#! /bin/bash
usage()
{
cat << EOF
usage $0 options

This script will decrypt any pdf given to it. The correct password has to be passed.

REQUIRES qpdf

OPTIONS:
 -h                 Shows this message
 -p <password>      The password to be used
 -v                 Verbose output
EOF
}

# checks if 'qpdf' is installed
type -P qpdf &>/dev/null || { echo "I require qpdf but it's not installed.  Aborting." >&2; exit 1; }

PWD=

while getopts "hp:v" OPT; do
    case $OPT in
        h)
            usage
            exit EXIT_SUCCESS
            ;;
        p)
            PWD=$OPTARG
            ;;
        v)
            VERBOSE=1
            ;;
        ?)
            usage
            exit 
            ;;
    esac
    shift $((OPTIND-1))
done

ARGS=$@
if [[ -z $ARGS ]] || [[ -z $PWD ]] || ! type -P qpdf &> /dev/null; then
    usage
    exit
fi

shopt -s nullglob       # w/o this '*.pdf' will return the string if no pdfs are in the folder
for DST in $ARGS; do
    if [[ -d $DST ]]; then
        for F in $DST/*.pdf; do
            [[ $VERBOSE ]] && echo $F
            mv $F tmp.pdf
            qpdf --password=$PWD --decrypt $F ${F%.pdf}_.pdf || echo "error"

        done
    elif [[ ${DST##*.} = "pdf" ]] && [[ -f $DST ]]; then
        [[ $VERBOSE ]] && echo $DST
        qpdf --password=$PWD --decrypt $DST ${DST%.pdf}_.pdf
    fi
done