package LWP::Debug;

require Exporter;
@ISA = qw(Exporter);
@EXPORT_OK = qw(level trace debug conns);

use Carp ();

my @levels = qw(trace debug conns);
%current_level = ();


sub import
{
    my $pack = shift;
    my $callpkg = caller(0);
    my @symbols = ();
    my @levels = ();
    for (@_) {
	if (/^[-+]/) {
	    push(@levels, $_);
	}
	else {
	    push(@symbols, $_);
	}
    }
    Exporter::export($pack, $callpkg, @symbols);
    level(@levels);
}


sub level
{
    for (@_) {
	if ($_ eq '+') {              # all on
	    # switch on all levels
	    %current_level = map { $_ => 1 } @levels;
	}
	elsif ($_ eq '-') {           # all off
	    %current_level = ();
	}
	elsif (/^([-+])(\w+)$/) {
	    $current_level{$2} = $1 eq '+';
	}
	else {
	    Carp::croak("Illegal level format $_");
	}
    }
}


sub trace  { _log(@_) if $current_level{'trace'}; }
sub debug  { _log(@_) if $current_level{'debug'}; }
sub conns  { _log(@_) if $current_level{'conns'}; }


sub _log
{
    my $msg = shift;
    $msg .= "\n" unless $msg =~ /\n$/;  # ensure trailing "\n"

    my($package,$filename,$line,$sub) = caller(2);
    print STDERR "$sub: $msg";
}

1;


__END__

=head1 NAME

LWP::Debug - debug routines for the libwww-perl library

=head1 SYNOPSIS

 use LWP::Debug qw(+ -conns);

 # Used internally in the library
 LWP::Debug::trace('send()');
 LWP::Debug::debug('url ok');
 LWP::Debug::conns("read $n bytes: $data");

=head1 DESCRIPTION

LWP::Debug provides tracing facilities. The trace(), debug() and
conns() function are called within the library and they log
information at increasing levels of detail. Which level of detail is
actually printed is controlled with the C<level()> function.

The following functions are available:

=over 4

=item level(...)

The C<level()> function controls the level of detail being
logged. Passing '+' or '-' indicates full and no logging
respectively. Individual levels can switched on and of by passing the
name of the level with a '+' or '-' prepended.  The levels are: