#!/usr/bin/perl
# mkmam: make Makefile.am from Makefile.am.in,
# substituting file lists into _SOURCES variables

#   Copyright (C) 2005 by ott
#   Part of the Battle for Wesnoth Project http://wesnoth.org/
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License.
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY.
#
#   See the COPYING file for more details.

# Automake is dysfunctional: it doesn't understand
# that one may want to use a list of sources for multiple projects,
# and that this list should be clean and simple...
# The automake authors seem to think one should extract the list of sources
# from the Makefile.am _SOURCES variable if one needs it.
# This script works around this limitation by substituting any
# occurrences of @NAME@ inside any _SOURCES variable assignments
# in FILE.in with the contents of the file NAME, and writes FILE as the output.
# It is assumed that NAME contains a list of files, one per line
# and multiple files can be substituted at once.
# Watch out for @ substitutions inside file NAME, no check is made
# for infinite loops -- it's probably best to avoid @ inside the NAME files.

use strict;
use File::Basename;

my $DEBUG = 0;
my $filename;

sub process_arg {
    # uses global $filename
    my $arg = shift;
    $DEBUG and print STDERR "argument :$arg:\n";
    while (1) { # process $arg
	my $i = index($arg, '@');
	my $l = index($arg, '@', $i+1) - $i + 1;
	last if $l <= 1; # stop unless we find two @'s
	# now $l > 1 and substr($arg, $i, $l) =~ /^@.*@$/
	my $thisfile = substr($arg, $i, $l, '');
	$thisfile =~ s/^@([^@]*)@/\1/;
	my ($base,$path,$type) = fileparse($filename, '');
	$thisfile = (fileparse($filename, ''))[1] . $thisfile unless $thisfile =~ /^\//;
	$DEBUG and print STDERR "substituting $thisfile\n";
	substr($arg, $i, 0) = `cat $thisfile`;
    }
    $arg =~ s/^([^\\])/\\\n\1/;
    $arg =~ s/([^\\\n ])\n/\1 \\\n/g;
    $arg =~ s/\n +/\n\t/g;
    $arg =~ s/\n([^\t\n])/\n\t\1/g;
    $arg =~ s/\s*\\(\n+)$/\1/;
    $DEBUG and print STDERR "argument now :$arg:\n";
    return $arg;
}

my $state;
my $arg;

Argument:
while ($filename = shift) {
    $DEBUG and print STDERR "opening $filename for reading\n";
    if (! open(CURRENT, $filename)) {
        warn("cannot open file $filename, skipping");
        next Argument;
    }
    my ($base,$path,$type) = fileparse($filename, qr{\.in});
    if ($type ne '.in') {
	warn "Can only process files ending with .in, skipping $filename";
	next Argument;
    }
    my $outfile = $path . $base;
    $DEBUG and print STDERR "opening $outfile for writing\n";
    if (! open(OUTFILE, ">$outfile")) {
        warn "Can't open $outfile for writing, skipping $filename";
	next Argument;
    }
    $state = 0;
    $arg = '';
    while (<CURRENT>) {                                                         
	if ($state == 0) {
	    if ( /^(\w+_SOURCES\s*=\s*)(.*)/s ) {
		print OUTFILE $1;
		$arg = $2;
		# chomp $arg;
		if ( $arg =~ /\\$/ ) {
		    $state = 1;
		} else {
		    print OUTFILE process_arg( $arg );
		}
	    } else {
		print OUTFILE; # keep looking
	    }
	} elsif ($state == 1) { # looking for more lines
	    $arg .= $_;
	    if ( ! /\\$/ ) { # got the whole SOURCES line, substitute
		print OUTFILE process_arg($arg);
		$arg = '';
		$state = 0;
	    }
	} else {
	    die 'Internal error, quitting';
	}
    }
    print OUTFILE process_arg($arg) if $arg;
    close $outfile;
}