#!/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.
  -i:  The archive is created without owner/group information. (GNU tar only.)
  -m:  Choose compression method.
         * gz:   gzip (default).
         * none: Simple tar archive.
         * xz:   LZMA.
  -s:  Archive each input entry an individual file.
  -v:  Exclude VCS data. (GNU tar only.)
EOF
}

OUTPATH="$PWD"
ARCEXT=".gz"
ARCOPT="z"
OPTIONS=""
OPT_SPLIT=false
while getopts ":him:sv" 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"
            [ "$OPTARG" = "none" ] && ARCEXT="" && ARCOPT=""
            ;;
        s)
            OPT_SPLIT=true ;;
        v)
            OPTIONS="$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


_archive()
{
    ## 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."
        return
    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 -
}

if $OPT_SPLIT; then
    for j ; do
        _archive "$j"
    done
else
    _archive "$@"
fi