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package RT::Interface::Email;

use strict;
use warnings;
use 5.010;

use Email::Address;
use MIME::Entity;
use RT::EmailParser;
use File::Temp;
use Mail::Mailer ();
use Text::ParseWords qw/shellwords/;
use RT::Util 'safe_run_child';
use File::Spec;

BEGIN {
    use base 'Exporter';
    use vars qw ( @EXPORT_OK);

    # your exported package globals go here,
    # as well as any optionally exported functions
    @EXPORT_OK = qw(
        &CreateUser
        &CheckForLoops
        &CheckForSuspiciousSender
        &CheckForAutoGenerated
        &CheckForBounce
        &MailError
        &ParseCcAddressesFromHead
        &ParseSenderAddressFromHead
        &ParseErrorsToAddressFromHead
        &ParseAddressFromHeader
        &Gateway);

}

=head1 NAME

  RT::Interface::Email - helper functions for parsing email sent to RT

=head1 SYNOPSIS

  use lib "!!RT_LIB_PATH!!";
  use lib "!!RT_ETC_PATH!!";

  use RT::Interface::Email  qw(Gateway CreateUser);

=head1 DESCRIPTION




=head1 METHODS

=head2 CheckForLoops HEAD

Takes a HEAD object of L<MIME::Head> class and returns true if the
message's been sent by this RT instance. Uses "X-RT-Loop-Prevention"
field of the head for test.

=cut

sub CheckForLoops {
    my $head = shift;

    # If this instance of RT sent it our, we don't want to take it in
    my $RTLoop = Encode::decode( "UTF-8", $head->get("X-RT-Loop-Prevention") || "" );
    chomp ($RTLoop); # remove that newline
    if ( $RTLoop eq RT->Config->Get('rtname') ) {
        return 1;
    }

    # TODO: We might not trap the case where RT instance A sends a mail
    # to RT instance B which sends a mail to ...
    return undef;
}

=head2 CheckForSuspiciousSender HEAD

Takes a HEAD object of L<MIME::Head> class and returns true if sender
is suspicious. Suspicious means mailer daemon.

See also L</ParseSenderAddressFromHead>.

=cut

sub CheckForSuspiciousSender {
    my $head = shift;

    #if it's from a postmaster or mailer daemon, it's likely a bounce.

    #TODO: better algorithms needed here - there is no standards for
    #bounces, so it's very difficult to separate them from anything
    #else.  At the other hand, the Return-To address is only ment to be
    #used as an error channel, we might want to put up a separate
    #Return-To address which is treated differently.

    #TODO: search through the whole email and find the right Ticket ID.

    my ( $From, $junk ) = ParseSenderAddressFromHead($head);

    # If unparseable (non-ASCII), $From can come back undef
    return undef if not defined $From;

    if (   ( $From =~ /^mailer-daemon\@/i )
        or ( $From =~ /^postmaster\@/i )
        or ( $From eq "" ))
    {
        return (1);

    }

    return undef;
}

=head2 CheckForAutoGenerated HEAD

Takes a HEAD object of L<MIME::Head> class and returns true if message is
autogenerated. Checks C<Precedence>, C<Auto-Submitted>, and
C<X-FC-Machinegenerated> fields of the head in tests.

=cut

sub CheckForAutoGenerated {
    my $head = shift;

    if (grep { /^(bulk|junk)/i } $head->get_all("Precedence")) {
        return (1);
    }

    # Per RFC3834, any Auto-Submitted header which is not "no" means
    # it is auto-generated.
    my $AutoSubmitted = $head->get("Auto-Submitted") || "";
    if ( length $AutoSubmitted and $AutoSubmitted ne "no" ) {
        return (1);
    }

    # First Class mailer uses this as a clue.
    my $FCJunk = $head->get("X-FC-Machinegenerated") || "";
    if ( $FCJunk =~ /^true/i ) {
        return (1);
    }

    return (0);
}


sub CheckForBounce {
    my $head = shift;

    my $ReturnPath = $head->get("Return-path") || "";
    return ( $ReturnPath =~ /<>/ );
}


=head2 MailError PARAM HASH

Sends an error message. Takes a param hash:

=over 4

=item From - sender's address, by default is 'CorrespondAddress';

=item To - recipient, by default is 'OwnerEmail';

=item Bcc - optional Bcc recipients;

=item Subject - subject of the message, default is 'There has been an error';

=item Explanation - main content of the error, default value is 'Unexplained error';

=item MIMEObj - optional MIME entity that's attached to the error mail, as well we
add 'In-Reply-To' field to the error that points to this message.

=item Attach - optional text that attached to the error as 'message/rfc822' part.

=item LogLevel - log level under which we should write the subject and
explanation message into the log, by default we log it as critical.

=back

=cut

sub MailError {
    my %args = (
        To          => RT->Config->Get('OwnerEmail'),
        Bcc         => undef,
        From        => RT->Config->Get('CorrespondAddress'),
        Subject     => 'There has been an error',
        Explanation => 'Unexplained error',
        MIMEObj     => undef,
        Attach      => undef,
        LogLevel    => 'crit',
        @_
    );

    $RT::Logger->log(
        level   => $args{'LogLevel'},
        message => "$args{Subject}: $args{'Explanation'}",
    ) if $args{'LogLevel'};

    # the colons are necessary to make ->build include non-standard headers
    my %entity_args = (
        Type                    => "multipart/mixed",
        From                    => Encode::encode( "UTF-8", $args{'From'} ),
        Bcc                     => Encode::encode( "UTF-8", $args{'Bcc'} ),
        To                      => Encode::encode( "UTF-8", $args{'To'} ),
        Subject                 => EncodeToMIME( String => $args{'Subject'} ),
        'X-RT-Loop-Prevention:' => Encode::encode( "UTF-8", RT->Config->Get('rtname') ),
    );

    # only set precedence if the sysadmin wants us to
    if (defined(RT->Config->Get('DefaultErrorMailPrecedence'))) {
        $entity_args{'Precedence:'} =
            Encode::encode( "UTF-8", RT->Config->Get('DefaultErrorMailPrecedence') );
    }

    my $entity = MIME::Entity->build(%entity_args);
    SetInReplyTo( Message => $entity, InReplyTo => $args{'MIMEObj'} );

    $entity->attach(
        Type    => "text/plain",
        Charset => "UTF-8",
        Data    => Encode::encode( "UTF-8", $args{'Explanation'} . "\n" ),
    );

    if ( $args{'MIMEObj'} ) {
        $args{'MIMEObj'}->sync_headers;
        $entity->add_part( $args{'MIMEObj'} );
    }

    if ( $args{'Attach'} ) {
        $entity->attach( Data => Encode::encode( "UTF-8", $args{'Attach'} ), Type => 'message/rfc822' );

    }

    SendEmail( Entity => $entity, Bounce => 1 );
}


=head2 SendEmail Entity => undef, [ Bounce => 0, Ticket => undef, Transaction => undef ]

Sends an email (passed as a L<MIME::Entity> object C<ENTITY>) using
RT's outgoing mail configuration. If C<BOUNCE> is passed, and is a
true value, the message will be marked as an autogenerated error, if
possible. Sets Date field of the head to now if it's not set.

If the C<X-RT-Squelch> header is set to any true value, the mail will
not be sent. One use is to let extensions easily cancel outgoing mail.

Ticket and Transaction arguments are optional. If Transaction is
specified and Ticket is not then ticket of the transaction is
used, but only if the transaction belongs to a ticket.

Returns 1 on success, 0 on error or -1 if message has no recipients
and hasn't been sent.

=head3 Signing and Encrypting

This function as well signs and/or encrypts the message according to
headers of a transaction's attachment or properties of a ticket's queue.
To get full access to the configuration Ticket and/or Transaction
arguments must be provided, but you can force behaviour using Sign
and/or Encrypt arguments.

The following precedence of arguments are used to figure out if
the message should be encrypted and/or signed:

* if Sign or Encrypt argument is defined then its value is used

* else if Transaction's first attachment has X-RT-Sign or X-RT-Encrypt
header field then it's value is used

* else properties of a queue of the Ticket are used.

=cut

sub WillSignEncrypt {
    my %args = @_;
    my $attachment = delete $args{Attachment};
    my $ticket     = delete $args{Ticket};

    if ( not RT->Config->Get('Crypt')->{'Enable'} ) {
        $args{Sign} = $args{Encrypt} = 0;
        return wantarray ? %args : 0;
    }

    for my $argument ( qw(Sign Encrypt) ) {
        next if defined $args{ $argument };

        if ( $attachment and defined $attachment->GetHeader("X-RT-$argument") ) {
            $args{$argument} = $attachment->GetHeader("X-RT-$argument");
        } elsif ( $ticket and $argument eq "Encrypt" ) {
            $args{Encrypt} = $ticket->QueueObj->Encrypt();
        } elsif ( $ticket and $argument eq "Sign" ) {
            # Note that $queue->Sign is UI-only, and that all
            # UI-generated messages explicitly set the X-RT-Crypt header
            # to 0 or 1; thus this path is only taken for messages
            # generated _not_ via the web UI.
            $args{Sign} = $ticket->QueueObj->SignAuto();
        }
    }

    return wantarray ? %args : ($args{Sign} || $args{Encrypt});
}

sub _OutgoingMailFrom {
    my $TicketObj = shift;

    my $MailFrom = RT->Config->Get('SetOutgoingMailFrom');
    my $OutgoingMailAddress = $MailFrom =~ /\@/ ? $MailFrom : undef;
    my $Overrides = RT->Config->Get('OverrideOutgoingMailFrom') || {};

    if ($TicketObj) {
        my $Queue = $TicketObj->QueueObj;
        my $QueueAddressOverride = $Overrides->{$Queue->id}
            || $Overrides->{$Queue->Name};

        if ($QueueAddressOverride) {
            $OutgoingMailAddress = $QueueAddressOverride;
        } else {
            $OutgoingMailAddress ||= $Queue->CorrespondAddress
                || RT->Config->Get('CorrespondAddress');
        }
    }
    elsif ($Overrides->{'Default'}) {
        $OutgoingMailAddress = $Overrides->{'Default'};
    }

    return $OutgoingMailAddress;
}

sub SendEmail {
    my (%args) = (
        Entity => undef,
        Bounce => 0,
        Ticket => undef,
        Transaction => undef,
        @_,
    );

    my $TicketObj = $args{'Ticket'};
    my $TransactionObj = $args{'Transaction'};

    unless ( $args{'Entity'} ) {
        $RT::Logger->crit( "Could not send mail without 'Entity' object" );
        return 0;
    }

    my $msgid = Encode::decode( "UTF-8", $args{'Entity'}->head->get('Message-ID') || '' );
    chomp $msgid;
    
    # If we don't have any recipients to send to, don't send a message;
    unless ( $args{'Entity'}->head->get('To')
        || $args{'Entity'}->head->get('Cc')
        || $args{'Entity'}->head->get('Bcc') )
    {
        $RT::Logger->info( $msgid . " No recipients found. Not sending." );
        return -1;
    }

    if ($args{'Entity'}->head->get('X-RT-Squelch')) {
        $RT::Logger->info( $msgid . " Squelch header found. Not sending." );
        return -1;
    }

    if (my $precedence = RT->Config->Get('DefaultMailPrecedence')
        and !$args{'Entity'}->head->get("Precedence")
    ) {
        if ($TicketObj) {
            my $Overrides = RT->Config->Get('OverrideMailPrecedence') || {};
            my $Queue = $TicketObj->QueueObj;

            $precedence = $Overrides->{$Queue->id}
                if exists $Overrides->{$Queue->id};
            $precedence = $Overrides->{$Queue->Name}
                if exists $Overrides->{$Queue->Name};
        }

        $args{'Entity'}->head->replace( 'Precedence', Encode::encode("UTF-8",$precedence) )
            if $precedence;
    }

    if ( $TransactionObj && !$TicketObj
        && $TransactionObj->ObjectType eq 'RT::Ticket' )
    {
        $TicketObj = $TransactionObj->Object;
    }

    my $head = $args{'Entity'}->head;
    unless ( $head->get('Date') ) {
        require RT::Date;
        my $date = RT::Date->new( RT->SystemUser );
        $date->SetToNow;
        $head->replace( 'Date', Encode::encode("UTF-8",$date->RFC2822( Timezone => 'server' ) ) );
    }
    unless ( $head->get('MIME-Version') ) {
        # We should never have to set the MIME-Version header
        $head->replace( 'MIME-Version', '1.0' );
    }
    unless ( $head->get('Content-Transfer-Encoding') ) {
        # fsck.com #5959: Since RT sends 8bit mail, we should say so.
        $head->replace( 'Content-Transfer-Encoding', '8bit' );
    }

    if ( RT->Config->Get('Crypt')->{'Enable'} ) {
        %args = WillSignEncrypt(
            %args,
            Attachment => $TransactionObj ? $TransactionObj->Attachments->First : undef,
            Ticket     => $TicketObj,
        );
        my $res = SignEncrypt( %args );
        return $res unless $res > 0;
    }

    my $mail_command = RT->Config->Get('MailCommand');

    # if it is a sub routine, we just return it;
    return $mail_command->($args{'Entity'}) if UNIVERSAL::isa( $mail_command, 'CODE' );

    if ( $mail_command eq 'sendmailpipe' ) {
        my $path = RT->Config->Get('SendmailPath');
        my @args = shellwords(RT->Config->Get('SendmailArguments'));
        push @args, "-t" unless grep {$_ eq "-t"} @args;

        # SetOutgoingMailFrom and bounces conflict, since they both want -f
        if ( $args{'Bounce'} ) {
            push @args, shellwords(RT->Config->Get('SendmailBounceArguments'));
        } elsif ( RT->Config->Get('SetOutgoingMailFrom') ) {
            my $OutgoingMailAddress = _OutgoingMailFrom($TicketObj);

            push @args, "-f", $OutgoingMailAddress
                if $OutgoingMailAddress;
        }

        # VERP
        if ( $TransactionObj and
             my $prefix = RT->Config->Get('VERPPrefix') and
             my $domain = RT->Config->Get('VERPDomain') )
        {
            my $from = $TransactionObj->CreatorObj->EmailAddress;
            $from =~ s/@/=/g;
            $from =~ s/\s//g;
            push @args, "-f", "$prefix$from\@$domain";
        }

        eval {
            # don't ignore CHLD signal to get proper exit code
            local $SIG{'CHLD'} = 'DEFAULT';

            # if something wrong with $mail->print we will get PIPE signal, handle it
            local $SIG{'PIPE'} = sub { die "program unexpectedly closed pipe" };

            require IPC::Open2;
            my ($mail, $stdout);
            my $pid = IPC::Open2::open2( $stdout, $mail, $path, @args )
                or die "couldn't execute program: $!";

            $args{'Entity'}->print($mail);
            close $mail or die "close pipe failed: $!";

            waitpid($pid, 0);
            if ($?) {
                # sendmail exit statuses mostly errors with data not software
                # TODO: status parsing: core dump, exit on signal or EX_*
                my $msg = "$msgid: `$path @args` exited with code ". ($?>>8);
                $msg = ", interrupted by signal ". ($?&127) if $?&127;
                $RT::Logger->error( $msg );
                die $msg;
            }
        };
        if ( $@ ) {
            $RT::Logger->crit( "$msgid: Could not send mail with command `$path @args`: " . $@ );
            if ( $TicketObj ) {
                _RecordSendEmailFailure( $TicketObj );
            }
            return 0;
        }
    } elsif ( $mail_command eq 'mbox' ) {
        my $now = RT::Date->new(RT->SystemUser);
        $now->SetToNow;

        state $logfile;
        unless ($logfile) {
            my $when = $now->ISO( Timezone => "server" );
            $when =~ s/\s+/-/g;
            $logfile = "$RT::VarPath/$when.mbox";
            $RT::Logger->info("Storing outgoing emails in $logfile");
        }

        my $fh;
        unless (open($fh, ">>", $logfile)) {
            $RT::Logger->crit( "Can't open mbox file $logfile: $!" );
            return 0;
        }
        my $content = $args{Entity}->stringify;
        $content =~ s/^(>*From )/>$1/mg;
        my $user = $ENV{USER} || getpwuid($<);
        print $fh "From $user\@localhost  ".localtime()."\n";
        print $fh $content, "\n";
        close $fh;
    } else {
        local ($ENV{'MAILADDRESS'}, $ENV{'PERL_MAILERS'});

        my @mailer_args = ($mail_command);
        if ( $mail_command eq 'sendmail' ) {
            $ENV{'PERL_MAILERS'} = RT->Config->Get('SendmailPath');
            push @mailer_args, grep {$_ ne "-t"}
                split(/\s+/, RT->Config->Get('SendmailArguments'));
        } elsif ( $mail_command eq 'testfile' ) {
            unless ($Mail::Mailer::testfile::config{outfile}) {
                $Mail::Mailer::testfile::config{outfile} = File::Temp->new;
                $RT::Logger->info("Storing outgoing emails in $Mail::Mailer::testfile::config{outfile}");
            }
        } else {
            push @mailer_args, RT->Config->Get('MailParams');
        }

        unless ( $args{'Entity'}->send( @mailer_args ) ) {
            $RT::Logger->crit( "$msgid: Could not send mail." );
            if ( $TicketObj ) {
                _RecordSendEmailFailure( $TicketObj );
            }
            return 0;
        }
    }
    return 1;
}

=head2 PrepareEmailUsingTemplate Template => '', Arguments => {}

Loads a template. Parses it using arguments if it's not empty.
Returns a tuple (L<RT::Template> object, error message).

Note that even if a template object is returned MIMEObj method
may return undef for empty templates.

=cut

sub PrepareEmailUsingTemplate {
    my %args = (
        Template => '',
        Arguments => {},
        @_
    );

    my $template = RT::Template->new( RT->SystemUser );
    $template->LoadGlobalTemplate( $args{'Template'} );
    unless ( $template->id ) {
        return (undef, "Couldn't load template '". $args{'Template'} ."'");
    }
    return $template if $template->IsEmpty;

    my ($status, $msg) = $template->Parse( %{ $args{'Arguments'} } );
    return (undef, $msg) unless $status;

    return $template;
}

=head2 SendEmailUsingTemplate Template => '', Arguments => {}, From => CorrespondAddress, To => '', Cc => '', Bcc => ''

Sends email using a template, takes name of template, arguments for it and recipients.

=cut

sub SendEmailUsingTemplate {
    my %args = (
        Template => '',
        Arguments => {},
        To => undef,
        Cc => undef,
        Bcc => undef,
        From => RT->Config->Get('CorrespondAddress'),
        InReplyTo => undef,
        ExtraHeaders => {},
        @_
    );

    my ($template, $msg) = PrepareEmailUsingTemplate( %args );
    return (0, $msg) unless $template;

    my $mail = $template->MIMEObj;
    unless ( $mail ) {
        $RT::Logger->info("Message is not sent as template #". $template->id ." is empty");
        return -1;
    }

    $mail->head->replace( $_ => Encode::encode( "UTF-8", $args{ $_ } ) )
        foreach grep defined $args{$_}, qw(To Cc Bcc From);

    $mail->head->replace( $_ => Encode::encode( "UTF-8", $args{ExtraHeaders}{$_} ) )
        foreach keys %{ $args{ExtraHeaders} };

    SetInReplyTo( Message => $mail, InReplyTo => $args{'InReplyTo'} );

    return SendEmail( Entity => $mail );
}

=head2 GetForwardFrom Ticket => undef, Transaction => undef

Resolve the From field to use in forward mail

=cut

sub GetForwardFrom {
    my %args   = ( Ticket => undef, Transaction => undef, @_ );
    my $txn    = $args{Transaction};
    my $ticket = $args{Ticket} || $txn->Object;

    if ( RT->Config->Get('ForwardFromUser') ) {
        return ( $txn || $ticket )->CurrentUser->EmailAddress;
    }
    else {
        return $ticket->QueueObj->CorrespondAddress
          || RT->Config->Get('CorrespondAddress');
    }
}

=head2 GetForwardAttachments Ticket => undef, Transaction => undef

Resolve the Attachments to forward

=cut

sub GetForwardAttachments {
    my %args   = ( Ticket => undef, Transaction => undef, @_ );
    my $txn    = $args{Transaction};
    my $ticket = $args{Ticket} || $txn->Object;

    my $attachments = RT::Attachments->new( $ticket->CurrentUser );
    if ($txn) {
        $attachments->Limit( FIELD => 'TransactionId', VALUE => $txn->id );
    }
    else {
        $attachments->LimitByTicket( $ticket->id );
        $attachments->Limit(
            ALIAS         => $attachments->TransactionAlias,
            FIELD         => 'Type',
            OPERATOR      => 'IN',
            VALUE         => [ qw(Create Correspond) ],
        );
    }
    return $attachments;
}


=head2 SignEncrypt Entity => undef, Sign => 0, Encrypt => 0

Signs and encrypts message using L<RT::Crypt>, but as well handle errors
with users' keys.

If a recipient has no key or has other problems with it, then the
unction sends a error to him using 'Error: public key' template.
Also, notifies RT's owner using template 'Error to RT owner: public key'
to inform that there are problems with users' keys. Then we filter
all bad recipients and retry.

Returns 1 on success, 0 on error and -1 if all recipients are bad and
had been filtered out.

=cut

sub SignEncrypt {
    my %args = (
        Entity => undef,
        Sign => 0,
        Encrypt => 0,
        @_
    );
    return 1 unless $args{'Sign'} || $args{'Encrypt'};

    my $msgid = Encode::decode( "UTF-8", $args{'Entity'}->head->get('Message-ID') || '' );
    chomp $msgid;

    $RT::Logger->debug("$msgid Signing message") if $args{'Sign'};
    $RT::Logger->debug("$msgid Encrypting message") if $args{'Encrypt'};

    my %res = RT::Crypt->SignEncrypt( %args );
    return 1 unless $res{'exit_code'};

    my @status = RT::Crypt->ParseStatus(
        Protocol => $res{'Protocol'}, Status => $res{'status'},
    );

    my @bad_recipients;
    foreach my $line ( @status ) {
        # if the passphrase fails, either you have a bad passphrase
        # or gpg-agent has died.  That should get caught in Create and
        # Update, but at least throw an error here
        if (($line->{'Operation'}||'') eq 'PassphraseCheck'
            && $line->{'Status'} =~ /^(?:BAD|MISSING)$/ ) {
            $RT::Logger->error( "$line->{'Status'} PASSPHRASE: $line->{'Message'}" );
            return 0;
        }
        next unless ($line->{'Operation'}||'') eq 'RecipientsCheck';
        next if $line->{'Status'} eq 'DONE';
        $RT::Logger->error( $line->{'Message'} );
        push @bad_recipients, $line;
    }
    return 0 unless @bad_recipients;

    $_->{'AddressObj'} = (Email::Address->parse( $_->{'Recipient'} ))[0]
        foreach @bad_recipients;

    foreach my $recipient ( @bad_recipients ) {
        my $status = SendEmailUsingTemplate(
            To        => $recipient->{'AddressObj'}->address,
            Template  => 'Error: public key',
            Arguments => {
                %$recipient,
                TicketObj      => $args{'Ticket'},
                TransactionObj => $args{'Transaction'},
            },
        );
        unless ( $status ) {
            $RT::Logger->error("Couldn't send 'Error: public key'");
        }
    }

    my $status = SendEmailUsingTemplate(
        To        => RT->Config->Get('OwnerEmail'),
        Template  => 'Error to RT owner: public key',
        Arguments => {
            BadRecipients  => \@bad_recipients,
            TicketObj      => $args{'Ticket'},
            TransactionObj => $args{'Transaction'},
        },
    );
    unless ( $status ) {
        $RT::Logger->error("Couldn't send 'Error to RT owner: public key'");
    }

    DeleteRecipientsFromHead(
        $args{'Entity'}->head,
        map $_->{'AddressObj'}->address, @bad_recipients
    );

    unless ( $args{'Entity'}->head->get('To')
          || $args{'Entity'}->head->get('Cc')
          || $args{'Entity'}->head->get('Bcc') )
    {
        $RT::Logger->debug("$msgid No recipients that have public key, not sending");
        return -1;
    }

    # redo without broken recipients
    %res = RT::Crypt->SignEncrypt( %args );
    return 0 if $res{'exit_code'};

    return 1;
}

use MIME::Words ();

=head2 EncodeToMIME

Takes a hash with a String and a Charset. Returns the string encoded
according to RFC2047, using B (base64 based) encoding.

String must be a perl string, octets are returned.

If Charset is not provided then $EmailOutputEncoding config option
is used, or "latin-1" if that is not set.

=cut

sub EncodeToMIME {
    my %args = (
        String => undef,
        Charset  => undef,
        @_
    );
    my $value = $args{'String'};
    return $value unless $value; # 0 is perfect ascii
    my $charset  = $args{'Charset'} || RT->Config->Get('EmailOutputEncoding');
    my $encoding = 'B';

    # using RFC2047 notation, sec 2.
    # encoded-word = "=?" charset "?" encoding "?" encoded-text "?="

    # An 'encoded-word' may not be more than 75 characters long
    #
    # MIME encoding increases 4/3*(number of bytes), and always in multiples
    # of 4. Thus we have to find the best available value of bytes available
    # for each chunk.
    #
    # First we get the integer max which max*4/3 would fit on space.
    # Then we find the greater multiple of 3 lower or equal than $max.
    my $max = int(
        (   ( 75 - length( '=?' . $charset . '?' . $encoding . '?' . '?=' ) )
            * 3
        ) / 4
    );
    $max = int( $max / 3 ) * 3;

    chomp $value;

    if ( $max <= 0 ) {

        # gives an error...
        $RT::Logger->crit("Can't encode! Charset or encoding too big.");
        return ($value);
    }

    return ($value) if $value =~ /^(?:[\t\x20-\x7e]|\x0D*\x0A[ \t])+$/s;

    $value =~ s/\s+$//;

    my ( $tmp, @chunks ) = ( '', () );
    while ( length $value ) {
        my $char = substr( $value, 0, 1, '' );
        my $octets = Encode::encode( $charset, $char );
        if ( length($tmp) + length($octets) > $max ) {
            push @chunks, $tmp;
            $tmp = '';
        }
        $tmp .= $octets;
    }
    push @chunks, $tmp if length $tmp;

    # encode an join chuncks
    $value = join "\n ",
        map MIME::Words::encode_mimeword( $_, $encoding, $charset ),
        @chunks;
    return ($value);
}

sub CreateUser {
    my ( $Username, $Address, $Name, $ErrorsTo, $entity ) = @_;

    my $NewUser = RT::User->new( RT->SystemUser );

    my ( $Val, $Message ) = $NewUser->Create(
        Name => ( $Username || $Address ),
        EmailAddress => $Address,
        RealName     => $Name,
        Password     => undef,
        Privileged   => 0,
        Comments     => 'Autocreated on ticket submission',
    );

    unless ($Val) {

        # Deal with the race condition of two account creations at once
        if ($Username) {
            $NewUser->LoadByName($Username);
        }

        unless ( $NewUser->Id ) {
            $NewUser->LoadByEmail($Address);
        }

        unless ( $NewUser->Id ) {
            MailError(
                To          => $ErrorsTo,
                Subject     => "User could not be created",
                Explanation =>
                    "User creation failed in mailgateway: $Message",
                MIMEObj  => $entity,
                LogLevel => 'crit',
            );
        }
    }

    #Load the new user object
    my $CurrentUser = RT::CurrentUser->new;
    $CurrentUser->LoadByEmail( $Address );

    unless ( $CurrentUser->id ) {
        $RT::Logger->warning(
            "Couldn't load user '$Address'." . "giving up" );
        MailError(
            To          => $ErrorsTo,
            Subject     => "User could not be loaded",
            Explanation =>
                "User  '$Address' could not be loaded in the mail gateway",
            MIMEObj  => $entity,
            LogLevel => 'crit'
        );
    }

    return $CurrentUser;
}



=head2 ParseCcAddressesFromHead HASH

Takes a hash containing QueueObj, Head and CurrentUser objects.
Returns a list of all email addresses in the To and Cc
headers b<except> the current Queue's email addresses, the CurrentUser's
email address  and anything that the configuration sub RT::IsRTAddress matches.

=cut

sub ParseCcAddressesFromHead {
    my %args = (
        Head        => undef,
        QueueObj    => undef,
        CurrentUser => undef,
        @_
    );

    my $current_address = lc $args{'CurrentUser'}->EmailAddress;
    my $user = $args{'CurrentUser'}->UserObj;

    return
        grep {  $_ ne $current_address 
                && !RT::EmailParser->IsRTAddress( $_ )
                && !IgnoreCcAddress( $_ )
             }
        map lc $user->CanonicalizeEmailAddress( $_->address ),
        map RT::EmailParser->CleanupAddresses( Email::Address->parse(
              Encode::decode( "UTF-8", $args{'Head'}->get( $_ ) ) ) ),
        qw(To Cc);
}

=head2 IgnoreCcAddress ADDRESS

Returns true if ADDRESS matches the $IgnoreCcRegexp config variable.

=cut

sub IgnoreCcAddress {
    my $address = shift;
    if ( my $address_re = RT->Config->Get('IgnoreCcRegexp') ) {
        return 1 if $address =~ /$address_re/i;
    }
    return undef;
}

=head2 ParseSenderAddressFromHead HEAD

Takes a MIME::Header object. Returns (user@host, friendly name, errors)
where the first two values are the From (evaluated in order of
Reply-To:, From:, Sender).

A list of error messages may be returned even when a Sender value is
found, since it could be a parse error for another (checked earlier)
sender field. In this case, the errors aren't fatal, but may be useful
to investigate the parse failure.

=cut

sub ParseSenderAddressFromHead {
    my $head = shift;
    my @sender_headers = ('Reply-To', 'From', 'Sender');
    my @errors;  # Accumulate any errors

    #Figure out who's sending this message.
    foreach my $header ( @sender_headers ) {
        my $addr_line = Encode::decode( "UTF-8", $head->get($header) ) || next;
        my ($addr, $name) = ParseAddressFromHeader( $addr_line );
        # only return if the address is not empty
        return ($addr, $name, @errors) if $addr;

        chomp $addr_line;
        push @errors, "$header: $addr_line";
    }

    return (undef, undef, @errors);
}

=head2 ParseErrorsToAddressFromHead HEAD

Takes a MIME::Header object. Return a single value : user@host
of the From (evaluated in order of Return-path:,Errors-To:,Reply-To:,
From:, Sender)

=cut

sub ParseErrorsToAddressFromHead {
    my $head = shift;

    #Figure out who's sending this message.

    foreach my $header ( 'Errors-To', 'Reply-To', 'From', 'Sender' ) {

        # If there's a header of that name
        my $headerobj = Encode::decode( "UTF-8", $head->get($header) );
        if ($headerobj) {
            my ( $addr, $name ) = ParseAddressFromHeader($headerobj);

            # If it's got actual useful content...
            return ($addr) if ($addr);
        }
    }
}



=head2 ParseAddressFromHeader ADDRESS

Takes an address from C<$head->get('Line')> and returns a tuple: user@host, friendly name

=cut

sub ParseAddressFromHeader {
    my $Addr = shift;

    # Some broken mailers send:  ""Vincent, Jesse"" <jesse@fsck.com>. Hate
    $Addr =~ s/\"\"(.*?)\"\"/\"$1\"/g;
    my @Addresses = RT::EmailParser->ParseEmailAddress($Addr);

    my ($AddrObj) = grep ref $_, @Addresses;
    unless ( $AddrObj ) {
        return ( undef, undef );
    }

    return ( $AddrObj->address, $AddrObj->phrase );
}

=head2 DeleteRecipientsFromHead HEAD RECIPIENTS

Gets a head object and list of addresses.
Deletes addresses from To, Cc or Bcc fields.

=cut

sub DeleteRecipientsFromHead {
    my $head = shift;
    my %skip = map { lc $_ => 1 } @_;

    foreach my $field ( qw(To Cc Bcc) ) {
        $head->replace( $field => Encode::encode( "UTF-8",
            join ', ', map $_->format, grep !$skip{ lc $_->address },
                Email::Address->parse( Encode::decode( "UTF-8", $head->get( $field ) ) ) )
        );
    }
}

sub GenMessageId {
    my %args = (
        Ticket      => undef,
        Scrip       => undef,
        ScripAction => undef,
        @_
    );
    my $org = RT->Config->Get('Organization');
    my $ticket_id = ( ref $args{'Ticket'}? $args{'Ticket'}->id : $args{'Ticket'} ) || 0;
    my $scrip_id = ( ref $args{'Scrip'}? $args{'Scrip'}->id : $args{'Scrip'} ) || 0;
    my $sent = ( ref $args{'ScripAction'}? $args{'ScripAction'}->{'_Message_ID'} : 0 ) || 0;

    return "<rt-". $RT::VERSION ."-". $$ ."-". CORE::time() ."-". int(rand(2000)) .'.'
        . $ticket_id ."-". $scrip_id ."-". $sent ."@". $org .">" ;
}

sub SetInReplyTo {
    my %args = (
        Message   => undef,
        InReplyTo => undef,
        Ticket    => undef,
        @_
    );
    return unless $args{'Message'} && $args{'InReplyTo'};

    my $get_header = sub {
        my @res;
        if ( $args{'InReplyTo'}->isa('MIME::Entity') ) {
            @res = map {Encode::decode("UTF-8", $_)} $args{'InReplyTo'}->head->get( shift );
        } else {
            @res = $args{'InReplyTo'}->GetHeader( shift ) || '';
        }
        return grep length, map { split /\s+/m, $_ } grep defined, @res;
    };

    my @id = $get_header->('Message-ID');
    #XXX: custom header should begin with X- otherwise is violation of the standard
    my @rtid = $get_header->('RT-Message-ID');
    my @references = $get_header->('References');
    unless ( @references ) {
        @references = $get_header->('In-Reply-To');
    }
    push @references, @id, @rtid;
    if ( $args{'Ticket'} ) {
        my $pseudo_ref = PseudoReference( $args{'Ticket'} );
        push @references, $pseudo_ref unless grep $_ eq $pseudo_ref, @references;
    }
    splice @references, 4, -6
        if @references > 10;

    my $mail = $args{'Message'};
    $mail->head->replace( 'In-Reply-To' => Encode::encode( "UTF-8", join ' ', @rtid? (@rtid) : (@id)) ) if @id || @rtid;
    $mail->head->replace( 'References' => Encode::encode( "UTF-8", join ' ', @references) );
}

sub PseudoReference {
    my $ticket = shift;
    return '<RT-Ticket-'. $ticket->id .'@'. RT->Config->Get('Organization') .'>';
}

=head2 ExtractTicketId

Passed a MIME::Entity.  Returns a ticket id or undef to signal 'new ticket'.

This is a great entry point if you need to customize how ticket ids are
handled for your site. RT-Extension-RepliesToResolved demonstrates one
possible use for this extension.

If the Subject of this ticket is modified, it will be reloaded by the
mail gateway code before Ticket creation.

=cut

sub ExtractTicketId {
    my $entity = shift;

    my $subject = Encode::decode( "UTF-8", $entity->head->get('Subject') || '' );
    chomp $subject;
    return ParseTicketId( $subject );
}

=head2 ParseTicketId

Takes a string and searches for [subjecttag #id]

Returns the id if a match is found.  Otherwise returns undef.

=cut

sub ParseTicketId {
    my $Subject = shift;

    my $rtname = RT->Config->Get('rtname');
    my $test_name = RT->Config->Get('EmailSubjectTagRegex') || qr/\Q$rtname\E/i;

    # We use @captures and pull out the last capture value to guard against
    # someone using (...) instead of (?:...) in $EmailSubjectTagRegex.
    my $id;
    if ( my @captures = $Subject =~ /\[$test_name\s+\#(\d+)\s*\]/i ) {
        $id = $captures[-1];
    } else {
        foreach my $tag ( RT->System->SubjectTag ) {
            next unless my @captures = $Subject =~ /\[\Q$tag\E\s+\#(\d+)\s*\]/i;
            $id = $captures[-1];
            last;
        }
    }
    return undef unless $id;

    $RT::Logger->debug("Found a ticket ID. It's $id");
    return $id;
}

sub AddSubjectTag {
    my $subject = shift;
    my $ticket  = shift;
    unless ( ref $ticket ) {
        my $tmp = RT::Ticket->new( RT->SystemUser );
        $tmp->Load( $ticket );
        $ticket = $tmp;
    }
    my $id = $ticket->id;
    my $queue_tag = $ticket->QueueObj->SubjectTag;

    my $tag_re = RT->Config->Get('EmailSubjectTagRegex');
    unless ( $tag_re ) {
        my $tag = $queue_tag || RT->Config->Get('rtname');
        $tag_re = qr/\Q$tag\E/;
    } elsif ( $queue_tag ) {
        $tag_re = qr/$tag_re|\Q$queue_tag\E/;
    }
    return $subject if $subject =~ /\[$tag_re\s+#$id\]/;

    $subject =~ s/(\r\n|\n|\s)/ /g;
    chomp $subject;
    return "[". ($queue_tag || RT->Config->Get('rtname')) ." #$id] $subject";
}


=head2 Gateway ARGSREF


Takes parameters:

    action
    queue
    message


This performs all the "guts" of the mail rt-mailgate program, and is
designed to be called from the web interface with a message, user
object, and so on.

Can also take an optional 'ticket' parameter; this ticket id overrides
any ticket id found in the subject.

Returns:

    An array of:

    (status code, message, optional ticket object)

    status code is a numeric value.

      for temporary failures, the status code should be -75

      for permanent failures which are handled by RT, the status code
      should be 0

      for succces, the status code should be 1



=cut

sub _LoadPlugins {
    my @mail_plugins = @_;

    my @res;
    foreach my $plugin (@mail_plugins) {
        if ( ref($plugin) eq "CODE" ) {
            push @res, $plugin;
        } elsif ( !ref $plugin ) {
            my $Class = $plugin;
            $Class = "RT::Interface::Email::" . $Class
                unless $Class =~ /^RT::/;
            $Class->require or
                do { $RT::Logger->error("Couldn't load $Class: $@"); next };

            no strict 'refs';
            unless ( defined *{ $Class . "::GetCurrentUser" }{CODE} ) {
                $RT::Logger->crit( "No GetCurrentUser code found in $Class module");
                next;
            }
            push @res, $Class;
        } else {
            $RT::Logger->crit( "$plugin - is not class name or code reference");
        }
    }
    return @res;
}

sub Gateway {
    my $argsref = shift;
    my %args    = (
        action  => 'correspond',
        queue   => '1',
        ticket  => undef,
        message => undef,
        %$argsref
    );

    my $SystemTicket;
    my $Right;

    # Validate the action
    my ( $status, @actions ) = IsCorrectAction( $args{'action'} );
    unless ($status) {
        return (
            -75,
            "Invalid 'action' parameter "
                . $actions[0]
                . " for queue "
                . $args{'queue'},
            undef
        );
    }

    my $parser = RT::EmailParser->new();
    $parser->SmartParseMIMEEntityFromScalar(
        Message => $args{'message'},
        Decode => 0,
        Exact => 1,
    );

    my $Message = $parser->Entity();
    unless ($Message) {
        MailError(
            Subject     => "RT Bounce: Unparseable message",
            Explanation => "RT couldn't process the message below",
            Attach      => $args{'message'}
        );

        return ( 0,
            "Failed to parse this message. Something is likely badly wrong with the message"
        );
    }

    my @mail_plugins = grep $_, RT->Config->Get('MailPlugins');
    push @mail_plugins, "Auth::MailFrom" unless @mail_plugins;
    @mail_plugins = _LoadPlugins( @mail_plugins );

    #Set up a queue object
    my $SystemQueueObj = RT::Queue->new( RT->SystemUser );
    $SystemQueueObj->Load( $args{'queue'} );

    my %skip_plugin;
    foreach my $class( grep !ref, @mail_plugins ) {
        # check if we should apply filter before decoding
        my $check_cb = do {
            no strict 'refs';
            *{ $class . "::ApplyBeforeDecode" }{CODE};
        };
        next unless defined $check_cb;
        next unless $check_cb->(
            Message       => $Message,
            RawMessageRef => \$args{'message'},
            Queue         => $SystemQueueObj,
            Actions       => \@actions,
        );

        $skip_plugin{ $class }++;

        my $Code = do {
            no strict 'refs';
            *{ $class . "::GetCurrentUser" }{CODE};
        };
        my ($status, $msg) = $Code->(
            Message       => $Message,
            RawMessageRef => \$args{'message'},
            Queue         => $SystemQueueObj,
            Actions       => \@actions,
        );
        next if $status > 0;

        if ( $status == -2 ) {
            return (1, $msg, undef);
        } elsif ( $status == -1 ) {
            return (0, $msg, undef);
        }
    }
    @mail_plugins = grep !$skip_plugin{"$_"}, @mail_plugins;
    $parser->_DecodeBodies;
    $parser->RescueOutlook;
    $parser->_PostProcessNewEntity;

    my $head = $Message->head;
    my $ErrorsTo = ParseErrorsToAddressFromHead( $head );
    my $Sender = (ParseSenderAddressFromHead( $head ))[0];
    my $From = Encode::decode( "UTF-8", $head->get("From") );
    chomp $From if defined $From;

    my $MessageId = Encode::decode( "UTF-8", $head->get('Message-ID') )
        || "<no-message-id-". time . rand(2000) .'@'. RT->Config->Get('Organization') .'>';

    #Pull apart the subject line
    my $Subject = Encode::decode( "UTF-8", $head->get('Subject') || '');
    chomp $Subject;
    
    # Lets check for mail loops of various sorts.
    my ($should_store_machine_generated_message, $IsALoop, $result);
    ( $should_store_machine_generated_message, $ErrorsTo, $result, $IsALoop ) =
      _HandleMachineGeneratedMail(
        Message  => $Message,
        ErrorsTo => $ErrorsTo,
        Subject  => $Subject,
        MessageId => $MessageId
    );

    # Do not pass loop messages to MailPlugins, to make sure the loop
    # is broken, unless $RT::StoreLoops is set.
    if ($IsALoop && !$should_store_machine_generated_message) {
        return ( 0, $result, undef );
    }
    # }}}

    $args{'ticket'} ||= ExtractTicketId( $Message );

    # ExtractTicketId may have been overridden, and edited the Subject
    my $NewSubject = Encode::decode( "UTF-8", $Message->head->get('Subject') );
    chomp $NewSubject;

    $SystemTicket = RT::Ticket->new( RT->SystemUser );
    $SystemTicket->Load( $args{'ticket'} ) if ( $args{'ticket'} ) ;
    if ( $SystemTicket->id ) {
        $Right = 'ReplyToTicket';
    } else {
        $Right = 'CreateTicket';
    }

    # We can safely have no queue of we have a known-good ticket
    unless ( $SystemTicket->id || $SystemQueueObj->id ) {
        return ( -75, "RT couldn't find the queue: " . $args{'queue'}, undef );
    }

    my ($AuthStat, $CurrentUser, $error) = GetAuthenticationLevel(
        MailPlugins   => \@mail_plugins,
        Actions       => \@actions,
        Message       => $Message,
        RawMessageRef => \$args{message},
        SystemTicket  => $SystemTicket,
        SystemQueue   => $SystemQueueObj,
    );

    # If authentication fails and no new user was created, get out.
    if ( !$CurrentUser || !$CurrentUser->id || $AuthStat == -1 ) {

        # If the plugins refused to create one, they lose.
        unless ( $AuthStat == -1 ) {
            _NoAuthorizedUserFound(
                Right     => $Right,
                Message   => $Message,
                Requestor => $ErrorsTo,
                Queue     => $args{'queue'}
            );

        }
        return ( 0, "Could not load a valid user", undef );
    }

    # If we got a user, but they don't have the right to say things
    if ( $AuthStat == 0 ) {
        MailError(
            To          => $ErrorsTo,
            Subject     => "Permission Denied",
            Explanation =>
                "You do not have permission to communicate with RT",
            MIMEObj => $Message
        );
        return (
            0,
            ($CurrentUser->EmailAddress || $CurrentUser->Name)
            . " ($Sender) tried to submit a message to "
                . $args{'Queue'}
                . " without permission.",
            undef
        );
    }


    unless ($should_store_machine_generated_message) {
        return ( 0, $result, undef );
    }

    $head->replace('X-RT-Interface' => 'Email');

    # if plugin's updated SystemTicket then update arguments
    $args{'ticket'} = $SystemTicket->Id if $SystemTicket && $SystemTicket->Id;

    my $Ticket = RT::Ticket->new($CurrentUser);

    if ( !$args{'ticket'} && grep /^(comment|correspond)$/, @actions )
    {

        my @Cc;
        my @Requestors = ( $CurrentUser->id );

        if (RT->Config->Get('ParseNewMessageForTicketCcs')) {
            @Cc = ParseCcAddressesFromHead(
                Head        => $head,
                CurrentUser => $CurrentUser,
                QueueObj    => $SystemQueueObj
            );
        }

        my ( $id, $Transaction, $ErrStr ) = $Ticket->Create(
            Queue     => $SystemQueueObj->Id,
            Subject   => $NewSubject,
            Requestor => \@Requestors,
            Cc        => \@Cc,
            MIMEObj   => $Message
        );
        if ( $id == 0 ) {
            MailError(
                To          => $ErrorsTo,
                Subject     => "Ticket creation failed: $Subject",
                Explanation => $ErrStr,
                MIMEObj     => $Message
            );
            return ( 0, "Ticket creation From: $From failed: $ErrStr", $Ticket );
        }

        # strip comments&corresponds from the actions we don't need
        # to record them if we've created the ticket just now
        @actions = grep !/^(comment|correspond)$/, @actions;
        $args{'ticket'} = $id;

    } elsif ( $args{'ticket'} ) {

        $Ticket->Load( $args{'ticket'} );
        unless ( $Ticket->Id ) {
            my $error = "Could not find a ticket with id " . $args{'ticket'};
            MailError(
                To          => $ErrorsTo,
                Subject     => "Message not recorded: $Subject",
                Explanation => $error,
                MIMEObj     => $Message
            );

            return ( 0, $error );
        }
        $args{'ticket'} = $Ticket->id;
    } else {
        return ( 1, "Success", $Ticket );
    }

    # }}}

    my $unsafe_actions = RT->Config->Get('UnsafeEmailCommands');
    foreach my $action (@actions) {

        #   If the action is comment, add a comment.
        if ( $action =~ /^(?:comment|correspond)$/i ) {
            my $method = ucfirst lc $action;
            my ( $status, $msg ) = $Ticket->$method( MIMEObj => $Message );
            unless ($status) {

                #Warn the sender that we couldn't actually submit the comment.
                MailError(
                    To          => $ErrorsTo,
                    Subject     => "Message not recorded ($method): $Subject",
                    Explanation => $msg,
                    MIMEObj     => $Message
                );
                return ( 0, "Message From: $From not recorded: $msg", $Ticket );
            }
        } elsif ($unsafe_actions) {
            my ( $status, $msg ) = _RunUnsafeAction(
                Action      => $action,
                ErrorsTo    => $ErrorsTo,
                Message     => $Message,
                Ticket      => $Ticket,
                CurrentUser => $CurrentUser,
            );
            return ($status, $msg, $Ticket) unless $status == 1;
        }
    }
    return ( 1, "Success", $Ticket );
}

=head2 GetAuthenticationLevel

    # Authentication Level
    # -1 - Get out.  this user has been explicitly declined
    # 0 - User may not do anything (Not used at the moment)
    # 1 - Normal user
    # 2 - User is allowed to specify status updates etc. a la enhanced-mailgate

=cut

sub GetAuthenticationLevel {
    my %args = (
        MailPlugins   => [],
        Actions       => [],
        Message       => undef,
        RawMessageRef => undef,
        SystemTicket  => undef,
        SystemQueue   => undef,
        @_,
    );

    my ( $CurrentUser, $AuthStat, $error );

    # Initalize AuthStat so comparisons work correctly
    $AuthStat = -9999999;

    # if plugin returns AuthStat -2 we skip action
    # NOTE: this is experimental API and it would be changed
    my %skip_action = ();

    # Since this needs loading, no matter what
    foreach (@{ $args{MailPlugins} }) {
        my ($Code, $NewAuthStat);
        if ( ref($_) eq "CODE" ) {
            $Code = $_;
        } else {
            no strict 'refs';
            $Code = *{ $_ . "::GetCurrentUser" }{CODE};
        }

        foreach my $action (@{ $args{Actions} }) {
            ( $CurrentUser, $NewAuthStat ) = $Code->(
                Message       => $args{Message},
                RawMessageRef => $args{RawMessageRef},
                CurrentUser   => $CurrentUser,
                AuthLevel     => $AuthStat,
                Action        => $action,
                Ticket        => $args{SystemTicket},
                Queue         => $args{SystemQueue},
            );

# You get the highest level of authentication you were assigned, unless you get the magic -1
# If a module returns a "-1" then we discard the ticket, so.
            $AuthStat = $NewAuthStat
                if ( $NewAuthStat > $AuthStat or $NewAuthStat == -1 or $NewAuthStat == -2 );

            last if $AuthStat == -1;
            $skip_action{$action}++ if $AuthStat == -2;
        }

        # strip actions we should skip
        @{$args{Actions}} = grep !$skip_action{$_}, @{$args{Actions}}
            if $AuthStat == -2;
        last unless @{$args{Actions}};

        last if $AuthStat == -1;
    }

    return $AuthStat if !wantarray;

    return ($AuthStat, $CurrentUser, $error);
}

sub _RunUnsafeAction {
    my %args = (
        Action      => undef,
        ErrorsTo    => undef,
        Message     => undef,
        Ticket      => undef,
        CurrentUser => undef,
        @_
    );

    my $From = Encode::decode( "UTF-8", $args{Message}->head->get("From") );

    if ( $args{'Action'} =~ /^take$/i ) {
        my ( $status, $msg ) = $args{'Ticket'}->SetOwner( $args{'CurrentUser'}->id );
        unless ($status) {
            MailError(
                To          => $args{'ErrorsTo'},
                Subject     => "Ticket not taken",
                Explanation => $msg,
                MIMEObj     => $args{'Message'}
            );
            return ( 0, "Ticket not taken, by email From: $From" );
        }
    } elsif ( $args{'Action'} =~ /^resolve$/i ) {
        my $new_status = $args{'Ticket'}->FirstInactiveStatus;
        if ($new_status) {
            my ( $status, $msg ) = $args{'Ticket'}->SetStatus($new_status);
            unless ($status) {

                #Warn the sender that we couldn't actually submit the comment.
                MailError(
                    To          => $args{'ErrorsTo'},
                    Subject     => "Ticket not resolved",
                    Explanation => $msg,
                    MIMEObj     => $args{'Message'}
                );
                return ( 0, "Ticket not resolved, by email From: $From" );
            }
        }
    } else {
        return ( 0, "Not supported unsafe action $args{'Action'}, by email From: $From", $args{'Ticket'} );
    }
    return ( 1, "Success" );
}

=head2 _NoAuthorizedUserFound

Emails the RT Owner and the requestor when the auth plugins return "No auth user found"

=cut

sub _NoAuthorizedUserFound {
    my %args = (
        Right     => undef,
        Message   => undef,
        Requestor => undef,
        Queue     => undef,
        @_
    );

    # Notify the RT Admin of the failure.
    MailError(
        To          => RT->Config->Get('OwnerEmail'),
        Subject     => "Could not load a valid user",
        Explanation => <<EOT,
RT could not load a valid user, and RT's configuration does not allow
for the creation of a new user for this email (@{[$args{Requestor}]}).

You might need to grant 'Everyone' the right '@{[$args{Right}]}' for the
queue @{[$args{'Queue'}]}.

EOT
        MIMEObj  => $args{'Message'},
        LogLevel => 'error'
    );

    # Also notify the requestor that his request has been dropped.
    if ($args{'Requestor'} ne RT->Config->Get('OwnerEmail')) {
    MailError(
        To          => $args{'Requestor'},
        Subject     => "Could not load a valid user",
        Explanation => <<EOT,
RT could not load a valid user, and RT's configuration does not allow
for the creation of a new user for your email.

EOT
        MIMEObj  => $args{'Message'},
        LogLevel => 'error'
    );
    }
}

=head2 _HandleMachineGeneratedMail

Takes named params:
    Message
    ErrorsTo
    Subject

Checks the message to see if it's a bounce, if it looks like a loop, if it's autogenerated, etc.
Returns a triple of ("Should we continue (boolean)", "New value for $ErrorsTo", "Status message",
"This message appears to be a loop (boolean)" );

=cut

sub _HandleMachineGeneratedMail {
    my %args = ( Message => undef, ErrorsTo => undef, Subject => undef, MessageId => undef, @_ );
    my $head = $args{'Message'}->head;
    my $ErrorsTo = $args{'ErrorsTo'};

    my $IsBounce = CheckForBounce($head);

    my $IsAutoGenerated = CheckForAutoGenerated($head);

    my $IsSuspiciousSender = CheckForSuspiciousSender($head);

    my $IsALoop = CheckForLoops($head);

    my $SquelchReplies = 0;

    my $owner_mail = RT->Config->Get('OwnerEmail');

    #If the message is autogenerated, we need to know, so we can not
    # send mail to the sender
    if ( $IsBounce || $IsSuspiciousSender || $IsAutoGenerated || $IsALoop ) {
        $SquelchReplies = 1;
        $ErrorsTo       = $owner_mail;
    }

    # Warn someone if it's a loop, before we drop it on the ground
    if ($IsALoop) {
        $RT::Logger->crit("RT Received mail (".$args{MessageId}.") from itself.");

        #Should we mail it to RTOwner?
        if ( RT->Config->Get('LoopsToRTOwner') ) {
            MailError(
                To          => $owner_mail,
                Subject     => "RT Bounce: ".$args{'Subject'},
                Explanation => "RT thinks this message may be a bounce",
                MIMEObj     => $args{Message}
            );
        }

        #Do we actually want to store it?
        return ( 0, $ErrorsTo, "Message Bounced", $IsALoop )
            unless RT->Config->Get('StoreLoops');
    }

    # Squelch replies if necessary
    # Don't let the user stuff the RT-Squelch-Replies-To header.
    if ( $head->get('RT-Squelch-Replies-To') ) {
        $head->replace(
            'RT-Relocated-Squelch-Replies-To',
            $head->get('RT-Squelch-Replies-To')
        );
        $head->delete('RT-Squelch-Replies-To');
    }

    if ($SquelchReplies) {

        # Squelch replies to the sender, and also leave a clue to
        # allow us to squelch ALL outbound messages. This way we
        # can punt the logic of "what to do when we get a bounce"
        # to the scrip. We might want to notify nobody. Or just
        # the RT Owner. Or maybe all Privileged watchers.
        my ( $Sender, $junk ) = ParseSenderAddressFromHead($head);
        $head->replace( 'RT-Squelch-Replies-To',    Encode::encode("UTF-8", $Sender ) );
        $head->replace( 'RT-DetectedAutoGenerated', 'true' );
    }
    return ( 1, $ErrorsTo, "Handled machine detection", $IsALoop );
}

=head2 IsCorrectAction

Returns a list of valid actions we've found for this message

=cut

sub IsCorrectAction {
    my $action = shift;
    my @actions = grep $_, split /-/, $action;
    return ( 0, '(no value)' ) unless @actions;
    foreach ( @actions ) {
        return ( 0, $_ ) unless /^(?:comment|correspond|take|resolve)$/;
    }
    return ( 1, @actions );
}

sub _RecordSendEmailFailure {
    my $ticket = shift;
    if ($ticket) {
        $ticket->_NewTransaction(
            Type => "SystemError",
            Data => "Sending the previous mail has failed.  Please contact your admin, they can find more details in the logs.", #loc
            ActivateScrips => 0,
        );
        return 1;
    }
    else {
        $RT::Logger->error( "Can't record send email failure as ticket is missing" );
        return;
    }
}

=head2 ConvertHTMLToText HTML

Takes HTML characters and converts it to plain text characters.
Appropriate for generating a plain text part from an HTML part of an
email.  Returns undef if conversion fails.

=cut

sub ConvertHTMLToText {
    return _HTMLFormatter()->(@_);
}

sub _HTMLFormatter {
    state $formatter;
    return $formatter if defined $formatter;

    my $wanted = RT->Config->Get("HTMLFormatter");

    my @order;
    if ($wanted) {
        @order = ($wanted, "core");
    } else {
        @order = ("w3m", "elinks", "links", "html2text", "lynx", "core");
    }
    # Always fall back to core, even if it is not listed
    for my $prog (@order) {
        if ($prog eq "core") {
            RT->Logger->debug("Using internal Perl HTML -> text conversion");
            require HTML::FormatText::WithLinks::AndTables;
            $formatter = \&_HTMLFormatText;
        } else {
            unless (HTML::FormatExternal->require) {
                RT->Logger->warn("HTML::FormatExternal is not installed; falling back to internal perl formatter")
                    if $wanted;
                next;
            }

            my $path = $prog =~ s{(.*/)}{} ? $1 : undef;
            my $package = "HTML::FormatText::" . ucfirst($prog);
            unless ($package->require) {
                RT->Logger->warn("$prog is not a valid formatter provided by HTML::FormatExternal")
                    if $wanted;
                next;
            }

            if ($path) {
                local $ENV{PATH} = $path;
                local $ENV{HOME} = File::Spec->tmpdir();
                if (not defined $package->program_version) {
                    RT->Logger->warn("Could not find or run external '$prog' HTML formatter in $path$prog")
                        if $wanted;
                    next;
                }
            } else {
                local $ENV{PATH} = '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
                    unless defined $ENV{PATH};
                local $ENV{HOME} = File::Spec->tmpdir();
                if (not defined $package->program_version) {
                    RT->Logger->warn("Could not find or run external '$prog' HTML formatter in \$PATH ($ENV{PATH}) -- you may need to install it or provide the full path")
                        if $wanted;
                    next;
                }
            }

            RT->Logger->debug("Using $prog for HTML -> text conversion");
            $formatter = sub {
                my $html = shift;
                my $text = RT::Util::safe_run_child {
                    local $ENV{PATH} = $path || $ENV{PATH}
                        || '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin';
                    local $ENV{HOME} = File::Spec->tmpdir();
                    $package->format_string(
                        Encode::encode( "UTF-8", $html ),
                        input_charset => "UTF-8",
                        output_charset => "UTF-8",
                        leftmargin => 0, rightmargin => 78
                    );
                };
                $text = Encode::decode( "UTF-8", $text );
                return $text;
            };
        }
        RT->Config->Set( HTMLFormatter => $prog );
        last;
    }
    return $formatter;
}

sub _HTMLFormatText {
    my $html = shift;

    my $text;
    eval {
        $text = HTML::FormatText::WithLinks::AndTables->convert(
            $html => {
                leftmargin      => 0,
                rightmargin     => 78,
                no_rowspacing   => 1,
                before_link     => '',
                after_link      => ' (%l)',
                footnote        => '',
                skip_linked_urls => 1,
                with_emphasis   => 0,
            }
        );
        $text //= '';
    };
    $RT::Logger->error("Failed to downgrade HTML to plain text: $@") if $@;
    return $text;
}


RT::Base->_ImportOverlays();

1;