configure

#!/usr/bin/env sh
# simple and flexible configure script for people who don't like to waste time
# licensed to the public domain

set -e

import=import

mkf=Makefile
objs='ytunnel.o ytdl.o'
srcs='ytunnel.d ytdl.d'

makefile='
PREFIX    = /usr/local
MANPREFIX = ${PREFIX}/man

DC      = ${_DC}
CFLAGS  = ${_CFLAGS} -wi
OBJS    = ${_OBJS}

all: ytunnel

ytunnel: ${OBJS}
	${DC} ${LDFLAGS} -of=$@ ${OBJS}

.SUFFIXES: .d .o

.d.o:
	${DC} ${CFLAGS} -c $<

clean:
	rm -f ytunnel ${OBJS}

install: ytunnel
	mkdir -p ${DESTDIR}${PREFIX}/bin
	mkdir -p ${DESTDIR}${MANPREFIX}/man1
	install -m755 ytunnel ${DESTDIR}${PREFIX}/bin/ytunnel
	cp -f ytunnel.1 ${DESTDIR}${MANPREFIX}/man1

.PHONY: all clean install
'

# utility functions

present () {
	command -v "$1" 1>/dev/null 2>/dev/null
}
using () {
	>&2 printf "using $1\n"
}
error () {
	>&2 printf "$(basename $0): $1\n"
	exit 1
}

# generators

## D compiler
gen_DC () {
	if ! [ -z "$dc" ]; then
		using "$dc"
		return 0
	fi
	if present ldc2; then
		dc=ldc2
	elif present dmd; then
		dc=dmd
	else
		error "D compiler not found; install ldc or dmd"
	fi

	using "$dc"
}

## flags used in the compilation step
gen_CFLAGS () {
	if [ -z "$debug" ]; then
		case "$dc" in
			ldc2) cflags="-Oz";;
			 dmd) cflags="-O";;
		 esac
	else
		cflags="-g"
		case "$dc" in
			ldc2) cflags="$cflags -O0 -d-debug";;
			 dmd) cflags="$cflags -debug";;
		esac
	fi

	for flag in $cflags; do
		using "$flag"
	done
}

## flags used in the linking step
gen_LDFLAGS () {
	if [ "$dc" = ldc2 ]; then
		if present ld.lld; then
			ldflags="-linker=lld"
		elif present ld.gold; then
			ldflags="-linker=gold"
		fi
	fi
	if [ -z "$debug" ]; then
		if ! [ -z "$ldflags" ]; then ldflags="$ldflags "; fi
		ldflags="$ldflags-L--gc-sections"
	fi

	for flag in $ldflags; do
		using "$flag"
	done
}

# command line interface

while getopts c:dhr ch; do
	case "$ch" in
		c)
			case "$OPTARG" in
				ldc2) dc="ldc2" ;;
				dmd)  dc="dmd"  ;;
				*) error "unknown D compiler '$OPTARG' specified (valid options: ldc2, dmd)" ;;
			esac
			;;
		d) debug=1 ;;
		r) unset debug ;;
		h)
			cat <<EOF
configure: create an optimised makefile for the current environment

options:
  -c: force use of a particular compiler (dmd or ldc2)
  -d: build in debug mode, with debug symbols and statements enabled
  -r: build in release mode with optimisation flags enabled (default)
  -h: show this help message
EOF
			exit 0
			;;
		?) exit 1 ;;
		:) exit 1 ;;
	esac
done

# creating the makefile

u_cflags="$cflags"
unset cflags

gen_DC
gen_CFLAGS
gen_LDFLAGS

rm -f "$mkf"
printf '# begin generated definitions' >>"$mkf"
printf '
_DC = %s
_CFLAGS = %s
_LDFLAGS = %s
'              \
	"$dc"      \
	"$u_cflags $cflags" \
	"$ldflags" \
		>>"$mkf"
## generate obj list
printf '_OBJS =' >>"$mkf"
for obj in $objs; do
	printf " $obj" >>"$mkf"
done
printf '\n' >>"$mkf"
printf '# end generated definitions\n' >>"$mkf"

printf "$makefile" >>"$mkf"

## generate dependency list
>&2 printf "generating dependency list\n"
printf '\n# begin generated dependencies\n' >>"$mkf"
i=1
for obj in $objs; do
	"$dc" $u_cflags -O0 -o- -makedeps \
		"$(printf "$srcs" | awk '{print $'"$i"'}')" >>"$mkf"
	i="$(($i + 1))"
done
printf '# end generated dependencies\n' >>"$mkf"