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#!/usr/bin/perl
# yttitle.pl
# When someone says something with a youtube video link in it, get the
# title and say it in the channel.
# Uses yt-dlp to do the title lookups. Works much better than the
# usual HTML-scraping, but unfortunately is *slow* (like, average 3
# sec per lookup).
# Since lookups take so long, they're done asynchronously, via
# fork(). This script owes a great debt to the dns.pl script
# included with irssi, which shows how to use irssi's pidwait and
# input_(add|remove).
no strict;
use POSIX '_exit';
use Irssi qw/
signal_add_first
pidwait_add
input_add
input_remove
/;
our $VERSION = "0.1";
our %IRSSI = (
authors => 'Urchlay',
contact => 'Urchlay on Libera',
name => 'yttitle',
description => 'get titles for youtube videos using yt-dlp',
license => 'WTFPL',
url => 'none',
);
# video ID => title
our %cache;
# keep track of video IDs of in-progress lookups, so we don't spawn
# a 2nd process for the same ID.
our %in_progress;
# TODO: the rest of these variables should be irssi settings.
# how many jobs are currently running?
our $jobcount = 0;
# attempts to spawn more simultaneous jobs than this are just ignored.
our $maxjobs = 10;
# yt-dlp processes that don't respond within this many seconds
# are terminated.
our $job_timeout = 15;
# passed to yt-dlp itself.
our $socket_timeout = 10;
# command to execute, %s replaced with video ID.
# --socket-timeout arg is seconds, should be longer that $timeout.
our $command_fmt =
"yt-dlp -q --print '%%(title)s' --socket-timeout $socket_timeout -- %s 2>/dev/null";
our $DEBUG = 1;
sub debug {
Irssi::print(join "", @_) if $DEBUG;
}
sub debugf {
Irssi::print(sprintf(@_)) if $DEBUG;
}
sub spawn_job {
my ($server, $target, $video_id) = @_;
debug("spawn_job() called, video_id $video_id");
if($jobcount > $maxjobs) {
debug("spawn_job(): jobcount $jobcount > maxjobs $maxjobs, ignoring request");
return;
}
if($in_progress{$video_id}) {
debug("spawn_job(): video_id $video_id already in queue");
return;
}
$in_progress{$video_id} = 1;
my $cmd = sprintf($command_fmt, $video_id);
debug("spawn_job() command is: $cmd");
my($read, $write);
pipe($read, $write);
my $pid = fork();
if(!defined($pid)) {
debug("spawn_job(): video_id $video_id: fork() failed!");
close $read;
close $write;
return;
}
if($pid) {
# parent
$jobcount++;
debug("spawn_job() forked, kid pid is $pid, jobcount now $jobcount");
close $write;
my $pipe_args = [ $pid, $server, $target, $video_id, $read ];
pidwait_add($pid);
$pipe_tags{$video_id} = input_add(fileno($read), INPUT_READ, \&job_done, $pipe_args);
return;
} else {
# child, debug() and Irssi::print don't work, here.
eval {
local $SIG{ALRM} = sub { die "alarum\n" };
alarm $job_timeout;
print $write `$cmd`;
alarm 0;
};
# don't bother to die() on error here, we're about to exit anyway.
if($@ && ($@ eq "alarum\n")) {
# print *something* if $cmd timed out
print $write "\n";
}
# not sure this needs to be wrapped in eval, but...
eval {
close $write;
};
_exit(1);
}
}
sub job_done {
my $pipe_args = shift;
my ($pid, $server, $target, $video_id, $read) = @$pipe_args;
debug("job_done() pid $pid, target $target, video_id $video_id, jobcount was $jobcount");
my $title = <$read>;
chomp $title;
close $read;
input_remove($pipe_tags{$video_id});
$jobcount--;
delete $in_progress{$video_id};
$cache{$video_id} = $title;
if(defined($title)) {
debug("job_done(): video_id $video_id title is $title");
} else {
debug("job_done(): video_id $video_id failed to get title");
return;
}
say_title($server, $target, $video_id, $title);
}
sub say_title {
my ($server, $target, $video_id, $title) = @_;
my $tag = "YouTube" . ($DEBUG ? "($video_id)" : "");
$server->command("msg $target $tag: $title");
}
sub on_public_msg {
my ($server, $msg, $nick, $address, $target) = @_;
my $mynick = $server->{nick};
unless(length $target) {
$target = $nick;
$nick = $mynick;
}
if($target eq $mynick) {
# private message... send response to sender
$target = $nick;
}
for my $video_id ($msg =~ /(?:youtube\.com\S+(?:embed\/|v=)|youtu.be\/)([-0-9a-zA-Z_]{11})/g) {
if($cache{$video_id}) {
debug("video_id $video_id found in cache");
say_title($server, $target, $video_id, $cache{$video_id});
} else {
debug("video_id $video_id NOT found in cache, queuing job");
spawn_job($server, $target, $video_id);
}
}
}
### main()
signal_add_first("message public", "on_public_msg");
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