#!/bin/sh -e
#
# arc - a directory archiver with compression
#
# https://romanzolotarev.com/bin/arc
# Copyright 2018-2019 Roman Zolotarev <hi@romanzolotarev.com>
#

fail() { >&2 echo "$@" exit 1; }
usage() { fail "usage: ${0##*/} <src> <archive>"; }

test -z "$1" && usage
test -z "$2" && usage

src=$(readlink -f "$1")
arch="$2"
tree="${arch}.tree.gz"
dgst="${arch}.tree.sha256"

test -d "$src" || fail "$src: no directory"
test -e "$arch" && fail "$arch: exists"
test -e "$tree" && fail "$tree: exists"
test -e "$dgst" && fail "$dgst: exists"

# print out $src, its file size and archive's file name
printf '%s %s %s ' "$src" "$(du -sh "$src"|cut -f1)" "$arch"

# generate the spec file with sha256 hashes for every file
# archive it and generate sha256 hash for the spec itself
mtree -cK sha256digest -p "$src" | gzip   > "$tree"
zcat "$tree"                     | sha256 > "$dgst"

cd "$src" || fail "$src: no directory"

# write (-w) gzipped (-z) archive
# in cpio format (-x cpio)
# to the file (-f)
pax -wzx cpio -f "$arch" .
	# TODO
	#
	# to exclude '.*/foo/.*' and '.*bar.*'
	#
	# -'s,.*/foo/.*,,' \
	# -'s,.*bar.*,,' \

# print out the archive file size
du -sh "$arch" |
cut -f1