#!/usr/bin/perl -w
#
# $Id$
#
# A script which inspects a hierarchy of classes and generates lists of
# classes that match specified criterion. The criterion are that a class
# or one if its parent classes extend a certain class or implement a
# certain interface.

use strict;
use Getopt::Long;

my $usage = "Usage: $0 [--verbose] [--prefix prefix] [--prune regexp]xN" .
    "[--implements interface]xN [--extends class --extends]xN jar_file ...\n";

# get our options
my $debug;
my $verbose;
my $prefix = "";
my @tifaces = ();
my @tclasses = ();
my @prunes = ();
GetOptions("debug" => \$debug,
           "verbose" => \$verbose,
           "prefix=s" => \$prefix,
           "prune=s" => \@prunes,
           "implements=s" => \@tifaces,
           "extends=s" => \@tclasses);

# create a classpath with all supplied jar files
my $classpath = join(":", @ARGV);

# enumerate all of the java classes in the supplied jar files
my %orig = ();
my @classes = ();
my $jar;
foreach $jar (@ARGV) {
    if (!open(JAR, "jar tvf $jar|")) {
        warn "Can't list contents of '$jar': $!\n";
        next;
    }

    while (<JAR>) {
        if (/\.class$/) {
            chomp;
            $_ =~ s:.* ([^ ]+\.class)$:$1:;
            $_ =~ s:\.class$::g;
            $_ =~ s:/:.:g;

            # keerist. for some reason javap insists that named inner
            # classes be referenced as Parent.Inner but anonymous inner
            # classes be referenced as Parent$Inner, but fucking DashO
            # wants them all as Parent$Inner, so we keep a mapping which
            # we use to report the $ version when generating our output
            my $orig = $_;
            if ($_ =~ s:\$:.:g) {
                $orig{$_} = $orig;
            }

            # make sure it matches our prefix
            next unless ($_ =~ /^$prefix/);

            # make sure it doesn't match any prunes
            my $matched = 0;
            my $prune;
            foreach $prune (@prunes) {
                if ($_ =~ /$prune/) {
                    $matched = 1;
                    last;
                }
            }
            next if ($matched != 0);

            print STDERR "Including $_\n" if $verbose;
            push @classes, $_;
        }
    }
    close(JAR);
}

# run javap on all of these classes and calculate the inheritence and
# interface implementation metadata
my %ptable = ();
my %itable = ();
my @gclasses = @classes;
while (@gclasses) {
    # roll off twenty classes or so at a time
    my $ccount = @gclasses;
    my @cargs = splice(@gclasses, 0, min($ccount, 100));
    my $carg = "'" . join("' '", @cargs) . "'";

    # print STDERR "javap -classpath $classpath $carg\n";

    if (!open(JAVAP, "javap -classpath $classpath $carg|")) {
        warn "Can't inspect $carg: $!\n";
        next;
    }

    # look for a line that identifies a class or interface
    while (<JAVAP>) {
        chomp;
        my $goods = $_;
        my $class;
        next unless ($class = match_class($goods));

        # strip off the close brace
        $goods =~ s:\s*{\s*$::g;

        # interfaces are now at the end of the line
        my @ifaces;
        if ($goods =~ s: implements (.*)$::g) {
            my $idefs = clean_class($1);
            @ifaces = split(/,/, $idefs);
        }

        if (@ifaces) {
            $itable{$class} = \@ifaces;
            print STDERR "-> $class I[" . join(":", @ifaces) . "]\n"
                if ($debug);
        }

        # now the parent class or parent interfaces are at the end
        my @parents;
        if ($goods =~ s: extends (.*)$::g) {
            my $pdefs = clean_class($1);
            @parents = split(/,/, $pdefs);
        }

        if (@parents) {
            $ptable{$class} = \@parents;
            print STDERR "-> $class E[" . join(":", @parents) . "]\n"
                if ($debug);
        }
    }
    close(JAVAP);
}

my %matches = ();
# now blow through the classes looking for matches
my $class;
foreach $class (@classes) {
    # check for an interface match
    my $tiface;
    foreach $tiface (@tifaces) {
        print STDERR "Checking $class implements $tiface\n" if ($debug);
        if (implements($class, $tiface)) {
            print STDERR "$class implements $tiface\n" if ($verbose);
            $matches{$class} = 1;
        }
    }
    # check for a class match
    my $tclass;
    foreach $tclass (@tclasses) {
        print STDERR "Checking $class extends $tclass\n" if ($debug);
        if (extends($class, $tclass)) {
            print STDERR "$class extends $tclass\n" if ($verbose);
            $matches{$class} = 1;
        }
    }
}

# print out the results
foreach $class (sort keys %matches) {
    print defined $orig{$class} ?  "$orig{$class}\n" :  "$class\n";
}
# print STDERR join("\n", ) . "\n";

# Guess what this does.
sub min {
    my ($a, $b) = @_;
    return ($a < $b) ? $a : $b;
}

# Matches a class declaration on the supplied line
sub match_class {
    my ($line) = @_;
    # print STDERR "Matching $line\n";
    if ($line !~ m:[a-z ]*(class|interface) ([A-Za-z0-9.\$]+):) {
        return undef;
    }
    # print STDERR "Matched $2\n";
    my $class = clean_class($2);
    $class =~ s: ::g;
    return $class;
}

# Cleans up class n ames as reported by javap
sub clean_class {
    my ($class) = @_;
    $class =~ s:\s+$::g;
    $class =~ s:\. :\$:g;
    $class =~ s: ::g;
    $class =~ s:\$:.:g;
    return $class;
}

# Reports whether or not the specified class is an instanceof the
# specified target interface.
sub implements {
    my ($class, $target) = @_;

    # scan up this classes parent hierarchy looking to see if it or any
    # parent class implements the specified interface (or a derived
    # interface)
    my $crecord = $ptable{$class};
    if (defined $crecord) {
        # check the interfaces implemented by this class
        my $irecord = $itable{$class};
        if (defined $irecord) {
            my $iface;
            foreach $iface (@{$irecord}) {
                return 1 if (extends($iface, $target));
            }
        }

        # check our parents
        my $pclass;
        foreach $pclass (@{$crecord}) {
            return 1 if (implements($pclass, $target));
        }
    }

    return 0;
}

# Reports whether or not the specified class is an instanceof the
# specified target class.
sub extends {
    my ($class, $target) = @_;

    # if we are the class, we're good
    return 1 if ($class eq $target);

    # look to see if any of our parent classes extend the target class
    # (recursing as necessary up the hierarchy)
    my $crecord = $ptable{$class};
    if (defined $crecord) {
        my $pclass;
        foreach $pclass (@{$crecord}) {
            return 1 if (extends($pclass, $target));
        }
    }

    return 0;
}