#!/bin/bash

# ENCRYPTCALCURSE.SH

# Written by Oz Nahum <nahumoz__at_you_know_where_no_spam_is_gmail.com>
# This script is distributed under the terms of the GNU Public License 
# Version 3 or later.
# You can obtaion copies of this license at:
# http://www.gnu.org/licenses/gpl.html

# A script to decrypt the calcurse_date dir, open it in 
# /home/<user>/calcurse_data
# then launch calcurse pointing to it, 
# and upon closing calcurse, encrypt the data, move it to usb stick, 
# and delete all data from /home/<user>/calcurse_data

### Begin of Script

INPUT_FILE="calcurse_d.tar.enc"
OUTPUT_FILE="calcurse_d.tar.enc"

#name of directory to encrypt (e.g. ~.calcurse)
CALCURSE_DATA_DIR="~/.calcurse/"

# usage:
# $ bash encryptCalcurse.sh 
# $ bash encryptCalcurse.sh [ecnrypted_data_in.enc] [encrypted_data_out.enc]

#TODO: test that modified script !
### Begin of Script
#make files readable only by owner
umask 077

function Config {
    USB=`pwd`
    tar -cf calcurse_data.tar $CALCURSE_DATA_DIR
    openssl aes-256-cbc -salt -in calcurse_data.tar -out calcurse_d.tar.enc
    clc=`which calcurse`
    cp -v $clc $USB
    
}

function cleanUp {
    find /dev/shm/calcurse_data -type f | xargs shred -fuz;
    if [ -f /dev/shm/cdt.tar ]; then
        shred -fuz /dev/shm/cdt.tar
    fi
    if [ -f /dev/shm/calcurse_data_tmp.tar ]; then
        shred -fuz /dev/shm/calcurse_data_tmp.tar
    fi
    rmdir /dev/shm/calcurse_data/notes
    rmdir /dev/shm/calcurse_data
}

function readData {
#first decrypt the data
openssl enc -d -aes-256-cbc -salt -in $INPUT_FILE -out /dev/shm/calcurse_data_tmp.tar
echo "extracting data"
#silently extract data, no need for verbose output (v flag)
tar -C /dev/shm -xf /dev/shm/calcurse_data_tmp.tar
#note unpacking removes the original tar
}

function encryptData {
openssl aes-256-cbc -salt -in /dev/shm/cdt.tar -out calcurse_d.tar.enc
}


case "$1" in
    "")
    echo "expecting parameter input... see header of script for usage"
    ;;
    "--config")
        CALCURSE_DATA_DIR=$2    
        Config
    ;;

    "--read")
        trap "cleanUp" SIGHUP SIGINT SIGQUIT SIGKILL SIGABRT SIGTERM EXIT
        # when calcurse is done tar the direcotry
        readData
        calcurse -D /dev/shm/calcurse_data
        tar -cf /dev/shm/cdt.tar -C /dev/shm/ calcurse_data/
            
        # then encrypt
        # if encryption failed $? == 1 so repeat it again ...
        encryptData
        es=$?
        while [ "$es" = "1" ]; do 
            echo "encrypting data"
            encryptData
            es=$?    
        done
    ;;
    "--decrypt")
        readData
    ;;
    "--encrypt")
        tar -cvf /dev/shm/cdt.tar -C /dev/shm/ calcurse_data/
        encryptData
    ;;

        #if encryption succeeded clean up by calling the function
        #cleanUp
    
esac
#note about the salt option note found in openssl man page[1],[2]
#note about lack of compresion with ssl [3]

#sources:
#[1]http://ubuntuforums.org/showpost.php?p=8287351&postcount=9
#[2]http://linux.die.net/man/1/enc
#[3]http://serverfault.com/questions/17855/can-i-compr:ess-an-encrypted-file