#!/bin/sh

unset DATE

_printhelp ()
{
    cat<<EOF
Usage: ${1##*/} [-f] FOLDERS

Create index of folder hierarchies. This is used as a small "backup" purpose. In
case of data loss, it is still possible to get the full file list thanks to the
indexes.

 -f: Overwrite if output exists.
EOF
}

OPT_NOCLOBBER=true
while getopts ":dfh" opt; do
    case $opt in
        h)
            _printhelp "$0"
            exit 0
            ;;
        f)
            OPT_NOCLOBBER=false
            ;;
        ?)
            _printhelp "$0"
            exit 1
            ;;
        :)
            _printhelp "$0"
            exit 1
            ;;
    esac
done

shift $(($OPTIND - 1))

if [ $# -eq 0 ]; then
    _printhelp "$0"
    exit 1
fi

for i ; do
    base="$(basename "$i")"
    [ ! -d "$i" ] && continue
    OUTPUT="$base.index"
    [ -e "$OUTPUT" ] && $OPT_NOCLOBBER && OUTPUT="$base-$(date +%F-%T).index"
    echo "$OUTPUT"

    ## Find over '.*' and '*', is bad practice since if will fail if no existing
    ## files or for files beginning with a dash. The 'printf' command in find is
    ## for GNU find only.

    ## The two following lines do the same for the same time cost. The former is shorter.
    (cd "$i" && find . -type f) | sed 's/^.\///' | sort > "$OUTPUT"
    # find "$i" -type f | awk -v str="$i" '{l=length(str)+2; print substr($0, l)}' | sort > "$OUTPUT"
done