#!/bin/bash
#
# ghcdeps: generate Haskell make dependencies for compiling with GHC.
#
# Copyright (c) 2015-2018 Rudy Matela.
# Distributed under the 3-Clause BSD licence.
#
# From a list of files provided on standard input,
# generate flat make dependencies.
#
# Transitive relations are repeated.
#
# Usage:
#   $ ghcdeps -isomedir:someother <<LIST
#   program.hs
#   Library.hs
#   Path/To/Library.hs
#   LIST
#   program: ...
#   Library.o: ...
#   Path/To/Library.o: ...
#
# Or:
#   $ find -name \*.hs -o -name \*.lhs | ghcdeps [GHCFLAGS]
#   ...
#
# Note that when using find, you have to remember to exclude unecessary files,
# e.g.:  dist, Setup.hs
#
# Yes, this is hacky.  But hey, it works.
while read fn
do
	ghc "$@" -dep-suffix=. -dep-makefile=tmp.mk -M "$fn" ||
	exit 1
	deps="`cat tmp.mk |
	       grep "hs$" |
	       sort |
	       sed -e "s/.*: //" |
	       tac |
	       tr '\n' ' ' |
	       sed -e "s/ $//"`"
	obj=`echo $fn | sed -e 's,^\./,,;s/\.hs$/.o/'`
	bin=`echo $fn | sed -e 's,^\./,,;s/\.hs$//'`
	echo "$obj: $deps"
	grep -q "main" "$fn" && echo "$bin: `echo $deps | sed -e 's|[^ ]*src[^ ]*||g'` mk/toplibs"
	rm -f tmp.mk
done |
sort |
sed -e 's,  *, \\\n  ,g'