#!/bin/bash

###############################################
# redfist.sh 0.1                              
# This little script extracts chapter times   
# from HandBrake-encoded movies and translates    
# them into a format readable by mkvmerge. 
###############################################
# It accepts two command-line arguments, the   
# path to the HandBrake-encoded .mp4 to read,
# and the path to a copy of MP4Box.  
###############################################
# For this to work, you obviously have to use
# chapter markers in HandBrake, and for this
# process to be useful, it should be done with
# HandBrake 0.8.5b2 or later, which has precise
# chapter times, instead of following what the
# DVD says.

INPUTFILE="$1"
MP4BOX_PATH="$2"

#############
# SED STUFF 
#############

# First, extract the chapter index to stdout with mp4box. Then, display only
# the lines with the timecodes and chapters on them (starts with "<TextSample").
# Cut away everything before the time, the double quotes that confuse sed, and
# then the rest of the line until the end bracket (">") of the line. Strip
# control characters like ^M, too.

# Store what's left in the TIMECODE array for later use.

TIMECODE=($($MP4BOX_PATH -ttxt 3 $INPUTFILE -std | grep '<TextSample ' | sed -e 's/TTXT.*)//g' -e 's/<TextSample sampleTime="//g' -e 's/"//g' -e 's/text=.*>//g' -e 's/[[:cntrl:]]//g'))

# First, extract the chapter index to stdout with mp4box. Then, display only
# the lines with the timecodes and chapters on them (starts with "<TextSample").
# Cut away everything before the time, the double quotes that confuse sed, 
# everything before the chapter name (through "text="), the single quotes
# which confuse sed, and the bracket (">") at the end of the line.
# Store what's left in the TITLE array for later use. For now, this only works
# when you use the default names ("Chapter XX") because of limitations in how
# bash handles strings in arrays (it delimits on spaces and so I'm assuming
# there will be two spots used in the array per title before the next Chapter).
# Oh yeah, it'd also help if bash arrays were multidimensional.

TITLE=($($MP4BOX_PATH -ttxt 3 $INPUTFILE -std |  grep '<TextSample ' | sed -e 's/TTXT.*)//g' -e 's/<TextSample sampleTime="//g' -e 's/"//g' -e 's/.*text=//g' -e "s/'//g" -e 's/>//g'))

#############
# LOOP PREP 
#############

# For the timecode index and the loop.
ITERATOR1=0
# For the chapter title index.
ITERATOR2=0

# We want to iterate through based on the number of timecodes stored
# in the TIMECODE array.
CHAPTERNUM=$(echo ${#TIMECODE[*]})

# And yet, we don't want the last chapter marker from HandBrake,
# because it's just the last frame of the video. So decrement.
CHAPTERNUM=$((CHAPTERNUM-1))

# This xml header text only needs to be at the top, so
# throw it in before the loop starts.
echo -e "<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>"
echo -e "<!DOCTYPE Chapters SYSTEM \"matroskachapters.dtd\">"
echo -e "<Chapters>"
echo -e "<EditionEntry>"

#######################################
# LOOPING, WHERE THE REAL WORK'S DONE 
#######################################

# Loop through all the chapters.
while [ $ITERATOR1 -lt $CHAPTERNUM ]
do
    echo -e "<ChapterAtom>"
    echo -e "<ChapterTimeStart> \c"

    echo -e ${TIMECODE[$ITERATOR1]} "\c"

    echo -e "</ChapterTimeStart>"
    echo -e "<ChapterDisplay>"

    # Timecode written, it's on to the title.
    
    echo -e "<ChapterString> \c"
    
    # Then, two words from the title array.
    echo -e ${TITLE[$ITERATOR2]} ${TITLE[$ITERATOR2+1]} "\c"

    echo -e "</ChapterString>"
    echo -e "<ChapterLanguage>eng</ChapterLanguage>"
    echo -e "</ChapterDisplay>"
    echo -e "</ChapterAtom>"

    # Iterate the timecodes and the loop by one.
    ITERATOR1=$((ITERATOR1+1))
    
    # Because HandBrake uses two-word title names,
    # and each word is stored separately in the array,
    # iterate it by two to jump past both words used
    # this time through the loop.
    ITERATOR2=$((ITERATOR2+2))
done

#############
# POST LOOP 
#############

# This is just to close out the xml divs.
echo -e "</EditionEntry>"
echo -e "</Chapters>"