#!/bin/bash
  
  set -euo pipefail
  
  # This script is modified based on mini_librispeech/s5/local/nnet3/run_ivector_common.sh
  
  # This script is called from local/nnet3/run_tdnn.sh and
  # local/chain/run_tdnn.sh (and may eventually be called by more
  # scripts).  It contains the common feature preparation and
  # iVector-related parts of the script.  See those scripts for examples
  # of usage.
  
  stage=0
  train_set=train
  test_sets="test eval"
  gmm=tri5a
  
  nnet3_affix=
  
  . ./cmd.sh
  . ./path.sh
  . utils/parse_options.sh
  
  gmm_dir=exp/${gmm}
  ali_dir=exp/${gmm}_sp_ali
  
  for f in data/${train_set}/feats.scp ${gmm_dir}/final.mdl; do
    if [ ! -f $f ]; then
      echo "$0: expected file $f to exist"
      exit 1
    fi
  done
  
  if [ $stage -le 1 ]; then
    # Although the nnet will be trained by high resolution data, we still have to
    # perturb the normal data to get the alignment _sp stands for speed-perturbed
    echo "$0: preparing directory for low-resolution speed-perturbed data (for alignment)"
    utils/data/perturb_data_dir_speed_3way.sh data/${train_set} data/${train_set}_sp
    echo "$0: making MFCC features for low-resolution speed-perturbed data"
    steps/make_mfcc_pitch.sh --cmd "$train_cmd" --nj 70 data/${train_set}_sp \
      exp/make_mfcc/${train_set}_sp mfcc_perturbed || exit 1;
    steps/compute_cmvn_stats.sh data/${train_set}_sp \
      exp/make_mfcc/${train_set}_sp mfcc_perturbed || exit 1;
    utils/fix_data_dir.sh data/${train_set}_sp
  fi
  
  if [ $stage -le 2 ]; then
    echo "$0: aligning with the perturbed low-resolution data"
    steps/align_fmllr.sh --nj 30 --cmd "$train_cmd" \
      data/${train_set}_sp data/lang $gmm_dir $ali_dir || exit 1
  fi
  
  if [ $stage -le 3 ]; then
    # Create high-resolution MFCC features (with 40 cepstra instead of 13).
    # this shows how you can split across multiple file-systems.
    echo "$0: creating high-resolution MFCC features"
    mfccdir=mfcc_perturbed_hires
  
    for datadir in ${train_set}_sp ${test_sets}; do
      utils/copy_data_dir.sh data/$datadir data/${datadir}_hires
    done
  
    # do volume-perturbation on the training data prior to extracting hires
    # features; this helps make trained nnets more invariant to test data volume.
    utils/data/perturb_data_dir_volume.sh data/${train_set}_sp_hires || exit 1;
  
    for datadir in ${train_set}_sp ${test_sets}; do
      steps/make_mfcc_pitch.sh --nj 10 --mfcc-config conf/mfcc_hires.conf \
        --cmd "$train_cmd" data/${datadir}_hires exp/make_hires/$datadir $mfccdir || exit 1;
      steps/compute_cmvn_stats.sh data/${datadir}_hires exp/make_hires/$datadir $mfccdir || exit 1;
      utils/fix_data_dir.sh data/${datadir}_hires || exit 1;
      # create MFCC data dir without pitch to extract iVector
      utils/data/limit_feature_dim.sh 0:39 data/${datadir}_hires data/${datadir}_hires_nopitch || exit 1;
      steps/compute_cmvn_stats.sh data/${datadir}_hires_nopitch exp/make_hires/$datadir $mfccdir || exit 1;
    done
  fi
  
  if [ $stage -le 4 ]; then
    echo "$0: computing a subset of data to train the diagonal UBM."
    # We'll use about a quarter of the data.
    mkdir -p exp/nnet3${nnet3_affix}/diag_ubm
    temp_data_root=exp/nnet3${nnet3_affix}/diag_ubm
  
    num_utts_total=$(wc -l <data/${train_set}_sp_hires_nopitch/utt2spk)
    num_utts=$[$num_utts_total/4]
    utils/data/subset_data_dir.sh data/${train_set}_sp_hires_nopitch \
       $num_utts ${temp_data_root}/${train_set}_sp_hires_nopitch_subset
  
    echo "$0: computing a PCA transform from the hires data."
    steps/online/nnet2/get_pca_transform.sh --cmd "$train_cmd" \
        --splice-opts "--left-context=3 --right-context=3" \
        --max-utts 10000 --subsample 2 \
         ${temp_data_root}/${train_set}_sp_hires_nopitch_subset \
         exp/nnet3${nnet3_affix}/pca_transform
  
    echo "$0: training the diagonal UBM."
    # Use 512 Gaussians in the UBM.
    steps/online/nnet2/train_diag_ubm.sh --cmd "$train_cmd" --nj 30 \
      --num-frames 700000 \
      ${temp_data_root}/${train_set}_sp_hires_nopitch_subset 512 \
      exp/nnet3${nnet3_affix}/pca_transform exp/nnet3${nnet3_affix}/diag_ubm
  fi
  
  if [ $stage -le 5 ]; then
    # Train the iVector extractor.  Use all of the speed-perturbed data since iVector extractors
    # can be sensitive to the amount of data.  The script defaults to an iVector dimension of
    # 100.
    echo "$0: training the iVector extractor"
    steps/online/nnet2/train_ivector_extractor.sh --cmd "$train_cmd" --nj 10 \
       data/${train_set}_sp_hires_nopitch exp/nnet3${nnet3_affix}/diag_ubm \
       exp/nnet3${nnet3_affix}/extractor || exit 1;
  fi
  
  if [ $stage -le 6 ]; then
    # We extract iVectors on the speed-perturbed training data after combining
    # short segments, which will be what we train the system on.  With
    # --utts-per-spk-max 2, the script pairs the utterances into twos, and treats
    # each of these pairs as one speaker; this gives more diversity in iVectors..
    # Note that these are extracted 'online'.
  
    # note, we don't encode the 'max2' in the name of the ivectordir even though
    # that's the data we extract the ivectors from, as it's still going to be
    # valid for the non-'max2' data, the utterance list is the same.
  
    ivectordir=exp/nnet3${nnet3_affix}/ivectors_${train_set}_sp
  
    # having a larger number of speakers is helpful for generalization, and to
    # handle per-utterance decoding well (iVector starts at zero).
    temp_data_root=${ivectordir}
    utils/data/modify_speaker_info.sh --utts-per-spk-max 2 \
      data/${train_set}_sp_hires_nopitch ${temp_data_root}/${train_set}_sp_hires_nopitch_max2
    steps/online/nnet2/extract_ivectors_online.sh --cmd "$train_cmd" --nj 30 \
      ${temp_data_root}/${train_set}_sp_hires_nopitch_max2 \
      exp/nnet3${nnet3_affix}/extractor $ivectordir
  
    # Also extract iVectors for the test data, but in this case we don't need the speed
    # perturbation (sp).
    for data in $test_sets; do
      steps/online/nnet2/extract_ivectors_online.sh --cmd "$train_cmd" --nj 8 \
        data/${data}_hires_nopitch exp/nnet3${nnet3_affix}/extractor \
        exp/nnet3${nnet3_affix}/ivectors_${data}
    done
  fi
  
  exit 0