#!/bin/bash

set -e
#set -x

PROGNAME="$0"
BOLD=$(tput bold)
RST=$(tput sgr0)

file=
config_file="/etc/lrpb.conf"
declare -A config=()
command=

die() {
    echoerr "error: $@"
    exit 1
}

echoerr() {
	>&2 echo "$@"
}

usage() {
	cat <<EOF
usage: $PROGNAME OPTIONS COMMAND

Options:
    -c|--config FILE   path to config file (default: $config_file)
    -f|--file FILE     path to script
	-x                 set -x

Commands:
    upload
    exec
EOF
	exit 1
}

installed() {
	command -v "$1" > /dev/null
	return $?
}

download() {
	local source="$1"
	local target="$2"

	if installed curl; then
		curl -f -s -o "$target" "$source"
	elif installed wget; then
		wget -q -O "$target" "$source"
	else
		die "neither curl nor wget found, can't proceed"
	fi
}

signify() {
	"${config[signify_path]}" "$@"
}

read_config() {
	local n=0
	local failed=

	while read line; do
		n=$(( n+1 ))

		# skip empty lines or comments
		if [ -z "$line" ] || [[ "$line" =~ ^#.*  ]]; then
			continue
		fi

		if [[ $line = *"="* ]]; then
			config[${line%%=*}]=${line#*=}
		else
			echoerr "config: invalid line $n"
			failed=1
		fi
	done < <(cat "$config_file")

	[ -z "$failed" ] || exit 1
}

check_config() {
	local failed=

	for key in $1; do
		if [ -z "${config[$key]}" ]; then
			echoerr "config: ${BOLD}${key}${RST} is missing"
			failed=1
		fi
	done

	[ -z "$failed" ] || exit 1
}

delete_unpacked_script() {
	local path=
	for f in script.sh script.sh.sig; do 
		path="${config[cwd]}/$f"
		if [ -f "$path" ]; then rm "$path"; fi
	done
}

do_upload() {
	local file="$1"
	local dir=$(mktemp -d)

	pushd "$dir" >/dev/null
	cp "$file" .

	local bname="$(basename "$file")"

	signify -S -s "${config[seckey_path]}" -m "$bname" || \
		die "signify failed: $?"

	local archive="${config[name]}.tar.gz"

	tar --owner=0 --group=0 \
		--transform="flags=r;s|$bname|script.sh|" \
		--transform="flags=r;s|$bname.sig|script.sh.sig|" \
		-czf "$archive" "$bname" "$bname.sig" >/dev/null

	rsync -p --chmod=u+rw,g+r,o+r -e "ssh -p${config[upload_port]}" \
		$archive \
		"${config[upload_user]}"@"${config[upload_host]}":"${config[upload_path]}" || \
		die "rsync failed: $?"

	popd >/dev/null
	rm -rf "$dir"
}

do_exec() {
	pushd "${config[cwd]}" >/dev/null || die "failed to change to ${config[cwd]}"

	local archive="${config[name]}.tar.gz"
	download "${config[url]}$archive" "$archive" || exit 0

	local checksum
	local same=0
	local f

	checksum=$(md5sum "$archive" | awk '{print $1}')
	if [ -f "${config[cache_file]}" ] && [ "$(cat "${config[cache_file]}")" = "$checksum" ]; then
		same=1
	fi

	if [ "$same" = "0" ]; then
		delete_unpacked_script
		tar --no-same-owner -xzf "$archive"
		
		signify -V -p "${config[pubkey_path]}" -m script.sh >/dev/null || die "signify failed: $?"
		echo "$checksum" > "${config[cache_file]}"

		chmod +x script.sh
		sh script.sh || echoerr "script.sh exited with $?"
	else
		echoerr "archive have not changed, skipping"
	fi
		
	rm "$archive"
	delete_unpacked_script

	popd >/dev/null
}

case $BASH_VERSION in
  ''|[0-3].*)
	  die "bash 4.0 is required"
	  ;;
esac

[[ $# -lt 1 ]] && usage

while [[ $# -gt 0 ]]; do
	case $1 in
		upload|exec)
			command="$1"
			shift
			;;

		-c|--config)
			config_file="$2"
			shift; shift
			;;

		-f|--file)
			file="$2"
			shift; shift
			;;

		-x)
			set -x
			shift
			;;

		*)
			die "unrecognized option $1"
			exit 1
			;;
	esac
done

[ -z "$config_file" ] && die "config is not specied"
[ -f "$config_file" ] || die "config file (${BOLD}${config}${RST}) not found"
read_config

[ -z "$command" ] && die "command not specified"
case "$command" in
	upload)
		[ -z "$file" ] && die "file is not specified"
		check_config "upload_host upload_port upload_user upload_path name signify_path seckey_path"
		do_upload "$(realpath "$file")"
		;;

	exec)
		check_config "url name pubkey_path signify_path cwd cache_file"
		[ -d "${config[cwd]}" ] || die "invalid ${BOLD}cwd${RST}: no such directory"
		do_exec
		;;

	*)
		die "invalid command '$command'"
		;;
esac