package WWW::RobotRules::AnyDBM_File;

require  WWW::RobotRules;
@ISA = qw(WWW::RobotRules);
$VERSION = "6.00";

use Carp ();
use AnyDBM_File;
use Fcntl;
use strict;

=head1 NAME

WWW::RobotRules::AnyDBM_File - Persistent RobotRules

=head1 SYNOPSIS

 require WWW::RobotRules::AnyDBM_File;
 require LWP::RobotUA;

 # Create a robot useragent that uses a diskcaching RobotRules
 my $rules = WWW::RobotRules::AnyDBM_File->new( 'my-robot/1.0', 'cachefile' );
 my $ua = WWW::RobotUA->new( 'my-robot/1.0', 'me@foo.com', $rules );

 # Then just use $ua as usual
 $res = $ua->request($req);

=head1 DESCRIPTION

This is a subclass of I<WWW::RobotRules> that uses the AnyDBM_File
package to implement persistent diskcaching of F<robots.txt> and host
visit information.

The constructor (the new() method) takes an extra argument specifying
the name of the DBM file to use.  If the DBM file already exists, then
you can specify undef as agent name as the name can be obtained from
the DBM database.

=cut

sub new 
{ 
  my ($class, $ua, $file) = @_;
  Carp::croak('WWW::RobotRules::AnyDBM_File filename required') unless $file;

  my $self = bless { }, $class;
  $self->{'filename'} = $file;
  tie %{$self->{'dbm'}}, 'AnyDBM_File', $file, O_CREAT|O_RDWR, 0640
    or Carp::croak("Can't open $file: $!");
  
  if ($ua) {
      $self->agent($ua);
  }
  else {
      # Try to obtain name from DBM file
      $ua = $self->{'dbm'}{"|ua-name|"};
      Carp::croak("No agent name specified") unless $ua;
  }

  $self;
}

sub agent {
    my($self, $newname) = @_;
    my $old = $self->{'dbm'}{"|ua-name|"};
    if (defined $newname) {
	$newname =~ s!/?\s*\d+.\d+\s*$!!;  # loose version
	unless ($old && $old eq $newname) {
	# Old info is now stale.
	    my $file = $self->{'filename'};
	    untie %{$self->{'dbm'}};
	    tie %{$self->{'dbm'}}, 'AnyDBM_File', $file, O_TRUNC|O_RDWR, 0640;
	    %{$self->{'dbm'}} = ();
	    $self->{'dbm'}{"|ua-name|"} = $newname;
	}
    }
    $old;
}

sub no_visits {
    my ($self, $netloc) = @_;
    my $t = $self->{'dbm'}{"$netloc|vis"};
    return 0 unless $t;
    (split(/;\s*/, $t))[0];
}

sub last_visit {
    my ($self, $netloc) = @_;
    my $t = $self->{'dbm'}{"$netloc|vis"};
    return undef unless $t;
    (split(/;\s*/, $t))[1];
}

sub fresh_until {
    my ($self, $netloc, $fresh) = @_;
    my $old = $self->{'dbm'}{"$netloc|exp"};
    if ($old) {
	$old =~ s/;.*//;  # remove cleartext
    }
    if (defined $fresh) {
	$fresh .= "; " . localtime($fresh);
	$self->{'dbm'}{"$netloc|exp"} = $fresh;
    }
    $old;
}

sub visit {
    my($self, $netloc, $time) = @_;
    $time ||= time;

    my $count = 0;
    my $old = $self->{'dbm'}{"$netloc|vis"};
    if ($old) {
	my $last;
	($count,$last) = split(/;\s*/, $old);
	$time = $last if $last > $time;
    }
    $count++;
    $self->{'dbm'}{"$netloc|vis"} = "$count; $time; " . localtime($time);
}

sub push_rules {
    my($self, $netloc, @rules) = @_;
    my $cnt = 1;
    $cnt++ while $self->{'dbm'}{"$netloc|r$cnt"};

    foreach (@rules) {
	$self->{'dbm'}{"$netloc|r$cnt"} = $_;
	$cnt++;
    }
}

sub clear_rules {
    my($self, $netloc) = @_;
    my $cnt = 1;
    while ($self->{'dbm'}{"$netloc|r$cnt"}) {
	delete $self->{'dbm'}{"$netloc|r$cnt"};
	$cnt++;
    }
}

sub rules {
    my($self, $netloc) = @_;
    my @rules = ();
    my $cnt = 1;
    while (1) {
	my $rule = $self->{'dbm'}{"$netloc|r$cnt"};
	last unless $rule;
	push(@rules, $rule);
	$cnt++;
    }
    @rules;
}

sub dump
{
}

1;

=head1 SEE ALSO

L<WWW::RobotRules>, L<LWP::RobotUA>

=head1 AUTHORS

Hakan Ardo E<lt>hakan@munin.ub2.lu.se>, Gisle Aas E<lt>aas@sn.no>

=cut