#!/bin/bash

libs=(luajit sdl2 pangoft2)
CFLAGS+=(-std=c11 -fPIC)
LDFLAGS+=(-shared)

usage () { echo "Usage: $0 [-h|options...]"; }

help () {
	cat <<EOF
Options:
  -B ldlib    Append ldlib to LDLIBS
  -C cflag    Append cflag to CFLAGS
  -L ldflag   Append ldflag to LDFLAGS
  -P cppflag  Append cppflag to CPPFLAGS
  -c when     Enable compiler colours (always|auto|off) [default: auto]
  -d          Enable debugging flags
  -e          Enable -Werror
  -h          Show this help
  -o          Enable optimisation flags
  -v          Print results of configuration
  -w          Enable warning flags
Environment:
  CC          C compiler
  PKG_CONFIG  pkg-config
EOF
}

exists() { command -v "$1" >/dev/null 2>&1; }

check() {
	what=$1
	shift
	for p do
		if exists "$p"; then
			echo "$p"
			return
		fi
	done
	echo "$what not set or found" >&2
	return 1
}

CC=$(check '$CC, cc, gcc or clang' "$CC" cc gcc clang) || exit
pc=$(check '$PKG_CONFIG, pkg-config or pkg-conf' "$PKG_CONFIG" pkg-config pkg-conf) || exit

for l in "${libs[@]}"; do
	"$pc" --print-errors --exists "$l" || exit
done
CFLAGS+=($("$pc" --cflags-only-other "${libs[@]}"))
CPPFLAGS+=($("$pc" --cflags-only-I "${libs[@]}"))
LDFLAGS+=($("$pc" --libs-only-L --libs-only-other "${libs[@]}"))
LDLIBS+=($("$pc" --libs-only-l "${libs[@]}"))

colour=auto
while getopts B:C:L:P:c:dehovw opt; do
	case $opt in
	B) LDLIBS+=("$OPTARG");;
	C) CFLAGS+=("$OPTARG");;
	L) LDFLAGS+=("$OPTARG");;
	P) CPPFLAGS+=("$OPTARG");;
	c) colour="$OPTARG";;
	d)
		CFLAGS+=(-Og -g)
		LDFLAGS+=(-Og -g)
		;;
	e) CFLAGS+=(-Werror);;
	h) usage; help; exit;;
	o)
		CFLAGS+=(-O2 -flto)
		LDFLAGS+=(-O2 -flto)
		;;
	v) verbose=1;;
	w) CFLAGS+=(-Wall -Wextra);;
	?) usage >&2; exit 1;;
	esac
done
if [[ $colour == auto && -t 1 ]]; then
	colour=always
fi
if [[ $colour == always ]]; then
	CFLAGS+=(-fdiagnostics-color)
fi

{
	echo "# generated using $0 $@"
	echo "CC=$CC"
	echo "CFLAGS=(${CFLAGS[@]@Q})"
	echo "CPPFLAGS=(${CPPFLAGS[@]@Q})"
	echo "LDFLAGS=(${LDFLAGS[@]@Q})"
	echo "LDLIBS=(${LDLIBS[@]@Q})"
} >.config.rc
[[ $verbose ]] && cat .config.rc