#!/bin/sh
#
# Kconfig preprocessor
#
# Copyright (C) 2014  Patrick "P. J." McDermott
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

set -u

main()
{
	local script=
	local arg=
	local var=
	local val=

	if [ ${#} -lt 1 ]; then
		usage >&2
		exit 1
	fi

	script=''
	for arg in "${@}"; do
		case "${arg}" in
			*=*)
				IFS='=' read var val <<-EOF
					${arg}
					EOF
				val="$(printf '%s' "${val}" | sed 's|/|\\/|g')"
				script="${script}s/\$${var}/${val}/g;"
				shift 1
				;;
			*)
				break
		esac
	done

	if [ ${#} -ne 1 ]; then
		usage >&2
		exit 1
	fi

	cd "$(dirname "${1}")"
	parse "${1}" "${script}"
}

usage()
{
	printf 'Usage: %s [<var>=<val> ...] <kconfig-file>\n' "${0}"
}

parse()
{
	local file="${1}"
	local script="${2}"
	local line=

	while IFS='' read line; do
		if [ "x${line}" != "x${line#source}" ]; then
			line="$(printf '%s' "${line}" | \
				sed 's/^source[ \t][ \t]*"*\([^"]*\).*$/\1/')"
			parse "${line}" "${script}"
		else
			printf '%s\n' "${line}"
		fi
	done <<-EOF
		$(sed "${script}" <"${file}")
		EOF
}

main "${@}"