#!/usr/bin/perl

use strict;
use warnings;
use File::Spec::Functions;

sub main(@) {
    foreach my $node (@_) {
	if (!process_node($node)) {
	    return 1;
	}
    }
    return 0;
}

sub process_node($) {
    my $node = shift();
    if (-f $node) {
	return process_file($node);
    } elsif (-d $node) {
	return process_dir($node);
    }
    return 0;
}

sub process_dir($) {
    my $dir = shift();
    if (opendir(DIR, $dir)) {
	if (my @nodes = readdir(DIR)) {
	    foreach my $node (no_upwards(@nodes)) {
		if (!process_node(catfile($dir, $node))) {
		    return 1;
		}
	    }
	} else {
	    print STDERR "$dir: could not read directory ($!)\n";
	    return 1;
	}
	closedir(DIR);
    } else {
	print STDERR "$dir: could not open directory ($!)\n";
	return 1;
    }
    return 0;
}

sub process_file($) {
    my $file = shift();
    if (open(FILE, $file)) {
	binmode(FILE);
	my $buffer;
	if (read(FILE, $buffer, 8)) {
	    my @fields = unpack('NN', $buffer);
	    if ($fields[0] == 0xCAFEBABE) {
		my $minor = ($fields[1] & 0xFF00) >> 16;
		my $major = $fields[1] & 0x00FF;
		my $version = '';
		if ($major == 45) {
		    if ($minor <= 3) {
			$version = '1.0.2';
		    } else {
			$version = '1.1.8';
		    }
		} elsif ($major == 46) {
		    $version = '1.2.2';
		} elsif ($major == 47) {
		    $version = '1.3.1';
		} elsif ($major == 48) {
		    $version = '1.4.2';
		} elsif ($major == 49) {
		    $version = '5.0';
		} elsif ($major == 50) {
		    $version = '6.0';
		} elsif ($major == 51) {
		    $version = '7.0';
		}
		print "$file: Java " . $version . " [" . $minor . "/" . $major . "]\n";
	    } else {
		print "$file: not a java class file\n";
	    }
	} else {
	    print STDERR "$file: could not read file ($!)\n";
	    return 1;
	}
	close(FILE);
    } else {
	print STDERR "$file: could not open file ($!)\n";
	return 1;
    }
    return 0;
}

exit main(@ARGV);