#!/bin/sh

set -e

CONFIGDIR="$(dirname $0)/mk"

show_help() {
	cat <<-EOF
	usage: ./configure [options...]

	Options:
	   -d		Enable debugging symbols and asserts

	   -I dir	Set the directory to use for #include files

	   -a arch	Choose the underlying architecture to build for:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/architecture.conf)

	   -c version	Conform to:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/c.conf)

	   -p version	Conform to:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/posix.conf)

	   -w wordsize	Choose a word size for the architecuture:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/wordsize.conf)

	   -x version	Conform to:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/xopen.conf)

	   -X number	Enable C Extension:
	$(awk '{ printf("\t%s\n", $0); }' ${CONFIGDIR}/cext.conf)

	EOF
}

validate_option() {
	option="${CONFIGDIR}/$1.conf"

	for opt in $(awk '/^[0-9]/ { print $1 }' "${option}"); do
		if [ "$2" = "${opt}" ]; then
			echo "$2"
			return 0
		fi
	done

	printf 'Invalid option '%s'. Valid options are:\n' "$2" >&2
	cat "${option}" >&2
	exit 1
}

option=

architecture=x86
wordsize=64
debug=0
include=

standard_c=
posix=
xopen=
cext=

while getopts dhc:p:x:I:X: option; do
	case ${option} in
	a)	architecture=$(validate_option architecture ${OPTARG})	;;
	c)	standard_c=$(validate_option c ${OPTARG})		;;
	p)	posix=$(validate_option posix ${OPTARG})		;;
	w)	wordsize=$(validate_option wordsize ${OPTARG})		;;
	x)	xopen=$(validate_option xopen ${OPTARG})		;;
	X)	cext=$(validate_option cext ${OPTARG})			;;
	I)	include=${OPTARG}					;;
	d)	debug=1 ;;

	h)	show_help
		exit 0
		;;

	?)	printf 'Unknown option "%c". Try "-h" for help.\n' $option
		exit 1
		;;
	esac
done

if [ -z "${standard_c}" ] && [ -z "${posix}" ] && [ -z "${xopen}" ]; then
	xopen=700
fi

if [ -n "${posix}" ] && [ -n "${xopen}" ]; then
	printf 'Specify only one of "-x" or "-p".\n'
	exit 1
fi

if [ -n "${xopen}" ]; then
	if [ $xopen -eq 700 ]; then
		posix=200809
	elif [ $xopen -eq 600 ]; then
		posix=200112
	elif [ $xopen -eq 500 ]; then
		posix=199506
	else
		posix=2
	fi
fi

if [ -z "${standard_c}" ] && [ -n "${posix}" ]; then
	if [ $posix -ge 200112 ]; then
		standard_c=199901
	else
		standard_c=1
	fi
fi

if [ ${posix:-0} -ge 200112 ] && [ $standard_c -lt 199901 ]; then
	printf 'POSIX.1-2001 and newer require C99 or newer.\n'
	exit 1
fi

if [ -n "${cext}" ] && [ ${standard_c:-1} -lt 201112 ]; then
	printf 'C Extension 1 requires at least C11.\n'
	exit 1
fi

printf 'Building C library for %d-bit %s conforming to:\n' "${wordsize}" "${architecture}"
printf 'ISO C:  %d' ${standard_c}
test -n "${cext}"  && printf ' (Extensions: %s)' ${cext}
printf '\n'
test -n "${posix}" && printf 'POSIX:  %d\n' ${posix}
test -n "${xopen}" && printf 'X/OPEN: %d\n' ${xopen}

cat <<-EOF > .config.mk
	.POSIX:

	ARCHITECTURE=${architecture}
	WORDSIZE=${wordsize}
	TOPDIR=$(dirname $0)
	SRCDIR=\$(TOPDIR)/src
	INCDIR=${include}
	OBJDIR=./obj

EOF

if [ ${standard_c:-1} -lt 199901 ]; then
	printf 'CC=c89\n' >> .config.mk
else
	printf 'CC=c%02d\n' $(( (standard_c / 100) % 100 )) >> .config.mk
fi

CFLAGS="${CFLAGS}"

if [ $debug -eq 1 ]; then
	CFLAGS="${CFLAGS} -g"
else
	CFLAGS="${CFLAGS} -DNDEBUG"
fi

if [ -n "${xopen}" ]; then
	if [ $xopen -eq 400 ]; then
		CFLAGS="${CFLAGS} -D_XOPEN_SOURCE -D_XOPEN_SOURCE_EXTENDED=1"
	else
		CFLAGS="${CFLAGS} -D_XOPEN_SOURCE=${xopen}"
	fi
elif [ -n "${posix}" ]; then
	CFLAGS="${CFLAGS} -D_POSIX_C_SOURCE=${posix}"
fi

printf 'CFLAGS=$(BASE_CFLAGS) %s\n\n' "${CFLAGS}" >> .config.mk

#
# TODO: C extentsion
#
for lib in $(cat $(dirname $0)/mk/*.d | grep 'lib.*_[CPX]\.' | cut -d: -f1 | sort -u); do
	ver=$(echo $lib | cut -d. -f2)
	if (echo $lib | grep -q _C) && [ "$ver" -le ${standard_c:-1} ]; then
		printf 'all: %s\n' $lib >> .config.mk
	elif (echo $lib | grep -q _P) && [ "$ver" -le ${posix:-0} ]; then
		printf 'all: %s\n' $lib >> .config.mk
	elif (echo $lib | grep -q _X) && [ "$ver" -le ${xopen:-0} ]; then
		printf 'all: %s\n' $lib >> .config.mk
	fi
done

### generate main Makefile
if ! [ -f Makefile ]; then
	cp "$(dirname $0)/Makefile" .
fi