#!/bin/sh

prefix=/usr/local

ismac() {
	uname -s | grep Darwin >/dev/null
}

isx86_64() {
	uname -m | grep -i X86_64 >/dev/null
}

isbsd() {
	uname -s | grep BSD >/dev/null
}

isopenbsd() {
	uname -s | grep OpenBSD >/dev/null
}

usage() {
	echo "supported arguments"
	echo "--prefix=/path 		default: $prefix"
	echo "--exec_prefix=/path	default: $prefix/bin"
	echo "--bindir=/path		default: $prefix/bin"
	echo "--libdir=/path		default: $prefix/lib"
	echo "--includedir=/path	default: $prefix/include"
	echo "--sysconfdir=/path	default: $prefix/etc"
	ismac && isx86_64 && echo "--fat-binary : build for both i386 and x86_64 architectures on 64-bit Macs"
	echo "--help : show this text"
	exit 1
}

spliteq() {
	arg=$1
	echo "${arg#*=}"
	#alternatives echo "$arg" | cut -d= -f2-
	# or echo "$arg" | sed 's/[^=]*=//'
}

fat_binary=

parsearg() {
	case "$1" in
	--prefix=*) prefix=`spliteq $1`;;
	--exec_prefix=*) exec_prefix=`spliteq $1`;;
	--bindir=*) bindir=`spliteq $1`;;
	--libdir=*) libdir=`spliteq $1`;;
	--includedir=*) includedir=`spliteq $1`;;
	--sysconfdir=*) sysconfdir=`spliteq $1`;;
	--fat-binary) fat_binary=1;;
	--help) usage;;
	esac
}

while true ; do
	case $1 in
	-*) parsearg "$1"; shift;;
	*) break ;;
	esac
done

if [ -z "$exec_prefix" ] ; then
	exec_prefix=$prefix
fi

if [ -z "$libdir" ] ; then
	libdir=$prefix/lib
fi

if [ -z "$includedir" ] ; then
	includedir=$prefix/include
fi

if [ -z "$sysconfdir" ] ; then
	sysconfdir=$prefix/etc
fi

if [ -z "$bindir" ] ; then
	bindir=$exec_prefix/bin
fi

if [ -z "$CC" ] ; then
	CC=cc
fi

echo CC?=$CC>config.mak
[ -z "$CPPFLAGS" ] || echo CPPFLAGS?=$CPPFLAGS>>config.mak
[ -z "$CFLAGS" ] || echo USER_CFLAGS?=$CFLAGS>>config.mak
[ -z "$LDFLAGS" ] || echo USER_LDFLAGS?=$LDFLAGS>>config.mak
echo prefix=$prefix>>config.mak
echo exec_prefix=$exec_prefix>>config.mak
echo bindir=$bindir>>config.mak
echo libdir=$libdir>>config.mak
echo includedir=$includedir>>config.mak
echo sysconfdir=$sysconfdir>>config.mak
make_cmd=make
if ismac ; then
	echo NO_AS_NEEDED=>>config.mak
	echo LDSO_SUFFIX=dylib>>config.mak
	echo MAC_CFLAGS+=-DIS_MAC=1>>config.mak
	if isx86_64 && [ "$fat_binary" = 1 ] ; then
		echo "Configuring a fat binary for i386 and x86_64"
		echo MAC_CFLAGS+=-arch i386 -arch x86_64>>config.mak
		echo LDFLAGS+=-arch i386 -arch x86_64>>config.mak
	fi
	echo LD_SET_SONAME=-Wl,-install_name,>>config.mak
elif isbsd ; then
	echo LIBDL=>>config.mak
	echo "CFLAGS+=-DIS_BSD">>config.mak
	isopenbsd && echo "CFLAGS+=-DIS_OPENBSD">>config.mak
	make_cmd=gmake
fi

echo "Done, now run $make_cmd && $make_cmd install"