#!@PERL@ -s -w
#
# javaDependencies Copyright (C) 1999 Jochen Hoenicke.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; see the file COPYING.  If not, write to
# the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
#
# $Id$

# This scripts create Makefile dependencies out of class files.  It
# simply scans the constant pool of the class files, finding all
# references to other classes and adding a dependency to that class.
#
# It doesn't do a perfect job, since it can't handle dependencies to 
# constant values in different classes:  The compiler inlines the 
# constant and thus doesn't include a reference to the class.
#
# Usage:  
#  javaDependencies.pl -classpath <cp> [-dependdir <depdir>] <classfile>
# 
#  cp:     colon separated paths to the java files we should depend on.
#  depdir: if set, use this path as path to the java files when printing
#          dependencies, not the path where the java files were found.
#          useful, if you want to make use of VPATH settings in Makefile.
#  class:  The class file (not an inner class) for which the dependencies
#          should be generated.  We will also look for inner and anon 
#          classes.

my $buff;

sub readInBuff ($) {
    my $count = $_[0];
    my $offset = 0;
    while ($count > 0) {
        my $result = read FILE, $buff, $count, $offset or 0;
	$offset += $result;
	$count -= $result;
    }
    $offset;
}

sub readUTF () {
    readInBuff 2 or die "Can't read UTF8 length";
    my $ulength = unpack("n", $buff) & 0xffff;
    return "" if $ulength == 0;
    readInBuff $ulength or die "Can't read UTF8 string $ulength";
    unpack("a$ulength", $buff);
}

$clazz = pop;
$clazz =~ /(.*)\.class/ or die "not a class file";
$base = $1;
my ($filename, %done);
%done=();
for $filename ($clazz, glob("$base\\\$*.class")) {
    open FILE, $filename;
    binmode FILE;

    readInBuff 8 or die "Can't read header";
    my ($magic, $minor, $major) = unpack("Nnn", $buff);

    die "Wrong magic $magic" if $magic != 0xcafebabe;
    die "Wrong minor $minor" if $minor > 3;
    die "Wrong minor $major" if $major != 45;
    
    readInBuff 2 or die "Can't read cpool length";
    
    
    my ($length) = unpack("n", $buff) & 0xffff;

    my $number;
    my @strings = ();
    my @clazzes;
    for ($number = 1; $number < $length; $number++) {
	
	readInBuff 1 or die "Can't read constant tag";
	my ($tag) = unpack("C", $buff);

	#print STDERR "$number/$length: $tag";
      tags:
	for ($tag) {
	    /^1$/ && do { 
		# UTF 8
		$strings[$number] = &readUTF();
		#print STDERR ": $strings[$number]";
		last tags;
	    }; 
	    
	    /^(3|4|9|10|11|12)$/ && do {
		# INTEGER, FLOAT, FIELDREF, METHODREF, IFACEREF, NAMEANDTYPE
		readInBuff 4;
		last tags;
	    }; 
	    
	    /^(5|6)$/ && do {
		# LONG, DOUBLE
		readInBuff 8;
		$number++;
		last tags;
	    };
	    
	    /^7$/ && do {
		# CLASS
		readInBuff 2;
		push @clazzes, (unpack("n", $buff) & 0xffff);
		last tags;
	    }; 
	    
	    /^8$/ && do {
		# STRING
		readInBuff 2;
		last tags;
	    };
	    die "Unknown tag: $tag, $number/$length, $filename";
	}
	#print STDERR "\n";
    }
    

    my @deplist = ();
  clazz:
    for $c (@clazzes) {
	$clzz = $strings[$c];
	next if $clzz =~ /^\[/;
	next if defined $done{"$clzz"};
	$done{$clzz} = 1;

	for $p (split ':', $classpath) {
	    if (-e "$p/$clzz.java") {
		push @deplist, (defined $dependdir
				? "$dependdir/$clzz.java"
				: "$p/$clzz.java");
		next clazz;
	    }
	}
    }
    if (@deplist) {
	print "# Dependencies of $filename\n";
	print "$clazz: " . join (" ", @deplist) . "\n";
    }
}