#!/bin/sh
set -eu

cflags() {
	echo "CFLAGS += $*"
}
ldlibs() {
	echo "LDLIBS ${o:-}= $*"
	o=+
}
config() {
	pkg-config --print-errors "$@"
	cflags $(pkg-config --cflags "$@")
	ldlibs $(pkg-config --libs "$@")
}
defstr() {
	cflags "-D'$1=\"$2\"'"
}
defvar() {
	defstr "$1" "$(pkg-config --variable=$3 $2)${4:-}"
}

exec >config.mk

for opt; do
	case "${opt}" in
		(--prefix=*) echo "PREFIX = ${opt#*=}" ;;
		(--mandir=*) echo "MANDIR = ${opt#*=}" ;;
		(*) echo "warning: unsupported option ${opt}" >&2 ;;
	esac
done

case "$(uname)" in
	(OpenBSD)
		cflags -I/usr/local/include
		ldlibs -L/usr/local/lib -liconv -ltls
		;;
	(Darwin)
		config libtls
		ldlibs -liconv -lresolv
		;;
	(Linux)
		cflags -D_GNU_SOURCE
		ldlibs -lresolv
		config libtls
		echo 'OBJS += compat.o'
		;;
	(*)
		config libtls
		;;
esac