#!/bin/bash

# Template CHanger alternative
# This script uses xmlstarlet, zip and unzip.
echo
echo ./cht.sh, CHange Template...
echo This script inserts or replaces, a template XML node in a 
echo LibreOffice Writer file, by modifying meta.xml. It accepts both
echo document and master document files and template files.
echo xmlstarlet is expected to be installed.
echo This is for documentation projects where Writer files and Templates
echo reside in the same directory!
echo USE AT YOUR OWN RISK, HAVE A BACK-UP READY, wiebe-nedcad-nl
echo Run script always in directory with documents, cd your_project
echo "Usage: cht <OTT-file> <ODT-or-ODM-file>"
echo Example: ./cht.sh template.ott writer.odt
echo

## Variables

# General
TEMPL=$1
DOC=$2
WORKDIR="temp_extracted"

# XML node "meta:template" values
echo Node meta:template will contain the following bare attributes:
# xlink:type xlink:actuate xlink:title xlink:href meta:date

# Static
N_XLINK_TYPE="xlink:type" && V_XLINK_TYPE="simple"
echo $N_XLINK_TYPE -- $V_XLINK_TYPE

# Static
N_XLINK_ACTUATE="xlink:actuate" && V_XLINK_ACTUATE="onRequest"
echo $N_XLINK_ACTUATE -- $V_XLINK_ACTUATE

# Template name
N_XLINK_TITLE="xlink:title"
NO_EXT="${TEMPL%.*}"
V_XLINK_TITLE=${NO_EXT##*/}
echo $N_XLINK_TITLE -- $V_XLINK_TITLE

# Absolute template location
N_XLINK_HREF="xlink:href"
V_XLINK_HREF="$PWD/$TEMPL"
echo $N_XLINK_HREF -- $V_XLINK_HREF

# Template time, Epoch time is lowered a bit to force updating document styles
N_META_DATE="meta:date"
BELLE_EPOCH_COR=-1
BELLE_EPOCH_X=$(stat -c %Y $TEMPL)
BELLE_EPOCH=$((BELLE_EPOCH_X+BELLE_EPOCH_COR))
V_META_DATE=$(date -d @$BELLE_EPOCH +%Y-%m-%dT%T.%9N)
echo $N_META_DATE -- $V_META_DATE
echo

## Checks

# Do files exist with right extension?

if [ -f $TEMPL ] && [ "${TEMPL: -4}" == ".ott" ]; then
   echo "File $TEMPL found."
else
   echo "ERROR: Writer template $TEMPL does not exist or is not valid. Aborting."
   exit 1
fi

if [ -f $DOC ] && ([ "${DOC: -4}" == ".odt" ] || [ "${DOC: -4}" == ".odm" ]); then
   echo "File $DOC found."
else
   echo "ERROR: Writer document $DOC does not exist or is not valid. Aborting."
   exit 1
fi

# Do we have xmlstarlet?

hash xmlstarlet 2>/dev/null || { echo >&2 "ERROR: xmlstarlet is required. Please install this first. Aborting."; exit 1; }

## The proces

# Unzip the document file

mkdir -p $WORKDIR
if [ -z "$(ls -A ./$WORKDIR)" ]; then
   echo "Ready for processing meta.xml"
else
   echo "ERROR: ./$WORKDIR is not empty and may contain an unzipped document file. Aborting."
   exit 1
fi
unzip -q $DOC -d $WORKDIR
cd $WORKDIR

# If exists, delete node meta:template, add node and subnodes via pipes
xmlstarlet ed -d "/office:document-meta/office:meta/meta:template" meta.xml | \
xmlstarlet ed -s  "/office:document-meta/office:meta" -t elem -n meta:template | \
xmlstarlet ed -i  "/office:document-meta/office:meta/meta:template" -t attr -n $N_XLINK_TYPE -v $V_XLINK_TYPE | \
xmlstarlet ed -i  "/office:document-meta/office:meta/meta:template" -t attr -n $N_XLINK_ACTUATE -v $V_XLINK_ACTUATE | \
xmlstarlet ed -i  "/office:document-meta/office:meta/meta:template" -t attr -n $N_XLINK_TITLE -v $V_XLINK_TITLE | \
xmlstarlet ed -i  "/office:document-meta/office:meta/meta:template" -t attr -n $N_XLINK_HREF -v $V_XLINK_HREF | \
xmlstarlet ed -i  "/office:document-meta/office:meta/meta:template" -t attr -n $N_META_DATE -v $V_META_DATE \
> temp.xml && mv temp.xml meta.xml

# What is the result?
echo meta.xml is now: && echo
cat meta.xml && echo

# Back-up original file
mv ../$DOC "../${DOC%.*}.bak"
echo A .bak file is created && echo

# Create modified Writer file, mimetype first
zip -rq ../$DOC mimetype .

# Cleaning up
cd ..
rm -rf $WORKDIR
echo Finished && echo