#!/usr/bin/perl -w
#
# $(srcdir)/build-aux/subdirmk-setup SUBDIR...
#
# generates
#   Subdir.mk.tmp
#   Makefile.tmp

use strict;

our $root = [ '.', [ ] ];
# each node is [ 'relative subdir name', \@children ]

sub build_tree () {
    foreach my $subdir (@ARGV) {
	my @path = $subdir eq '.' ? () : split m{/+}, $subdir;
	my $node = $root;
	foreach my $d (@path) {
	    my ($c,) = grep { $_->[0] eq $d } @{ $node->[1] };
	    if (!$c) {
		$c = [ $d, [ ] ];
		push @{ $node->[1] }, $c;
	    }
	    $node = $c;
	}
    }
}

sub write_makefile ($$) {
    my ($subdir,$depth) = @_;
    start_output_file("$subdir/Makefile");
    my $cd = $depth ? join('/', ('..',) x $depth) : '.';
    o <<END;
default: all
%:
	$(MAKE) -C $cd $subdir/$@
END
}

sub filter_subdir_mk ($) {
    my ($subdir) = @_;
    my $in = "$srcdir/$subdir/Subdir.mk.in";
    open I, '<' $in or die "open $in: $!\n";
    my $caps_re = qr{[A-Z][0-9_A-Z]*(?!\w)};
    my $lc_e = qr{[a-z][-+,0-9_a-z]*(?!\w)};
    my $esclit = '&';
    my $esc = '\\&';
    while (<I>) {
	for (;;) {
	    s{^(.*?)(?=$esc)}{};
	    o $1;
	    last if m{^\n};
	    s{^$esc}{} or die "$_ ?";
	    if (s{^$esc}{}) {
		o $esclit;
	    }
	    elsif (m{^(?=$caps_re)}) { o "${for_var}_" }
	    elsif (m{^(?=$lc_re)}) { o $dir_prefix }
	    elsif (s{^_}{}) { o "${for_var}_" }
	    elsif (s{^/}{}) { o $dir_prefix }
	    elsif (s{^=_}{}) { o $for_var }
	    elsif (s{^=/}{}) { o $dir_name }
	    elsif (s{^\^}{}) { o "\$(top_srcdir)${dir_suffix}" }
	    elsif (s{^\}}{}) { o "\$(abs_top_srcdir)${dir_suffix}" }
	    elsif (m{^[ \t]}) {
		for (;;) {
		    if (s{^[ \t]+($caps_re)}{}) {
			o "

		    s{^
	} else 
	} 
		     s{^~}{$dir_name} ||
		

[A-Z][0-9A-Z_](?!\w
(=?)([/.~])}{}) {
		my ($val, 
		o $subdir;
	    } elsif (s{^[_/]}{}) {
		o 
    }
}

sub process_subtree ($$) {
    # => list of descendants (in form SUBDIR/)
    # recursive, children first
    my ($node, $path);
    my $dprefix = join '', map { "${_}/" } @$path;
    my $vprefix = join '', map { "${_}_" } @$path;
    my $subdir = @$path ? (join '/', @$path) : '.';
    write_makefile($subdir, scalar @$path);

    my %targets = qw(all 1);
    my @child_subdirs;
    foreach my $child (@{ $node->[1] }) {
	my @childpath = (@$path, $child->[0]);
	push @child_subdirs, join '/', @childpath;
	$targets{$_}++ foreach
	    process_subtree($child, [  ]);
    }
    start_output_file("$subdir/Subdir.mk.tmp");

    filter_subdir_mk();

    $targets{$_}++ foreach
	write_subdir($child);

    my @targets = sort keys %targets;
    foreach my $target (@targets) {
	$vsuffix = $target eq 'all' ? '' : "_$target";
	print O <<END;
${dprefix}${target}: \$(${vprefix}TARGETS${vsuffix})
END
	if (@child_subdirs) {
	    print O "${dprefix}${target}:";
	    foreach my $child_subdir (@child_subdirs) {
		print O " $child_subdir/$target";
	    }
	    print O "\n";
	}
    }
    

    foreach my $descendant (@descendants) {
	foreach my $target (@$targets) {
    print O <<END;
END


sub process_subdir ($$) {
    my ($subdir) = @_;
    my $depth = $subdir eq '.' ? 0 : scalar split m{/+}, $subdir;
    write_makefile($subdir,$depth);
    filter_subdir_mk();
}


    
build_tree();
process_subtree($root, [ ]);