// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
//
// Generates random paths through an FST.

#include <cstring>

#include <memory>
#include <string>

#include <fst/flags.h>
#include <fst/log.h>
#include <fst/script/getters.h>
#include <fst/script/randgen.h>

DECLARE_int32(max_length);
DECLARE_int32(npath);
DECLARE_int32(seed);
DECLARE_string(select);
DECLARE_bool(weighted);
DECLARE_bool(remove_total_weight);

int fstrandgen_main(int argc, char **argv) {
  namespace s = fst::script;
  using fst::script::FstClass;
  using fst::script::VectorFstClass;

  string usage = "Generates random paths through an FST.\n\n  Usage: ";
  usage += argv[0];
  usage += " [in.fst [out.fst]]\n";

  std::set_new_handler(FailedNewHandler);
  SET_FLAGS(usage.c_str(), &argc, &argv, true);
  if (argc > 3) {
    ShowUsage();
    return 1;
  }

  VLOG(1) << argv[0] << ": Seed = " << FLAGS_seed;

  const string in_name = (argc > 1 && strcmp(argv[1], "-") != 0) ? argv[1] : "";
  const string out_name = argc > 2 ? argv[2] : "";

  std::unique_ptr<FstClass> ifst(FstClass::Read(in_name));
  if (!ifst) return 1;

  VectorFstClass ofst(ifst->ArcType());

  s::RandArcSelection ras;
  if (!s::GetRandArcSelection(FLAGS_select, &ras)) {
    LOG(ERROR) << argv[0] << ": Unknown or unsupported select type "
               << FLAGS_select;
    return 1;
  }

  s::RandGen(*ifst, &ofst, FLAGS_seed,
             fst::RandGenOptions<s::RandArcSelection>(
                 ras, FLAGS_max_length, FLAGS_npath, FLAGS_weighted,
                 FLAGS_remove_total_weight));

  return !ofst.Write(out_name);
}