#!/bin/bash
  
  # Copyright 2012  Arnab Ghoshal
  # Copyright 2010-2011  Microsoft Corporation
  
  # 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.
  
  # To be run from ..
  # Triphone model training, using (e.g. MFCC) + delta + acceleration features and
  # cepstral mean normalization.  It starts from an existing directory (e.g.
  # exp/mono), supplied as an argument, which is assumed to be built using the same
  # type of features.
  #
  # This script starts from previously generated state-level alignments
  # (in $alidir), e.g. generated by a previous monophone or triphone
  # system.  To build a context-dependent triphone system, we build 
  # decision trees that map a 3-phone phonetic context window to a
  # pdf index.  It's not really clear which is the right reference, but
  # on is "Tree-based state tying for high accuracy acoustic modelling"
  # by Steve Young et al.  
  # In a typical approach, there are decision trees for
  # each monophone HMM-state (i.e. 3 per phone), and each one gets to
  # ask questions about the left and right phone.  These questions
  # correspond to sets of phones, corresponding to phonetic classes
  # (e.g. vowel, consonant, liquid, solar, ... ).  In Kaldi, we prefer
  # fully automatic algorithms, and anyway we're not sure where to get
  # these types of lists, so we just generate the classes automatically.
  # This is based on a top-down binary tree clustering of the phones
  # (see "cluster-phones"), where we take single-Gaussian statistics for 
  # just the central state of each phone (assuming this to be more 
  # representative of the phones), and we get a tree structure on the
  # phones; each class corresponds to a node of the tree (it contains all 
  # the phones that are children of that node).  Note: you could
  # replace questions.txt with something derived from manually written
  # questions.
  #  Also, the roots of the tree correspond to classes of phones (typically
  # corresponding to "real phones", because the actual phones may contain
  # word-begin/end and stress information), and the tree gets to ask
  # questions also about the central phone, and about the state in the HMM.
  #  After building the tree, we do a number of iterations of Gaussian
  # Mixture Model training; on selected iterations we redo the Viterbi
  # alignments (initially, these are taken from the previous system).
  # The Gaussian mixture splitting, whereby we go from a single Gaussian
  # per state to multiple Gaussians, is done on all iterations (although
  # we stop doing this a few iterations before the end).  We don't have
  # a fixed number of Gaussians per state, but we have an overall target
  # #Gaussians that's specified on each iteration, and we allocate
  # the Gaussians among states according to a power-law where the #Gaussians
  # is proportional to the count to the power 0.2.  The target
  # increases linearly during training [note: logarithmically seems more
  # natural but didn't work as well.]
  
  function error_exit () {
    echo -e "$@" >&2; exit 1;
  }
  
  function readint () {
    local retval=${1/#*=/};  # In case --switch=ARG format was used
    retval=${retval#0*}      # Strip any leading 0's
    [[ "$retval" =~ ^-?[1-9][0-9]*$ ]] \
      || error_exit "Argument \"$retval\" not an integer."
    echo $retval
  }
  
  nj=4       # Default number of jobs
  qcmd=""    # Options for the submit_jobs.sh script
  sjopts=""  # Options for the submit_jobs.sh script
  
  PROG=`basename $0`;
  usage="Usage: $PROG [options] <num-leaves> <data-dir> <lang-dir> <ali-dir> <exp-dir>
  
  e.g.: $PROG 2000 data/train_si84 data/lang exp/mono_ali exp/tri1
  
  
  Options:
  
    --help\t\tPrint this message and exit
  
    --num-jobs INT\tNumber of parallel jobs to run (default=$nj).
  
    --qcmd STRING\tCommand for submitting a job to a grid engine (e.g. qsub) including switches.
  
    --sjopts STRING\tOptions for the 'submit_jobs.sh' script
  
  ";
  
  while [ $# -gt 0 ]; do
    case "${1# *}" in  # ${1# *} strips any leading spaces from the arguments
      --help) echo -e $usage; exit 0 ;;
      --num-jobs) 
        shift; nj=`readint $1`;
        [ $nj -lt 1 ] && error_exit "--num-jobs arg '$nj' not positive.";
        shift ;;
      --qcmd)
        shift; qcmd=" --qcmd=${1}"; shift ;;
      --sjopts)
        shift; sjopts="$1"; shift ;;
      -*)  echo "Unknown argument: $1, exiting"; echo -e $usage; exit 1 ;;
      *)   break ;;   # end of options: interpreted as num-leaves
    esac
  done
  
  if [ $# != 5 ]; then
    error_exit $usage;
  fi
  
  [ -f path.sh ] && . ./path.sh
  
  numleaves=$1
  data=$2
  lang=$3
  alidir=$4
  dir=$5
  
  if [ ! -f $alidir/final.mdl ]; then
    echo "Error: alignment dir $alidir does not contain final.mdl"
    exit 1;
  fi
  
  silphonelist=`cat $lang/silphones.csl`
  
  mkdir -p $dir/log
  if [ ! -d $data/split$nj -o $data/split$nj -ot $data/feats.scp ]; then
    split_data.sh $data $nj
  fi
  
  featspart="ark,s,cs:apply-cmvn --norm-vars=false --utt2spk=ark:$data/split$nj/TASK_ID/utt2spk ark:$alidir/TASK_ID.cmvn scp:$data/split$nj/TASK_ID/feats.scp ark:- | add-deltas ark:- ark:- |"
  
  # The next stage assumes we won't need the context of silence, which
  # assumes something about $lang/roots.txt, but it seems pretty safe.
  echo "Accumulating tree stats"
  submit_jobs.sh "$qcmd" --njobs=$nj --log=$dir/log/acc_tree.TASK_ID.log \
    $sjopts acc-tree-stats --ci-phones=$silphonelist $alidir/final.mdl \
    "$featspart" "ark:gunzip -c $alidir/TASK_ID.ali.gz|" $dir/TASK_ID.treeacc \
    || error_exit "Error accumulating tree stats";
  sum-tree-stats $dir/treeacc $dir/*.treeacc 2>$dir/log/sum_tree_acc.log \
    || error_exit "Error summing tree stats.";
  rm $dir/*.treeacc
  
  # preparing questions, roots file...
  echo "Computing questions for tree clustering"
  ( set -e
    sym2int.pl $lang/phones.txt $lang/phonesets_cluster.txt > $dir/phonesets.txt
    cluster-phones $dir/treeacc $dir/phonesets.txt $dir/questions.txt \
      2> $dir/log/questions.log
    [ -f $lang/extra_questions.txt ] && sym2int.pl $lang/phones.txt \
      $lang/extra_questions.txt >> $dir/questions.txt
    compile-questions $lang/topo $dir/questions.txt $dir/questions.qst \
      2>$dir/log/compile_questions.log
    sym2int.pl --ignore-oov $lang/phones.txt $lang/roots.txt > $dir/roots.txt
  ) || error_exit "Error in generating questions for tree clustering."
  
  echo "Building tree"
  submit_jobs.sh "$qcmd" --log=$dir/log/train_tree.log $sjopts \
    build-tree --verbose=1 --max-leaves=$numleaves $dir/treeacc $dir/roots.txt \
      $dir/questions.qst $lang/topo $dir/tree \
      || error_exit "Error in building tree.";
  echo $numleaves > $dir/numleaves
  
  # Print out summary of the warning messages.
  for x in $dir/log/*.log; do 
    n=`grep WARNING $x | wc -l`; 
    if [ $n -ne 0 ]; then echo $n warnings in $x; fi; 
  done
  
  echo Done