#!/bin/sh

_printhelp()
{
    cat <<EOF
Usage: ${1##*/} [-m METHOD] [-v] FILES|FOLDERS

Create an archive in current folder from a single or multiples
files/folders. Each input entry will be at archive root (no absolute path is
used). If only one file/folder is given as input, then the archive is named
after this input. Otherwise it is named after current PWD.

  -h:  Display this help.
  -m:  Choose compression method.
         * gz:   gzip (default).
         * none: Simple tar archive.
         * xz:   LZMA.
  -i:  The archive is created without owner/group information. (GNU tar only.)
  -v:  Exclude VCS data. (GNU tar only.)
EOF
}

OUTPATH="$PWD"
ARCEXT=".gz"
ARCOPT="z"
OPTIONS=""
while getopts ":him:v" opt; do
    case $opt in
        h)
            _printhelp "$0"
            exit 1 ;;
        i)
            OPTIONS="$OPTIONS --owner=root --group=root --numeric-owner" ;;
        m)
            [ "$OPTARG" = "gz" ] && ARCEXT=".gz" && ARCOPT="z"
            [ "$OPTARG" = "xz" ] && ARCEXT=".xz" && ARCOPT="J"
            [ "$OPTARG" = "none" ] && ARCEXT="" && ARCOPT=""
            ;;
        v)
            OPTIONS="$OPTIONS --exclude-vcs" ;;
        ?)
            _printhelp "$0"
            exit 1 ;;
        :)
            echo "Missing argument."
            _printhelp "$0"
            exit 1 ;;
    esac
done


shift $(($OPTIND - 1))

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

## Only one input entry: use it as base name for the archive.
if [ $# -eq 1 ]; then
    REALPATH="$(realpath "$1")"
    OUTFILE="${REALPATH##*/}-$(date +%F-%H%M%S).tar${ARCEXT}"
else
    OUTFILE="${PWD##*/}-$(date +%F-%H%M%S).tar${ARCEXT}"
fi

REALPWD="$(realpath "$PWD")"
for i; do
    REALPATH="$(realpath "$i")"

    ## Check if one of the arguments is current folder. We need to make sure the
    ## archive is not created in an input folder, otherwise it will include
    ## itself.
    if [ "$REALPATH" = "$REALPWD" ]; then
        OUTPATH="$(realpath "$REALPWD/..")"
        break
    fi
done


if [ ! -w "$OUTPATH" ]; then
    echo "[$OUTPATH] is not writable. Exiting."
    exit
fi

echo "==> [$OUTPATH/$OUTFILE]"
for i; do
    REALPATH="$(realpath "$i")"
    echo "${REALPATH}" >&2
    echo "-C '${REALPATH%/*}'"
    echo "${REALPATH##*/}"
done | tar $OPTIONS -${ARCOPT}cf "$OUTPATH/$OUTFILE" -T -