// latbin/lattice-determinize-pruned.cc

// Copyright 2013  Daniel Povey (Johns Hopkins University)

// See ../../COPYING for clarification regarding multiple authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.
#include "base/kaldi-common.h"
#include "util/common-utils.h"
#include "lat/kaldi-lattice.h"
#include "lat/determinize-lattice-pruned.h"
#include "lat/lattice-functions.h"
#include "lat/push-lattice.h"
#include "lat/minimize-lattice.h"

int main(int argc, char *argv[]) {
  try {
    using namespace kaldi;
    typedef kaldi::int32 int32;

    const char *usage =
        "Determinize lattices, keeping only the best path (sequence of acoustic states)\n"
        "for each input-symbol sequence.  This version does pruning as part of the\n"
        "determinization algorithm, which is more efficient and prevents blowup.\n"
        "See http://kaldi-asr.org/doc/lattices.html for more information on lattices.\n"
        "\n"
        "Usage: lattice-determinize-pruned [options] lattice-rspecifier lattice-wspecifier\n"
        " e.g.: lattice-determinize-pruned --acoustic-scale=0.1 --beam=6.0 ark:in.lats ark:det.lats\n";

    ParseOptions po(usage);
    bool write_compact = true;
    BaseFloat acoustic_scale = 1.0;
    BaseFloat beam = 10.0;
    bool minimize = false;
    fst::DeterminizeLatticePrunedOptions opts; // Options used in DeterminizeLatticePruned--
    // this options class does not have its own Register function as it's viewed as
    // being more part of "fst world", so we register its elements independently.
    opts.max_mem = 50000000;
    opts.max_loop = 0; // was 500000;

    po.Register("write-compact", &write_compact, 
                "If true, write in normal (compact) form. "
                "--write-compact=false allows you to retain frame-level "
                "acoustic score information, but this requires the input "
                "to be in non-compact form e.g. undeterminized lattice "
                "straight from decoding.");
    po.Register("acoustic-scale", &acoustic_scale,
                "Scaling factor for acoustic likelihoods");
    po.Register("beam", &beam, "Pruning beam [applied after acoustic scaling].");
    po.Register("minimize", &minimize,
                "If true, push and minimize after determinization");
    opts.Register(&po);
    po.Read(argc, argv);

    if (po.NumArgs() != 2) {
      po.PrintUsage();
      exit(1);
    }

    std::string lats_rspecifier = po.GetArg(1),
        lats_wspecifier = po.GetArg(2);


    // Read as regular lattice-- this is the form the determinization code
    // accepts.
    SequentialLatticeReader lat_reader(lats_rspecifier);

    CompactLatticeWriter compact_lat_writer;
    LatticeWriter lat_writer;

    if (write_compact)
      compact_lat_writer.Open(lats_wspecifier);
    else
      lat_writer.Open(lats_wspecifier);

    int32 n_done = 0, n_warn = 0;

    // depth stats (for diagnostics).
    double sum_depth_in = 0.0,
          sum_depth_out = 0.0, sum_t = 0.0;

    if (acoustic_scale == 0.0)
      KALDI_ERR << "Do not use a zero acoustic scale (cannot be inverted)";

    for (; !lat_reader.Done(); lat_reader.Next()) {
      std::string key = lat_reader.Key();
      Lattice lat = lat_reader.Value();

      KALDI_VLOG(2) << "Processing lattice " << key;

      // Compute a map from each (t, tid) to (sum_of_acoustic_scores, count)
      unordered_map<std::pair<int32,int32>, std::pair<BaseFloat, int32>,
                                          PairHasher<int32> > acoustic_scores;
      if (!write_compact)
        ComputeAcousticScoresMap(lat, &acoustic_scores);

      Invert(&lat); // so word labels are on the input side.
      lat_reader.FreeCurrent();
      fst::ScaleLattice(fst::AcousticLatticeScale(acoustic_scale), &lat);
      if (!TopSort(&lat)) {
        KALDI_WARN << "Could not topologically sort lattice: this probably means it"
            " has bad properties e.g. epsilon cycles.  Your LM or lexicon might "
            "be broken, e.g. LM with epsilon cycles or lexicon with empty words.";
      }
      fst::ArcSort(&lat, fst::ILabelCompare<LatticeArc>());
      CompactLattice det_clat;
      if (!DeterminizeLatticePruned(lat, beam, &det_clat, opts)) {
        KALDI_WARN << "For key " << key << ", determinization did not succeed"
            "(partial output will be pruned tighter than the specified beam.)";
        n_warn++;
      }
      fst::Connect(&det_clat);
      if (det_clat.NumStates() == 0) {
        KALDI_WARN << "For key " << key << ", determinized and trimmed lattice "
            "was empty.";
        n_warn++;
      }
      if (minimize) {
        PushCompactLatticeStrings(&det_clat);
        PushCompactLatticeWeights(&det_clat);
        MinimizeCompactLattice(&det_clat);
      }

      int32 t;
      TopSortCompactLatticeIfNeeded(&det_clat);
      double depth = CompactLatticeDepth(det_clat, &t);
      sum_depth_in += lat.NumStates();
      sum_depth_out += depth * t;
      sum_t += t;

      if (write_compact) {
        fst::ScaleLattice(fst::AcousticLatticeScale(1.0/acoustic_scale), &det_clat);
        compact_lat_writer.Write(key, det_clat);
      } else {
        Lattice out_lat;
        fst::ConvertLattice(det_clat, &out_lat);

        // Replace each arc (t, tid) with the averaged acoustic score from
        // the computed map
        ReplaceAcousticScoresFromMap(acoustic_scores, &out_lat);
        lat_writer.Write(key, out_lat);
      }

      n_done++;
    }

    if (sum_t != 0.0) {
      KALDI_LOG << "Average input-lattice depth (measured at at state level) is "
                << (sum_depth_in / sum_t) << ", output depth is "
                << (sum_depth_out / sum_t) << ", over " << sum_t << " frames "
                << " (average num-frames = " << (sum_t / n_done) << ").";
    }
    KALDI_LOG << "Done " << n_done << " lattices, determinization finished "
              << "earlier than specified by the beam (or output was empty) on "
              << n_warn << " of these.";
    return (n_done != 0 ? 0 : 1);
  } catch(const std::exception &e) {
    std::cerr << e.what();
    return -1;
  }
}