#!/bin/bash
# Extract subtitles from each MKV file in the given directory

# If no directory is given, work in local dir
if [ "$1" = "" ]; then
  DIR="./"
else
  DIR="$1"
fi

SUBDIR="$DIR/subs"

# Get all the MKV files in this dir and its subdirs
find "$DIR" -maxdepth 1 -type f -name '*.mkv' | while read filename
do
subtitlename=${filename%.*}
plainsubname=${subtitlename/$DIR/}
tmpsubtitle="/tmp/$plainsubname.srt.tmp"
`find ./subs -maxdepth 1 -type f -name "$plainsubname-*.srt" 2>/dev/null | grep -q .srt`
RETVAL=$?

if [ $RETVAL -ne 0 ];
then
echo "no subtitle yet for $filename, scanning"
# Find out which tracks contain the subtitles
  mkvmerge -i "$filename" | grep 'subtitles' | while read subline
  do
    # Grep the number of the subtitle track
    tracknumber=`echo $subline | egrep -o "[0-9]{1,2}" | head -1`

    # Get base name for subtitle
    subtitlename=${filename%.*}

    # Extract the track to a .tmp file
    `mkvextract tracks "$filename" $tracknumber:"$tmpsubtitle" > /dev/null 2>&1`
    `chmod g+rw "$tmpsubtitle"`

    # Do a super-primitive language guess: ENGLISH
    langtest=`egrep -ic ' you | the | just | what ' "$tmpsubtitle"`
    trimregex=""

    # Check if subtitle passes our language filter (10 or more matches)
    if [ $langtest -ge 10 ]; then
      if [ -f  "$tmpsubtitle" ]; then
        # Check the file size for know if it s a forced or a real subtitle
            size_log=$(du "$tmpsubtitle" | cut -f1)
            #echo $size_log
            if [ $size_log -lt 10 ]; then
              # rename forced subtitle for plex
              echo "subtitle forced, $subtitlename"
              `mv "$tmpsubtitle "$SUBDIR/$subtitlename.forced-$tracknumber.srt" > /dev/null 2>&1`
            else
              # Rename for plex
              echo "found sub #track $tracknumber in $subtitlename"
              `mv "$tmpsubtitle" "$SUBDIR/$subtitlename.internal-$tracknumber-en.srt" > /dev/null 2>&1`
            fi
      fi
    else
      if [ -f  "$tmpsubtitle" ]; then
            size_log=$(du "$tmpsubtitle" | cut -f1)
            #echo $size_log
            if [ $size_log -lt 10 ]; then
              echo "subtitle forced, $subtitlename"
              `mv "$tmpsubtitle" "$SUBDIR/$subtitlename.forced-$tracknumber.srt" > /dev/null 2>&1`
            else
              # Subtitle in another language --> delete
              `rm "$tmpsubtitle"  > /dev/null 2>&1`
            fi
          fi
        fi
  done
fi
done