#!/usr/bin/perl -w

use strict;
use HTTP::Proxy qw/:log/;
use HTTP::Headers ;
use HTTP::Proxy::HeaderFilter;

# Variable init
my $host = undef;
my $port = 80;
my $log_file = "/tmp/proxy.log";
my $localhost = "proxy_host";  # the host where proxy is running
my $remotehost = "forwarded_host";
my $agent_timeout = 10;

sub search_credentials {
    my($iv_user,$iv_group) = @_;
    my($ht_user,$ht_passwd);
    # do some userid mapping funk
    # test example
    $ht_user   = 'username';
    $ht_passwd = 'password';
    return ($ht_user,$ht_passwd);
}

open(LOG,">>", $log_file);

my $proxy = HTTP::Proxy->new;
$proxy->port($port);
$proxy->host($host);
$proxy->logfh(*LOG);
#$proxy->logmask(STATUS | PROCESS );  # Normal logging
$proxy->logmask(STATUS | PROCESS | HEADERS | FILTER); # Debug logging

my $filter = HTTP::Proxy::HeaderFilter->new(
            sub {
                my ( $self, $headers, $message ) = @_;
                my $get_uri = $message->$headers->uri();
                print "Unaltered URI: $get_uri\n";

                my $iv_user = $message->$headers->header('iv-user');
                my $iv_group = $message->$headers->header('iv-group');
                my($ht_user,$ht_passwd) = search_credentials($iv_user,$iv_group);

                $message->$headers->authorization_basic($ht_user,$ht_passwd);

                $get_uri =~ s/$localhost/$remotehost/ if $get_uri =~ m/$localhost/ ;
                $get_uri =~ s?^/?http://$remotehost/? if $get_uri =~ m%^/% ;
                print "Altered URI: $get_uri\n";
                $message->$headers->uri($get_uri);
            }
);

$proxy->push_filter(request => $filter);

# this is the mainloop
$proxy->start;