#!/bin/sh
# Copyright (c) 2013 Stefan Huber
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.

# Author: Stefan Huber <shuber@sthu.org>

#
# This script does a decrypt-edit-encrypt cycle with gpg and OpenOffice resp.
# LibreOffice files.


SUMCMD="sha1sum"
CRYPTID=""

CMD="/usr/bin/libreoffice"
[ -x ${CMD} ] || CMD="/usr/bin/ooffice"

[ -f "$HOME/.office-gpg.cfg" ] && source "$HOME/.office-gpg.cfg"

if [ -z "$CRYPTID" ]; then
	echo "No CRYPTID set in $HOME/.office-gpg.cfg"
	exit 1
fi

#No valid invocation
if [ $# -ne 1 ]
then
	echo "Usage: $CMD-gpg <gpg-file>"
	exit -1
fi


#The corresponding gpg-file
gpgfile=$1

if [ ! -f "$gpgfile" ]
then
	echo "\`$gpgfile\` does not exist..."
else
	echo "Opening \`$gpgfile\`..."
fi



#Search for filename to to encrypt file to...
uncryptfilePost=${gpgfile%%.gpg}
i=1
uncryptfile="$i.$uncryptfilePost"

while [ -f "$uncryptfile" ]
do
	let "i = $i + 1"
	uncryptfile="$i.$uncryptfilePost"
done


echo "Uncrypt \`$gpgfile\` to  \`$uncryptfile\`..."



#Decrypt file and get checksum...
gpg  --output "$uncryptfile" --decrypt "$gpgfile"
hsumpre=`$SUMCMD "$uncryptfile" | awk '{ print $1 }'`
echo "Checksum is '$hsumpre'."


#Edit file and get checksum of altered file
$CMD "$uncryptfile"
#pid=`lsof | grep "$uncryptfile" | cut -d ' ' -f 2`
#echo "wait for pid: $pid"
#while [ -n "`ps | grep "$pid"`" ] ; do
#        sleep 1
#done


hsumpost=`$SUMCMD "$uncryptfile" | awk '{ print $1 }'`
echo "Checksum is '$hsumpost'."


#Check if file has been altered
if [ "$hsumpost" != "$hsumpre" ]
then
	gpg --output "$gpgfile" -r "$CRYPTID" --encrypt "$uncryptfile" 

	#Get checksum of crypted version
	hsumcrypt=`gpg --decrypt $gpgfile | $SUMCMD | awk '{ print $1 }'`
	echo "Checksum of crypted file is '$hsumcrypt'"

	if [ "$hsumpost" != "$hsumcrypt" ]
	then
		echo ""
		echo "*** WARNING ***"
		echo "*** WARNING ***   Encrypted file \`$gpgfile\` leads to different checksum."
		echo "*** WARNING ***   Not removing unencrypted file \`$uncryptfile\`."
		echo "*** WARNING ***"
		echo ""

		exit -1
	fi

else
	echo "No changes. Skip re-encrypting"
fi




#Remove old file...
rm -i "$uncryptfile"


#File not removed!?
if [ -f "$uncryptfile" ]
then
	echo ""
	echo "*** WARNING ***"
	echo "*** WARNING ***   Unencrypted file \`$uncryptfile\` not removed!"
	echo "*** WARNING ***"
	echo ""
fi