#!/bin/sh

set -e

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

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

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

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

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

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

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

	EOF
}

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

	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

standard_c=
posix=
xopen=

while getopts hc:p: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})		;;

	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

printf 'Building C library for %d-bit %s conforming to:\n' "${wordsize}" "${architecture}"
printf 'ISO C:  %d\n' ${standard_c}
test -n "${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=\$(TOPDIR)/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

if [ -n "${xopen}" ]; then
	if [ $xopen -eq 400 ]; then
		printf 'CFLAGS=-D_XOPEN_SOURCE -D_XOPEN_SOURCE_EXTENDED=1\n' >> .config.mk
	else
		printf 'CFLAGS=-D_XOPEN_SOURCE=%d\n' "${xopen}" >> .config.mk
	fi
elif [ -n "${posix}" ]; then
	printf 'CFLAGS=-D_POSIX_C_SOURCE=%d\n' "${posix}" >> .config.mk
fi


### generate .build.mk
cat <<EOF > .build.mk
.POSIX:

# work-around GNU ar's default "deterministic" mode
ARFLAGS=rvU

default: all

include .config.mk
include \$(TOPDIR)/.deps.mk

EOF

rm -f .build.all.mk

for lib in $(ls $(dirname $0)/.deps/lib* | sed -e 's#^.*/\(lib.*\)\..*$#\1#g' | grep -v '\.h$' | sort -u); do
	printf '%s.a:' "${lib}"

	for cver in $(ls $(dirname $0)/.deps/${lib}.C_* 2>/dev/null | sed -e 's#^.*\.C_##g'); do
		if [ $cver -le ${standard_c:-1} ]; then
			printf ' $(%s_C_%d_OBJS)' "${lib}" "${cver}"
			printf '%s\n' "${lib}" >> .build.all.mk
		fi
	done

	for pver in $(ls $(dirname $0)/.deps/${lib}.POSIX_* 2>/dev/null | sed -e 's#^.*\.POSIX_##g'); do
		if [ $pver -le ${posix:-0} ]; then
			printf ' $(%s_POSIX_%d_OBJS)' "${lib}" "${pver}"
			printf '%s\n' "${lib}" >> .build.all.mk
		fi
	done

	for xver in $(ls $(dirname $0)/.deps/${lib}.XOPEN_* 2>/dev/null | sed -e 's#^.*\.XOPEN_##g'); do
		if [ $xver -le ${xopen:-0} ]; then
			printf ' $(%s_XOPEN_%d_OBJS)' "${lib}" "${xver}"
			printf '%s\n' "${lib}" >> .build.all.mk
		fi
	done

	printf '\n\t$(AR) $(ARFLAGS) $@ $?\n\n'
done >> .build.mk

printf 'all:' >> .build.mk
sort -u .build.all.mk | awk '{printf(" %s.a", $0);}' >> .build.mk
printf '\n' >> .build.mk
rm -f .build.all.mk

for i in $libs; do
	echo $i
done >> .build.mk

### generate main Makefile
### FIXME: this can probably be kept as a fixed file
cat <<EOF > Makefile
.POSIX:
.DEFAULT:;\$(MAKE) all

include .config.mk

all: \$(TOPDIR)/.deps.mk \$(INCDIR)
	@mkdir -p \$(OBJDIR)
	\$(MAKE) -f .build.mk

deps: \$(TOPDIR)/.headers.mk \$(TOPDIR)/.deps.mk

\$(TOPDIR)/.deps.mk: \$(TOPDIR)/mk.sh
	sh -c '. \$(TOPDIR)/mk.sh; cd \$(TOPDIR); make_deps_mk'

\$(TOPDIR)/.headers.mk: \$(TOPDIR)/mk.sh
	sh -c '. \$(TOPDIR)/mk.sh; cd \$(TOPDIR); make_headers_mk'

headers \$(INCDIR): \$(TOPDIR)/.headers.mk \$(TOPDIR)/mkh.sh
	\$(MAKE) -f \$(TOPDIR)/.headers.mk headers

ctags:
	ctags \$\$(find src -name \*.c)

clean:
	rm -rf \$(OBJDIR) *.a

extra-clean: clean
	rm -rf .deps .deps.mk .headers.mk \$(INCDIR)
EOF