#!/usr/bin/perl
use warnings;
use strict;
use autodie;
use Data::Dumper;
use Email::Sender::Transport::SMTP::Persistent;
use Email::Stuffer;
use Encode;
use Encode::Locale;
use Encode::MIME::Header;
use Getopt::Long;
use List::Util;
use MCE;
use MCE::Loop;
use MCE::Flow;
use MCE::Shared;
use Path::Tiny;
use Pod::Usage;
use Time::HiRes qw(gettimeofday tv_interval);

# apt install cpanminus libemail-sender-perl libmce-perl libemail-stuffer-perl libpath-tiny-perl
# cpanm MCE::Shared

use open ':encoding(locale)';
@ARGV = map { decode(locale => $_, 1) } @ARGV;

# ####
# configurable settings
# ####

my $transport = Email::Sender::Transport::SMTP::Persistent->new({
	host => 'localhost',
	port => 25,
	#debug => 1,
});
my $thread_count = 64;
my $chunksize = 1;

# ####
# end config
# ####

=head1 NAME

mailer.pl - send lots of mails

=head1 SYNOPSIS

mailer.pl options ...

 Options:
    --help, -h               short help message
    --to <email or file>     recipient(s)
    --from <email>           from
    --subject <string>       subject
    --content-html <file>    body of the mail (html part) (optional)
    --content-txt <file>     body of the mail (text part)
    --debug                  output extra debug information

=cut

my %opts = ();

Getopt::Long::Configure ("bundling");
pod2usage(-verbose => 0) if (@ARGV== 0);
GetOptions(\%opts, "help|h", "to=s", "from=s", "subject=s", "content-html=s", "content-txt=s", "debug") or pod2usage(2);
pod2usage(0) if $opts{help};

sub trim {
	my $string = shift;
	$string =~ s/^\s+//;
	$string =~ s/\s+$//;
	return $string;
}

my $subject = $opts{subject};
my $from = $opts{from};
my $content_html;
my $content_txt;

die "Error: subject not set\n" unless ($opts{subject});
die "Error: from not set\n" unless ($opts{from});
die "Error: content-txt not set\n" unless ($opts{"content-txt"});
die "Error: can't read content-txt: $!\n" unless (-r $opts{"content-txt"});
die "Error: can't read content-html: $!\n" if ($opts{"content-html"} and not -r $opts{"content-html"});

if ($opts{"content-html"}) {
	$content_html = path($opts{"content-html"})->slurp_utf8;
}
$content_txt = path($opts{"content-txt"})->slurp_utf8;

print "Building email ... " if $opts{debug};

# create mail
# To will be filled when sending
my $msg = Email::Stuffer->new();
$msg->from($from);
$msg->subject(trim($subject));
$msg->text_body($content_txt);
$msg->html_body($content_html);
$msg->header("Precedence", "bulk");
#$msg->header("List-Unsubscribe", "<mailto:$from>");
$msg->transport($transport);

print "done\n" if $opts{debug};

print "creating workers\n" if $opts{debug};

print "Sending\n";

my $send_time = [gettimeofday];
my $queue = MCE::Shared->queue(await => 1, fast => 1);

mce_flow {
	task_name => ['producer', 'sender'],
	max_workers => [1, $thread_count]},
sub {
	if ($opts{to} =~ m/.+\@.+\..+/) {
		$queue->enqueue($opts{to});
	} else {
		if (-r $opts{to}) {
			open my $fh, "<", $opts{to};
			while (<$fh>) {
				$queue->enqueue($_);
				$queue->await($thread_count);
			}
			close $fh;
		} else {
			print STDERR "Error: can't read recipient file: $!\n";
		}
	}
	$queue->end();
},
sub {
	while (defined (my $to = $queue->dequeue())) {
		$msg->to($to);
		$msg->send();
		print "sent mail in worker ".MCE->wid."\n" if $opts{debug};
	}
	$transport->disconnect;
};

print "done after ".tv_interval($send_time)." seconds\n";