#!/usr/bin/perl

use warnings;
use strict;

use HTTP::Proxy qw(:log);
use HTTP::Proxy::HeaderFilter::simple;
use HTTP::Proxy::BodyFilter::save;

use Getopt::Long;
use Pod::Usage;
use LWP::UserAgent;
use URI;

my %mirror = ();
my $mirror_root;

my $verbose = 1;
my $port_to_listen;
my $interface_address_or_hostname;

Getopt::Long::Configure ('bundling');
GetOptions(
    'verbose|v+'   => \$verbose,
    'port|p=i'     => \$port_to_listen,
    'I=s'          => \$interface_address_or_hostname,
    'local|l=s'    => \$mirror{'local'},
    'external|e=s' => \$mirror{'external'},
    'root|r=s'     => \$mirror_root,
    'help|h|?'     => pod2usage(1),
) or pod2usage(1);

pod2usage(1) 
    unless defined $mirror{'local'} and $mirror{'external'} and $mirror_root;

my $proxy = HTTP::Proxy->new(
    port => $port_to_listen || 8080,
    host => $interface_address_or_hostname || 'localhost.localdomain',
    logmask => $verbose > 2 ? ALL : $verbose > 1 ? STATUS : FILTERS,

    engine => 'ScoreBoard', #Forking engine.
);

my $ua = LWP::UserAgent->new();

$proxy->push_filter(
    request => HTTP::Proxy::HeaderFilter::simple->new(
        sub {
            my ( $self, $headers, $message ) = @_;

            return "Not a request"
              unless $message->isa('HTTP::Request');

            my $path = $message->uri->path;
            my $uri  = URI->new( $mirror{local} . $path );

            my $selected = $ua->head($uri)->is_success ? 'local' : 'external';

            $self->proxy->log( HTTP::Proxy::FILTERS,
                "\u$selected mirror for $path" );

            $message->uri( $mirror{$selected} . $path );

        }
    ),
    response => HTTP::Proxy::BodyFilter::save->new(
        prefix   => $mirror_root,
        template => '%d/%f',
        multiple => undef,
    ),
);

$proxy->start;

__END__
=head1 NAME

automirror.pl - A program to mirror files as you download them.

=head1 SYNOPSIS

automirror.pl [options]

 Options:
   -v, --verbose    Increase verbosity level.
   -p, --port       Port to listen for connections.
   -I, --iface      Listen only in this interface address or hostname
   -l, --local      Local mirror address.
   -e, --external   External mirror address.
   -r, --root       Root of the mirror.

=head1 OPTIONS

=over 8

=item B<--verbose>

Increase verbosity level.

    -v      - File and mirror selection information.
    -vv     - Request and response information.
    -vvv    - ALL verbosity avaliable.

B<Defaults> to -v

=item B<--port>

Port to listen for connections.

B<Defauls> to 8080

=item B<--iface>

Listen only in this interface address or hostname.
(eg. 192.168.0.1, localhost or centos.intranet.poormen.com)

B<Defaults> to localhost.localdomain

=back

=head1 DESCRIPTION

B<This program> will act as a transparent proxy for a http server, 
mirroring the files to a especified location as you download them.
This is useful for mirroring package repositories, but only the files
you've already downloaded.
Please note that you still need a working local http server configured
to serve the files stored in the location you especified on --root
and a external mirror from where to download the files you don`t have
already.
Of course, this program and the local mirror must run on the same machine,
or share a filesytem somehow. NFS or SMB shares, for example.

=cut