#!/bin/sh

# untar
# =====
# Usage: untar FILE [OPTIONS]
#
# Uncompress a tarball. Expects standardized file names (i.e., '.tar.gz.gpg')

help_msg() {
  cat <<-EOF
	Uncompress a tarball
	Usage: untar FILE [OPTIONS]
	Options:
	 -h, --help: print this message
	EOF
  exit 1
}

err_msg() {
  # Takes one argument:
  #   error message
  (>&2 echo "$1")
  exit 1
}

gpg_then_tar() {
  # Takes two arguments:
  #   path to target file
  #   tar options
  TEMP=$(basename "$1" ".gpg")
  gpg -o "$TEMP" -d "$1" || err_msg "Failed to decrypt '${1}'"
  tar "${2}" "$TEMP"
}

for i in "$@"; do
  case $i in
    -h|--help) help_msg;;
  esac
done

if [ "$#" -lt 1 ]; then
  err_msg "Usage: untar FILE [OPTIONS]"
elif ! test -f "$1"; then
  err_msg "No file '${1}'"
  exit
fi

case "$1" in
  *.tar)         tar -xvf "$1";;
  *.tar.gz)      tar -xzvf "$1";;
  *.tar.gz.gpg)  gpg_then_tar "$1" "-xzvf";;
  *.tar.bz2)     tar -xjvf "$1";;
  *.tar.bz2.gpg) gpg_then_tar "$1" "-xjvf";;
  *.tar.xz)      tar -xJvf "$1";;
  *.tar.xz.gpg)  gpg_then_tar "$1" "-xJvf";;
  *.tar.zst)     tar --zstd -xvf "$1";;
  *.tar.zst.gpg) gpg_then_tar "$1" "--zstd -xvf";;
  *)             err_msg "Not a known file extension '${1}'"
esac