#!/usr/bin/perl

# Written by Manuel Arriaga. You may do whatever you wish with this code.

# Required modules:

use Mail::POP3Client;
use Mail::Sender;
use Mail::MboxParser::Mail;
use Archive::Zip qw( :ERROR_CODES :CONSTANTS);


##################
# CONFIGURATION: #
##################

# Account to which the zipped archive of all attachments will be sent (note: this CAN be the same account from which attachments are retrieved)::

$user_email = 'joe@example.net';

# POP3 account from which we will retrieve the files:

$username = 'joe';
$password = 'secret';
$server = 'pop.example.net';

# SMTP server to use when mailing the zip archive to $user_email:

$smtp_host = 'smtp.example.net';

# Set the following variables to non-empty strings if you wish to send a short acknowledgement email to all those who sent you an attachment which was successfully downloaded:

$ack_from = 'Joe User <joe@example.net>'; # what goes in the 'From: ' field of the acknowledgements

$ack_to = 'Students'; # String which will replace the list of all ack. email recipients
  
$ack_msg = 'I received your paper!'; # acknowledgement message

$ack_subject = 'Confirming reception of paper'; # subject of confirmation email(s)
  

########################
# END OF CONFIGURATION #
########################

###########
# SCRIPT: #
###########


#######################
# ====> SUB-ROUTINES: #
#######################
  

sub zip()
  {
      my $zip_file = $attachments_dir . '.zip';
      
      $zip = Archive::Zip->new();
      $zip->addTree($attachments_dir);
      
      if ($zip->writeToFileNamed($zip_file) != AZ_OK)
      {return undef;}
      else
      {return $zip_file;}
  }

   
sub email_zip()
  {
      my $sender = new Mail::Sender{smtp => $smtp_host, from => 'getattached.perl\@$smtp_host'};
      
      $sender->MailFile({to => $user_email,
			    subject => 'Attachments retrieved by getattached.perl',
			    msg => "Attached to this email you will find a zip archive containing the $number_attachments files you were sent in emails with \"$identifier\" in the subject line.",
			    file => $zip_file});
      
      if ($sender->Error)
      {print "\n\nCouldn't send email: $Mail::Sender::Error. The messages have been removed from the server; all the attachments can be found in $zip_file.\n\n";}
      else
      {print "\n\nZipped archive $zip_file successfully sent!!\n\n";}
      
      return 1;   
  }

sub email_ack()
  {
      my $sender = new Mail::Sender{smtp => $smtp_host, 
	    from => $ack_from,
	    to => \@sender_emails,
	    fake_to => $ack_to,
	    subject => $ack_subject};
      
      $sender->MailMsg({msg => $ack_msg});
      
      if ($sender->Error)
      {print "Couldn't send acknowledgement emails: $Mail::Sender::Error.\n\n";}
      else
      {print "Acknowledgement emails successfully sent!\n\n";}
      
      return 1;   
  }


sub move_files_to_attach_dir()
{
    opendir TMPDIR, $tmp_dir or return undef;

    @orig_files = readdir TMPDIR;
    shift @orig_files; shift @orig_files; # remove '.' and '..'
    
    foreach $file (@orig_files)
    {
	$orig_file = $tmp_dir . '/' . $file;
	$dest_file = $attachments_dir . '/' . $file;
	
	while (-e $dest_file)
	{
	    if (($base, $version, $ext) = ($dest_file =~ /(.+)\[(\d+)\]\.(.+)/))
	    {
		$dest_file = $base . '[' . ++$version . ']' . '.' . $ext;
	    }
	    else
	    {
		$dest_file =~ s/(.+)\.(.+)/$1\[2\]\.$2/;
	    }
	}

	rename $orig_file, $dest_file or return undef;
    }
    
    return 1;
}


###################
# ====> "MAIN()": #
###################


# Read the identifier from the command line:

die "Usage: getattached.perl identifier\n\nwhere identifier is the string to be found in email subject lines.\n\n" 
  unless $identifier = $ARGV[0];


# Prepare the dir which will hold the attachments and after which the zip file will be named:

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
  localtime(time);

$year += 1900;

$attachments_dir = $identifier . "_$year-$mon-$mday\_$hour:$min:$sec";

mkdir $attachments_dir or die "\nCouldn't create directory $attachments_dir.\n\n";

$tmp_dir = '.getattached-temp';


# Connect to POP server:

 $pop = new Mail::POP3Client ( 
     USER       => $username,
     PASSWORD   => $password,
     HOST       => $server,
     PORT       => 110,
 );

$number_emails = $pop->Count();

print "\nThe account contains $number_emails messages.\n";


# Iterate along the mail box looking for messages matching the identifier and containing attachments:

$number_attachments = 0;

$error = "false";

@sender_emails;

for( $i = 1; $i <= $number_emails; $i++ ) {
    
    print "\nLooking at message $i: ";

    @header  = $pop->Head($i);

    @body    = $pop->Body($i);
    

    $mail = new Mail::MboxParser::Mail(\@header, \@body);
    
    $subject = $mail->header->{subject};
    
    unless (lc($subject) eq lc($identifier))
    {
	print "skipping because the subject line ($subject) doesn't match the identifier.\n";
	next;
    }
    
    print "matches the identifier ";
    
    @attachs = $mail->store_all_attachments(path => $tmp_dir);
    
    if (! move_files_to_attach_dir())
    {
	$error = "true"; 
	last;
    }
    
    if (@attachs)
    {
	print "and has attachment(s): @attachs.\n";
	
	$number_attachments += @attachs;
	
	push @sender_emails, $mail->from()->{email};
	
	$pop->Delete($i);
    }
    else
    { print "but it doesn't have attachments.\n";}
}


# Check the error flag and the number of retrieved attachments:

if ($error eq "true" ||  # An error occurred in the message loop above
    ($number_attachments > 0 && ! ($zip_file = zip())))  # No error happened above but attachments exist and zipping them failed
{
    $pop->Reset();
    
    print "\n\nAn error occurred; all messages were left on the server.\n\n";
}
elsif ($number_attachments > 0) # No errors occurred, attachments exist and we now have a zip file called $zip_file:
{
    print "\n\n$number_attachments attachments have been zipped, emailing the archive $zip_file to $user_email...\n";

    email_zip();  # Even if email_zip() failed, we *remove* the messages from the server and acknowledge receipt because a handy zip file is already available to the user
    
    email_ack() if ($ack_msg && $ack_subject);
    
}
else # No attachments were downloaded
  {
      print "\n\nNo attachments were downloaded, leaving...\n\n";
  }

system "rm", "-rf", "$attachments_dir"; # try to clean up before leaving (we keep the zip file around in case the email gets 'lost')

$pop->Close();

exit;