#!/bin/sh
set -e # strict errors
set -u # don't expand unbound variables
set -f # disable pathname expansion
set -C # noclobber
\unalias -a # no command surprises
export LC_ALL=C # no locale headaches
unset IFS # no field splitting surprises


RELPATH=${0%/*}
: RELPATH=${RELPATH:-.}

CHANGELOG=${RELPATH}/../debian/changelog
ROOTDIR=${RELPATH}/..

GIT="$(command -v git)"


changelog() {
	if [ ! -f ${CHANGELOG} ]; then
		printf -- "${CHANGELOG}: No such file\n" >&2
		exit 1
	fi

	cat ${CHANGELOG}
}


usage() {
	cat <<-EOF
	usage: ${0##*/} [-h] version|author|commit
	  -h  print this usage message

	version  most recent package version number
	author   author of most recent log message
	commit   Git hash of most recent commit

	Report bugs to <william@25thandClement.com>
	EOF
}

while getopts h OPT; do
	case "${OPT}" in
	h)
		usage
		exit 0
		;;
	*)
		usage >&2
		exit 1
		;;
	esac
done

shift $(($OPTIND - 1))


case "${1:-version}" in
version)
	changelog | sed -ne '
		s/.*(\([1-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\).*).*/\1/
		t Found
		d
		:Found
		p
		q
	'
	;;
author)
	changelog | sed -ne '
		s/.*<\([^>]*@[^>]*\)>.*/\1/
		t Found
		d
		:Found
		p
		q
	'
	;;
commit)
	test -n "${GIT}" -a -d ${ROOTDIR}/.git || exit 1

	cd ${ROOTDIR}
	${GIT} show --pretty='%H' HEAD 2>/dev/null | sed -n '1p'
	;;
*)
	usage >&2
	exit 1
	;;
esac

exit 0