use v5.12.0;
use warnings;
package Email::MIME::Encode 1.954;
# ABSTRACT: a private helper for MIME header encoding

use Carp ();
use Encode ();
use Email::MIME::Header;
use MIME::Base64();
use Module::Runtime ();
use Scalar::Util;

our @CARP_NOT;

my %no_mime_headers = map { $_ => undef } qw(date message-id in-reply-to references downgraded-message-id downgraded-in-reply-to downgraded-references);

sub maybe_mime_encode_header {
  my ($header, $val, $charset) = @_;

  $header = lc $header;

  my $header_name_length = length($header) + length(": ");

  if (Scalar::Util::blessed($val) && $val->can("as_mime_string")) {
    return $val->as_mime_string({
      charset => $charset,
      header_name_length => $header_name_length,
    });
  }

  return _object_encode($val, $charset, $header_name_length, $Email::MIME::Header::header_to_class_map{$header})
    if exists $Email::MIME::Header::header_to_class_map{$header};

  my $min_wrap_length = 78 - $header_name_length + 1;

  return $val
    unless _needs_mime_encode($val) || $val =~ /[^\s]{$min_wrap_length,}/;

  return $val
    if exists $no_mime_headers{$header};

  return mime_encode($val, $charset, $header_name_length);
}

sub _needs_mime_encode {
  my ($val) = @_;
  return defined $val && $val =~ /(?:\P{ASCII}|=\?|[^\s]{79,}|^\s+|\s+$)/s;
}

sub _needs_mime_encode_addr {
  my ($val) = @_;
  return _needs_mime_encode($val) || ( defined $val && $val =~ /[:;,]/ );
}

sub _object_encode {
  my ($val, $charset, $header_name_length, $class) = @_;

  local @CARP_NOT = qw(Email::MIME Email::MIME::Header);

  {
    local $@;
    Carp::croak("Cannot load package '$class': $@") unless eval { Module::Runtime::require_module($class) };
  }

  Carp::croak("Class '$class' does not have method 'from_string'") unless $class->can('from_string');

  my $object = $class->from_string(ref $val eq 'ARRAY' ? @{$val} : $val);

  Carp::croak("Object from class '$class' does not have method 'as_mime_string'") unless $object->can('as_mime_string');

  return $object->as_mime_string({
    charset => $charset,
    header_name_length => $header_name_length,
  });
}

# XXX this is copied directly out of Courriel::Header
# eventually, this should be extracted out into something that could be shared
sub mime_encode {
  my ($text, $charset, $header_name_length) = @_;

  $header_name_length //= 0;
  $charset //= 'UTF-8';

  my $enc_obj = Encode::find_encoding($charset);

  my $head = '=?' . $enc_obj->mime_name() . '?B?';
  my $tail = '?=';

  my $mime_length = length($head) + length($tail);

  # This code is copied from Mail::Message::Field::Full in the Mail-Box
  # distro.
  my $real_length = int( ( 75 - $mime_length ) / 4 ) * 3;
  my $first_length = int( ( 75 - $header_name_length - $mime_length ) / 4 ) * 3;

  my @result;
  my $chunk = q{};
  my $first_processed = 0;
  while ( length( my $chr = substr( $text, 0, 1, '' ) ) ) {
    my $chr = $enc_obj->encode( $chr, 0 );

    if ( length($chunk) + length($chr) > ( $first_processed ? $real_length : $first_length ) ) {
      if ( length($chunk) > 0 ) {
        push @result, $head . MIME::Base64::encode_base64( $chunk, q{} ) . $tail;
        $chunk = q{};
      }
      $first_processed = 1
        unless $first_processed;
    }

    $chunk .= $chr;
  }

  push @result, $head . MIME::Base64::encode_base64( $chunk, q{} ) . $tail
    if length $chunk;

  return join q{ }, @result;
}

sub maybe_mime_decode_header {
  my ($header, $val) = @_;

  $header = lc $header;

  return _object_decode($val, $Email::MIME::Header::header_to_class_map{$header})
    if exists $Email::MIME::Header::header_to_class_map{$header};

  return $val
    if exists $no_mime_headers{$header};

  return $val
    unless $val =~ /=\?/;

  return mime_decode($val);
}

sub _object_decode {
  my ($string, $class) = @_;

  local @CARP_NOT = qw(Email::MIME Email::MIME::Header);

  {
    local $@;
    Carp::croak("Cannot load package '$class': $@") unless eval { Module::Runtime::require_module($class) };
  }

  Carp::croak("Class '$class' does not have method 'from_mime_string'") unless $class->can('from_mime_string');

  my $object = $class->from_mime_string($string);

  Carp::croak("Object from class '$class' does not have method 'as_string'") unless $object->can('as_string');

  return $object->as_string();
}

sub mime_decode {
  my ($text) = @_;
  return undef unless defined $text;

  # The eval is to cope with unknown encodings, like Latin-62, or other
  # nonsense that gets put in there by spammers and weirdos
  # -- rjbs, 2014-12-04
  local $@;
  my $result = eval { Encode::decode("MIME-Header", $text) };
  return $result // $text;
}

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

Email::MIME::Encode - a private helper for MIME header encoding

=head1 VERSION

version 1.954

=head1 PERL VERSION

This library should run on perls released even a long time ago.  It should
work on any version of perl released in the last five years.

Although it may work on older versions of perl, no guarantee is made that the
minimum required version will not be increased.  The version may be increased
for any reason, and there is no promise that patches will be accepted to
lower the minimum required perl.

=head1 AUTHORS

=over 4

=item *

Ricardo SIGNES <cpan@semiotic.systems>

=item *

Casey West <casey@geeknest.com>

=item *

Simon Cozens <simon@cpan.org>

=back

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2004 by Simon Cozens and Casey West.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut