#!/bin/sh
# recompress as .tar.xz
set -e

p_err() {
 printf "ERR: %s\n" "$@" >&2
 exit 1
}
p_dbg() {
 exit $(
  e="$1"
  shift 1 2>/dev/null
  printf "\033[32m [*] %s\033[0m\n" "$@" >&2
  echo "$e"
 )
}
p_msg() {
 printf "\033[1m=>\033[0m %s\n" "$@" >&2
}
p_warn() {
 printf "\033[1mWARN\033[0m %s\n" "$@" >&2
}

p_name="${0##*/}"
usage() {
 printf >&2 "%s\n" 'USAGE'\
 " $p_name dir [opts...]"\
 " $p_name -r DIR"\
 'where'
 ' dir   tar-archive or folder to be repacked'\
 ' opts  options for xz'\
 ' -r    forget xz, (create raw tarfile)'
 exit 1
}

raw=false
while [ $# -gt 0 ]; do
 case "$1" in
 -r) raw=true; shift 1;;
 *) break;;
 esac; done

f=$(basename "$1"); [ -n "${f:+s}" ]||usage
l=$(dirname "$1")
shift 1
p() {( p="$l/$f"; p="${p#./}"; echo "$p" )}
opts="${@:--6}"

trash() {
 if [ -e "$1" ]; then
  p_msg "reusing $1"
  return 1
 else
  p_warn "new trash, $1"
  return 0
 fi
}

t_ex() {
 f=$(
 case "$(p)" in
  *.t*bz2) O="-j" ;;
  *.t*gz) O="-z" ;;
  *.t*xz) O="-J" ;;
  *.tar) : ;;
  *) p_err "$(p) - archive not supported" ;;
 esac
 if [ 1 -lt "$(cd "$l"; tar $O -tf "$f" |grep -o "^[^/]*" |uniq |wc -l)" ]; then
  p="${f%.t*}"
  #p_dbg 2 "[$f : $p]"
  trash "$p" && (cd "$l"; mkdir "$p")
  (cd "$l/$p"; tar $O -xf "../$f")
 else
  p=$(cd "$l"; tar $O -tf "$f" |sed 'q')
  p="${p#./}"
  p="${p%/}"
  #p_dbg 2 "[$f : $p]"
  trash "$p" && (cd "$l"; tar $O -xf "$f")
 fi
 echo "$p"
 )
}
t_pc() {
 #p_dbg 1 "[$l : $f : $(p)] >$(p).tar.xz"
 if ! $raw; then
  p_msg "cd $l; tar >$f.tar.xz"
  (cd "$l"; tar --group 0 --owner 0 -cf - "$f" |xz $opts >"$f.tar.xz")
 else
  p_msg "cd $l; tar >$f.tar"
  (cd "$l"; tar --group 0 --owner 0 -cf - "$f" >"$f.tar")
 fi
}

if [ -d "$(p)" ]; then
 t_pc
elif [ -e "$(p)" ]; then
 t_ex
 t_pc
else
 p_err "$(p) does not exist..."
fi