#!/bin/sh
PROGNAME="${0##*/}"

if [ "$1" = "-h"  ] || [ "$1" = "--help" ] ; then
	cat <<-EOF
		Usage: ${PROGNAME}: [ <input_file> ] [ <output_file> ]

		This script takes an Asterisk makeopts file, or any file containing
		"make" style variable assignments, and converts it into a format
		that can be directly 'sourced' by shell scripts.

		* Any spaces around the equals sign are removed.
		* The variable value is quoted.
		* The "make" "or" command is evaluated.

		Both input and output files are optional and will default to
		stdin and stdout respectively.

		NOTE: This script relies on NO external commands and only POSIX
		constructs.  It should be runnable by any shell.
	EOF
	exit 1
fi

input_file="/dev/stdin"
if [ "$1" != "" ] ; then
	input_file="$1"
fi

output_file="/dev/stdout"
if [ "$2" != "" ] ; then
	output_file="$2"
fi

# orfunc is a code fragment to be added to the outp[ut file.
# We don't WANT the variables evaluated.
# shellcheck disable=SC2016
orfunc='or (){ before="${1%,*}" ; after="${1#*,}" ; if [ "$before" = "" ] ; then echo "${after}" ; else echo "${before}" ; fi ; }'
echo "${orfunc}" >"${output_file}"

while read -r LINE ; do
	var="${LINE%%=*}"
	if [ "${var}" != "" ] ; then
		val="${LINE#*=}"
		if [ "${val}" != "${var}" ] ; then
			if [ "${val%% *}" = "" ] ; then
				echo "${var% *}=\"${val#* }\""
			else
				echo "${var% *}=\"${val}\""
			fi
		fi
	fi
done <"${input_file}"  >>"${output_file}"