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package RT::EmailParser;


use base qw/RT::Base/;

use strict;
use warnings;

use Email::Address;
use MIME::Entity;
use MIME::Head;
use MIME::Parser;
use File::Temp qw/tempdir/;

=head1 NAME

  RT::EmailParser - helper functions for parsing parts from incoming
  email messages

=head1 SYNOPSIS


=head1 DESCRIPTION




=head1 METHODS

=head2 new

Returns a new RT::EmailParser object

=cut

sub new  {
  my $proto = shift;
  my $class = ref($proto) || $proto;
  my $self  = {};
  bless ($self, $class);
  return $self;
}


=head2 SmartParseMIMEEntityFromScalar Message => SCALAR_REF [, Decode => BOOL, Exact => BOOL ] }

Parse a message stored in a scalar from scalar_ref.

=cut

sub SmartParseMIMEEntityFromScalar {
    my $self = shift;
    my %args = ( Message => undef, Decode => 1, Exact => 0, @_ );

    eval {
        my ( $fh, $temp_file );
        for ( 1 .. 10 ) {

            # on NFS and NTFS, it is possible that tempfile() conflicts
            # with other processes, causing a race condition. we try to
            # accommodate this by pausing and retrying.
            last
              if ( $fh, $temp_file ) =
              eval { File::Temp::tempfile( undef, UNLINK => 0 ) };
            sleep 1;
        }
        if ($fh) {

            #thank you, windows                      
            binmode $fh;
            $fh->autoflush(1);
            print $fh $args{'Message'};
            close($fh);
            if ( -f $temp_file ) {

                # We have to trust the temp file's name -- untaint it
                $temp_file =~ /(.*)/;
                my $entity = $self->ParseMIMEEntityFromFile( $1, $args{'Decode'}, $args{'Exact'} );
                unlink($1);
                return $entity;
            }
        }
    };

    $self->RescueOutlook;

    #If for some reason we weren't able to parse the message using a temp file
    # try it with a scalar
    if ( $@ || !$self->Entity ) {
        return $self->ParseMIMEEntityFromScalar( $args{'Message'}, $args{'Decode'}, $args{'Exact'} );
    }

}


=head2 ParseMIMEEntityFromSTDIN

Parse a message from standard input

=cut

sub ParseMIMEEntityFromSTDIN {
    my $self = shift;
    return $self->ParseMIMEEntityFromFileHandle(\*STDIN, @_);
}

=head2 ParseMIMEEntityFromScalar  $message

Takes either a scalar or a reference to a scalar which contains a stringified MIME message.
Parses it.

Returns true if it wins.
Returns false if it loses.

=cut

sub ParseMIMEEntityFromScalar {
    my $self = shift;
    return $self->_ParseMIMEEntity( shift, 'parse_data', @_ );
}

=head2 ParseMIMEEntityFromFilehandle *FH

Parses a mime entity from a filehandle passed in as an argument

=cut

sub ParseMIMEEntityFromFileHandle {
    my $self = shift;
    return $self->_ParseMIMEEntity( shift, 'parse', @_ );
}

=head2 ParseMIMEEntityFromFile 

Parses a mime entity from a filename passed in as an argument

=cut

sub ParseMIMEEntityFromFile {
    my $self = shift;
    return $self->_ParseMIMEEntity( shift, 'parse_open', @_ );
}


sub _ParseMIMEEntity {
    my $self = shift;
    my $message = shift;
    my $method = shift;
    my $postprocess = (@_ ? shift : 1);
    my $exact = shift;

    # Create a new parser object:
    my $parser = MIME::Parser->new();
    $self->_SetupMIMEParser($parser);
    $parser->decode_bodies(0) if $exact;

    # TODO: XXX 3.0 we really need to wrap this in an eval { }
    unless ( $self->{'entity'} = $parser->$method($message) ) {
        $RT::Logger->crit("Couldn't parse MIME stream and extract the submessages");
        # Try again, this time without extracting nested messages
        $parser->extract_nested_messages(0);
        unless ( $self->{'entity'} = $parser->$method($message) ) {
            $RT::Logger->crit("couldn't parse MIME stream");
            return ( undef);
        }
    }

    $self->_PostProcessNewEntity if $postprocess;

    return $self->{'entity'};
}

sub _DecodeBodies {
    my $self = shift;
    return unless $self->{'entity'};
    
    my @parts = $self->{'entity'}->parts_DFS;
    $self->_DecodeBody($_) foreach @parts;
}

sub _DecodeBody {
    my $self = shift;
    my $entity = shift;

    my $old = $entity->bodyhandle or return;
    return unless $old->is_encoded;

    require MIME::Decoder;
    my $encoding = $entity->head->mime_encoding;
    my $decoder = new MIME::Decoder $encoding;
    unless ( $decoder ) {
        $RT::Logger->error("Couldn't find decoder for '$encoding', switching to binary");
        $old->is_encoded(0);
        return;
    }

    require MIME::Body;
    # XXX: use InCore for now, but later must switch to files
    my $new = new MIME::Body::InCore;
    $new->binmode(1);
    $new->is_encoded(0);

    my $source = $old->open('r') or die "couldn't open body: $!";
    my $destination = $new->open('w') or die "couldn't open body: $!";
    { 
        local $@;
        eval { $decoder->decode($source, $destination) };
        $RT::Logger->error($@) if $@;
    }
    $source->close or die "can't close: $!";
    $destination->close or die "can't close: $!";

    $entity->bodyhandle( $new );
}

=head2 _PostProcessNewEntity

cleans up and postprocesses a newly parsed MIME Entity

=cut

sub _PostProcessNewEntity {
    my $self = shift;

    #Now we've got a parsed mime object. 

    # Unfold headers that are have embedded newlines
    #  Better do this before conversion or it will break
    #  with multiline encoded Subject (RFC2047) (fsck.com #5594)
    $self->Head->unfold;

    # try to convert text parts into utf-8 charset
    RT::I18N::SetMIMEEntityToEncoding($self->{'entity'}, 'utf-8');
}

=head2 ParseCcAddressesFromHead HASHREF

Takes a hashref object 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 RT->Config->Get('RTAddressRegexp') matches.

=cut

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

    my (@Addresses);

    my @ToObjs = Email::Address->parse( $self->Head->get('To') );
    my @CcObjs = Email::Address->parse( $self->Head->get('Cc') );

    foreach my $AddrObj ( @ToObjs, @CcObjs ) {
        my $Address = $AddrObj->address;
        my $user = RT::User->new($RT::SystemUser);
        $Address = $user->CanonicalizeEmailAddress($Address);
        next if lc $args{'CurrentUser'}->EmailAddress eq lc $Address;
        next if $self->IsRTAddress($Address);

        push ( @Addresses, $Address );
    }
    return (@Addresses);
}


=head2 IsRTaddress ADDRESS

Takes a single parameter, an email address. 
Returns true if that address matches the C<RTAddressRegexp> config option.
Returns false, otherwise.


=cut

sub IsRTAddress {
    my $self = shift;
    my $address = shift;

    if ( my $address_re = RT->Config->Get('RTAddressRegexp') ) {
        return $address =~ /$address_re/i ? 1 : undef;
    }

    # we don't warn here, but do in config check
    if ( my $correspond_address = RT->Config->Get('CorrespondAddress') ) {
        return 1 if lc $correspond_address eq lc $address;
    }
    if ( my $comment_address = RT->Config->Get('CommentAddress') ) {
        return 1 if lc $comment_address eq lc $address;
    }

    my $queue = RT::Queue->new( $RT::SystemUser );
    $queue->LoadByCols( CorrespondAddress => $address );
    return 1 if $queue->id;

    $queue->LoadByCols( CommentAddress => $address );
    return 1 if $queue->id;

    return undef;
}


=head2 CullRTAddresses ARRAY

Takes a single argument, an array of email addresses.
Returns the same array with any IsRTAddress()es weeded out.


=cut

sub CullRTAddresses {
    my $self = shift;
    my @addresses= (@_);
    my @addrlist;

    foreach my $addr( @addresses ) {
                                 # We use the class instead of the instance
                                 # because sloppy code calls this method
                                 # without a $self
      push (@addrlist, $addr)    unless RT::EmailParser->IsRTAddress($addr);
    }
    return (@addrlist);
}





# LookupExternalUserInfo is a site-definable method for synchronizing
# incoming users with an external data source. 
#
# This routine takes a tuple of EmailAddress and FriendlyName
#   EmailAddress is the user's email address, ususally taken from
#       an email message's From: header.
#   FriendlyName is a freeform string, ususally taken from the "comment" 
#       portion of an email message's From: header.
#
# If you define an AutoRejectRequest template, RT will use this   
# template for the rejection message.


=head2 LookupExternalUserInfo

 LookupExternalUserInfo is a site-definable method for synchronizing
 incoming users with an external data source. 

 This routine takes a tuple of EmailAddress and FriendlyName
    EmailAddress is the user's email address, ususally taken from
        an email message's From: header.
    FriendlyName is a freeform string, ususally taken from the "comment" 
        portion of an email message's From: header.

 It returns (FoundInExternalDatabase, ParamHash);

   FoundInExternalDatabase must  be set to 1 before return if the user 
   was found in the external database.

   ParamHash is a Perl parameter hash which can contain at least the 
   following fields. These fields are used to populate RT's users 
   database when the user is created.

    EmailAddress is the email address that RT should use for this user.  
    Name is the 'Name' attribute RT should use for this user. 
         'Name' is used for things like access control and user lookups.
    RealName is what RT should display as the user's name when displaying 
         'friendly' names

=cut

sub LookupExternalUserInfo {
  my $self = shift;
  my $EmailAddress = shift;
  my $RealName = shift;

  my $FoundInExternalDatabase = 1;
  my %params;

  #Name is the RT username you want to use for this user.
  $params{'Name'} = $EmailAddress;
  $params{'EmailAddress'} = $EmailAddress;
  $params{'RealName'} = $RealName;

  # See RT's contributed code for examples.
  # http://www.fsck.com/pub/rt/contrib/
  return ($FoundInExternalDatabase, %params);
}

=head2 Head

Return the parsed head from this message

=cut

sub Head {
    my $self = shift;
    return $self->Entity->head;
}

=head2 Entity 

Return the parsed Entity from this message

=cut

sub Entity {
    my $self = shift;
    return $self->{'entity'};
}



=head2 _SetupMIMEParser $parser

A private instance method which sets up a mime parser to do its job

=cut


    ## TODO: Does it make sense storing to disk at all?  After all, we
    ## need to put each msg as an in-core scalar before saving it to
    ## the database, don't we?

    ## At the same time, we should make sure that we nuke attachments 
    ## Over max size and return them

sub _SetupMIMEParser {
    my $self   = shift;
    my $parser = shift;
    
    # Set up output directory for files; we use $RT::VarPath instead
    # of File::Spec->tmpdir (e.g., /tmp) beacuse it isn't always
    # writable.
    my $tmpdir;
    if ( -w $RT::VarPath ) {
        $tmpdir = File::Temp::tempdir( DIR => $RT::VarPath, CLEANUP => 1 );
    } elsif (-w File::Spec->tmpdir) {
        $tmpdir = File::Temp::tempdir( TMPDIR => 1, CLEANUP => 1 );
    } else {
        $RT::Logger->crit("Neither the RT var directory ($RT::VarPath) nor the system tmpdir (@{[File::Spec->tmpdir]}) are writable; falling back to in-memory parsing!");
    }

    #If someone includes a message, extract it
    $parser->extract_nested_messages(1);
    $parser->extract_uuencode(1);    ### default is false

    if ($tmpdir) {
        # If we got a writable tmpdir, write to disk
        push ( @{ $self->{'AttachmentDirs'} ||= [] }, $tmpdir );
        $parser->output_dir($tmpdir);
        $parser->filer->ignore_filename(1);

        # Set up the prefix for files with auto-generated names:
        $parser->output_prefix("part");

        # From the MIME::Parser docs:
        # "Normally, tmpfiles are created when needed during parsing, and destroyed automatically when they go out of scope"
        # Turns out that the default is to recycle tempfiles
        # Temp files should never be recycled, especially when running under perl taint checking

        $parser->tmp_recycling(0) if $parser->can('tmp_recycling');
    } else {
        # Otherwise, fall back to storing it in memory
        $parser->output_to_core(1);
        $parser->tmp_to_core(1);
        $parser->use_inner_files(1);
    }

}

=head2 ParseEmailAddress string

Returns a list of Email::Address objects
Works around the bug that Email::Address 1.889 and earlier
doesn't handle local-only email addresses (when users pass
in just usernames on the RT system in fields that expect
Email Addresses)

We don't handle the case of 
bob, fred@bestpractical.com 
because we don't want to fail parsing
bob, "Falcone, Fred" <fred@bestpractical.com>
The next release of Email::Address will have a new method
we can use that removes the bandaid

=cut

sub ParseEmailAddress {
    my $self = shift;
    my $address_string = shift;

    $address_string =~ s/^\s+|\s+$//g;

    my @addresses;
    # if it looks like a username / local only email
    if ($address_string !~ /@/ && $address_string =~ /^\w+$/) {
        my $user = RT::User->new( $RT::SystemUser );
        my ($id, $msg) = $user->Load($address_string);
        if ($id) {
            push @addresses, Email::Address->new($user->Name,$user->EmailAddress);
        } else {
            $RT::Logger->error("Unable to parse an email address from $address_string: $msg");
        }
    } else {
        @addresses = Email::Address->parse($address_string);
    }

    return @addresses;

}

=head2 RescueOutlook 

Outlook 2007/2010 have a bug when you write an email with the html format.
it will send a 'multipart/alternative' with both 'text/plain' and 'text/html'
in it.  it's cool to have a 'text/plain' part, but the problem is the part is
not so right: all the "\n" in your main message will become "\n\n" :/

this method will fix this bug, i.e. replaces "\n\n" to "\n".
return 1 if it does find the problem in the entity and get it fixed.

=cut


sub RescueOutlook {
    my $self = shift;
    my $mime = $self->Entity();
    return unless $mime;

    my $mailer = $mime->head->get('X-Mailer');
    # 12.0 is outlook 2007, 14.0 is 2010
    if ( $mailer && $mailer =~ /Microsoft(?:.*?)Outlook 1[2-4]\./ ) {
        my $text_part;
        if ( $mime->head->get('Content-Type') =~ m{multipart/mixed} ) {
            my $first = $mime->parts(0);
            if ( $first->head->get('Content-Type') =~ m{multipart/alternative} )
            {
                my $inner_first = $first->parts(0);
                if ( $inner_first->head->get('Content-Type') =~ m{text/plain} )
                {
                    $text_part = $inner_first;
                }
            }
        }
        elsif ( $mime->head->get('Content-Type') =~ m{multipart/alternative} ) {
            my $first = $mime->parts(0);
            if ( $first->head->get('Content-Type') =~ m{text/plain} ) {
                $text_part = $first;
            }
        }

        if ($text_part) {

            # use the unencoded string
            my $content = $text_part->bodyhandle->as_string;
            if ( $content =~ s/\n\n/\n/g ) {
                # only write only if we did change the content
                if ( my $io = $text_part->open("w") ) {
                    $io->print($content);
                    $io->close;
                    return 1;
                }
                else {
                    $RT::Logger->error("can't write to body");
                }
            }
        }
    }
    return;
}


sub DESTROY {
    my $self = shift;
    File::Path::rmtree([@{$self->{'AttachmentDirs'}}],0,1)
        if $self->{'AttachmentDirs'};
}



RT::Base->_ImportOverlays();

1;
