Count is dynamic, retrieving value from R (is only needed by
   * master for the following loop) */
  uint32_t maxiter = params.timesteps.size();

  double sim_time = .0;

  if (params.print_progressbar) {
    chem.setProgressBarPrintout(true);
  }

  /* SIMULATION LOOP */

  double dSimTime{0};
  for (uint32_t iter = 1; iter < maxiter + 1; iter++) {
    double start_t = MPI_Wtime();
    uint32_t tick = 0;
    // cout << "CPP: Evaluating next time step" << endl;
    // R.parseEvalQ("mysetup <- master_iteration_setup(mysetup)");

    const double &dt = params.timesteps[iter - 1];

    //  cout << "CPP: Next time step is " << dt << "[s]" << endl;
    MSG("Next time step is " + std::to_string(dt) + " [s]");

    /* displaying iteration number, with C++ and R iterator */
    MSG("Going through iteration " + std::to_string(iter));
    // MSG("R's $iter: " +
    //     std::to_string((uint32_t)(R.parseEval("mysetup$iter"))) +
    //     ". Iteration");

    /* run transport */
    // TODO: transport to diffusion
    diffusion.simulate(dt);

    chem.GetField().update(diffusion.getField());

    // chem.getfield().update(diffusion.getfield());

    MSG("Chemistry step");

    chem.simulate(dt);

    writeFieldsToR(R, diffusion.getField(), chem.GetField());
    // R["store_result"] = true;
    // R.parseEval("mysetup$store_result <- TRUE");
    diffusion.getField().update(chem.GetField());

    R["req_dt"] = dt;
    R["simtime"] = (sim_time += dt);

    R.parseEval("mysetup$req_dt <- req_dt");
    R.parseEval("mysetup$simtime <- simtime");

    R["iter"] = iter;

    // MDL master_iteration_end just writes on disk state_T and
    // state_C after every iteration if the cmdline option
    // --ignore-results is not given (and thus the R variable
    // store_result is TRUE)
    R.parseEval("mysetup <- master_iteration_end(setup=mysetup, iter)");

    MSG("End of *coupling* iteration " + std::to_string(iter) + "/" +
        std::to_string(maxiter));
    MSG();

    // MPI_Barrier(MPI_COMM_WORLD);
    double end_t = MPI_Wtime();
    dSimTime += end_t - start_t;
  } // END SIMULATION LOOP

  Rcpp::List chem_profiling;
  chem_profiling["simtime"] = chem.GetChemistryTime();
  chem_profiling["loop"] = chem.GetMasterLoopTime();
  chem_profiling["sequential"] = chem.GetMasterSequentialTime();
  chem_profiling["idle_master"] = chem.GetMasterIdleTime();
  chem_profiling["idle_worker"] = Rcpp::wrap(chem.GetWorkerIdleTimings());
  chem_profiling["phreeqc_time"] = Rcpp::wrap(chem.GetWorkerPhreeqcTimings());

  Rcpp::List diffusion_profiling;
  diffusion_profiling["simtime"] = diffusion.getTransportTime();

  if (params.use_dht) {
    chem_profiling["dht_hits"] = Rcpp::wrap(chem.GetWorkerDHTHits());
    chem_profiling["dht_evictions"] = Rcpp::wrap(chem.GetWorkerDHTEvictions());
    chem_profiling["dht_get_time"] = Rcpp::wrap(chem.GetWorkerDHTGetTimings());
    chem_profiling["dht_fill_time"] =
        Rcpp::wrap(chem.GetWorkerDHTFillTimings());
  }

  if (params.use_interp) {
    chem_profiling["interp_w"] =
        Rcpp::wrap(chem.GetWorkerInterpolationWriteTimings());
    chem_profiling["interp_r"] =
        Rcpp::wrap(chem.GetWorkerInterpolationReadTimings());
    chem_profiling["interp_g"] =
        Rcpp::wrap(chem.GetWorkerInterpolationGatherTimings());
    chem_profiling["interp_fc"] =
        Rcpp::wrap(chem.GetWorkerInterpolationFunctionCallTimings());
    chem_profiling["interp_calls"] =
        Rcpp::wrap(chem.GetWorkerInterpolationCalls());
    chem_profiling["interp_cached"] = Rcpp::wrap(chem.GetWorkerPHTCacheHits());
  }

  Rcpp::List profiling;
  profiling["simtime"] = dSimTime;
  profiling["chemistry"] = chem_profiling;
  profiling["diffusion"] = diffusion_profiling;

  chem.MasterLoopBreak();

  return profiling;
}

int main(int argc, char *argv[]) {
  double dSimTime, sim_end;

  int world_size;

  MPI_Init(&argc, &argv);

  MPI_Comm_size(MPI_COMM_WORLD, &world_size);
  MPI_Comm_rank(MPI_COMM_WORLD, &MY_RANK);

  RInsidePOET &R = RInsidePOET::getInstance();

  if (MY_RANK == 0) {
    MSG("Running POET version " + std::string(poet_version));
  }

  /*Loading Dependencies*/
  // TODO: kann raus
  R.parseEvalQ(kin_r_library);

  RuntimeParameters run_params;

  switch (parseInitValues(argv, R, run_params)) {
  case ParseRet::PARSER_ERROR:
  case ParseRet::PARSER_HELP:
    MPI_Finalize();
    return 0;
  case ParseRet::PARSER_OK:
    break;
  }

  InitialList init_list(R);
  init_list.importList(run_params.init_params);

  MSG("RInside initialized on process " + std::to_string(MY_RANK));

  ChemistryModule chemistry(run_params.work_package_size,
                            init_list.getChemistryInit(), MPI_COMM_WORLD);

  const ChemistryModule::SurrogateSetup surr_setup = {
      init_list.getInitialGrid().GetProps(),
      run_params.use_dht,
      run_params.dht_size,
      run_params.use_interp,
      run_params.interp_bucket_entries,
      run_params.interp_size,
      run_params.interp_min_entries};

  chemistry.masterEnableSurrogates(surr_setup);

  if (MY_RANK > 0) {

    chemistry.WorkerLoop();

    MPI_Barrier(MPI_COMM_WORLD);

    MSG("finished, cleanup of process " + std::to_string(MY_RANK));

    MPI_Finalize();

    return EXIT_SUCCESS;
  }

  // R.parseEvalQ("mysetup <- setup");
  // // if (MY_RANK == 0) { // get timestep vector from
  // // grid_init function ... //
  std::string master_init_code = "mysetup <- master_init(setup=mysetup)";
  R.parseEval(master_init_code);

  // run_params.initVectorParams(R);

  // MDL: store all parameters
  if (MY_RANK == 0) {
    MSG("Calling R Function to store calling parameters");
    // R.parseEvalQ("StoreSetup(setup=mysetup)");
  }

  if (MY_RANK == 0) {
    MSG("Init done on process with rank " + std::to_string(MY_RANK));
  }

  // MPI_Barrier(MPI_COMM_WORLD);

  DiffusionModule diffusion(init_list.getDiffusionInit(),
                            init_list.getInitialGrid());

  chemistry.masterSetField(init_list.getInitialGrid());

  Rcpp::List profiling = RunMasterLoop(R, run_params, diffusion, chemistry);

  MSG("finished simulation loop");

  MSG("start timing profiling");

  // R["simtime"] = dSimTime;
  // R.parseEvalQ("profiling$simtime <- simtime");

  R["profiling"] = profiling;

  string r_vis_code;
  r_vis_code = "saveRDS(profiling, file=paste0(fileout,'/timings.rds'));";
  R.parseEval(r_vis_code);

  // MSG("Done! Results are stored as R objects into <" + run_params.getOutDir()
  // +
  //     "/timings.rds>");

  MPI_Barrier(MPI_COMM_WORLD);

  MSG("finished, cleanup of process " + std::to_string(MY_RANK));
  MPI_Finalize();

  if (MY_RANK == 0) {
    MSG("done, bye!");
  }

  exit(0);
}