package LWP::Protocol;

require LWP::MemberMixin;
@ISA = qw(LWP::MemberMixin);
$VERSION = "5.816";

use strict;
use Carp ();
use HTTP::Status ();
use HTTP::Response;

my %ImplementedBy = (); # scheme => classname



sub new
{
    my($class, $scheme, $ua) = @_;

    my $self = bless {
	scheme => $scheme,
	ua => $ua,

	# historical/redundant
        max_size => $ua->{max_size},
    }, $class;

    $self;
}


sub create
{
    my($scheme, $ua) = @_;
    my $impclass = LWP::Protocol::implementor($scheme) or
	Carp::croak("Protocol scheme '$scheme' is not supported");

    # hand-off to scheme specific implementation sub-class
    my $protocol = $impclass->new($scheme, $ua);

    return $protocol;
}


sub implementor
{
    my($scheme, $impclass) = @_;

    if ($impclass) {
	$ImplementedBy{$scheme} = $impclass;
    }
    my $ic = $ImplementedBy{$scheme};
    return $ic if $ic;

    return '' unless $scheme =~ /^([.+\-\w]+)$/;  # check valid URL schemes
    $scheme = $1; # untaint
    $scheme =~ s/[.+\-]/_/g;  # make it a legal module name

    # scheme not yet known, look for a 'use'd implementation
    $ic = "LWP::Protocol::$scheme";  # default location
    $ic = "LWP::Protocol::nntp" if $scheme eq 'news'; #XXX ugly hack
    no strict 'refs';
    # check we actually have one for the scheme:
    unless (@{"${ic}::ISA"}) {
	# try to autoload it
	eval "require $ic";
	if ($@) {
	    if ($@ =~ /Can't locate/) { #' #emacs get confused by '
		$ic = '';
	    }
	    else {
		die "$@\n";
	    }
	}
    }
    $ImplementedBy{$scheme} = $ic if $ic;
    $ic;
}


sub request
{
    my($self, $request, $proxy, $arg, $size, $timeout) = @_;
    Carp::croak('LWP::Protocol::request() needs to be overridden in subclasses');
}


# legacy
sub timeout    { shift->_elem('timeout',    @_); }
sub max_size   { shift->_elem('max_size',   @_); }


sub collect
{
    my ($self, $arg, $response, $collector) = @_;
    my $content;
    my($ua, $max_size) = @{$self}{qw(ua max_size)};

    eval {
        if (!defined($arg) || !$response->is_success) {