#pproxy.pl setup; presumes Rocky Linux 8.6 set up as Pleroma server

#the script and nginx config changes should work as-is on any Linux
#but the commands for installing prerequisites and setting up the service
#definition are pretty RHEL/CentOS/Rocky 8-specific

#see: https://docs-develop.pleroma.social/backend/configuration/how_to_serve_another_domain_for_webfinger/
#you should first configure your Pleroma server to match that document

#IMPORTANT: you will need to replace the following two strings throughout
#this document:
#
#YOURHOST = the name your Pleroma instance is configured to think of itself as
#       i.e. "host.domain.tld"
#
#YOURDOMAIN = the name you want your instance to appear to be
#       i.e. "domain.tld"

yum install -y perl cpan

useradd pproxy
su - pproxy

cpan -Ti HTTP::Proxy

chmod u+w /home/pproxy/perl5/lib/perl5/HTTP/Proxy.pm
nano -w /home/pproxy/perl5/lib/perl5/HTTP/Proxy.pm
#CHANGE:
        host     => '127.0.0.1',
#
chmod u-w /home/pproxy/perl5/lib/perl5/HTTP/Proxy.pm

nano -w proxy.pl
#ADD:
#!/usr/bin/perl

use HTTP::Proxy qw( :log );
use HTTP::Proxy::HeaderFilter::simple;
use HTTP::Proxy::BodyFilter::simple;

my $domain = "YOURDOMAIN";
my $host = "YOURHOST";

my $proxy = HTTP::Proxy->new( port => 4001 );

my $ua = LWP::UserAgent->new(timeout => 10);
$ua->proxy(['http'], 'http://127.0.0.1:4000/');
$proxy->agent($ua);

my $bodyfilter = HTTP::Proxy::BodyFilter::simple->new(
    sub {
      my ( $self, $dataref, $message, $protocol, $buffer ) = @_;

      if(true == $message->headers->content_is_text)
      {
        ${ $_[1] } =~ s/\@${host}/\@${domain}/gi;
      }
    }
);
$proxy->push_filter(
  mime     => undef,
  response => $bodyfilter
);

$proxy->start;
#

#test run
/usr/bin/perl proxy.pl

nano -w /etc/systemd/system/pproxy.service
#ADD:
[Unit]
Description=pproxy
After=network.target

[Service]
Type=simple
User=pproxy
WorkingDirectory=/home/pproxy
ExecStart=/bin/bash -lc "/usr/bin/perl /home/pproxy/proxy.pl"
TimeoutSec=15
Restart=always

[Install]
WantedBy=multi-user.target
#

systemctl enable --now pproxy.service

service nginx stop

nano -w /etc/nginx/conf.d/pleroma.conf
#CHANGE:
upstream phoenix_direct {
    server 127.0.0.1:4000 max_fails=5 fail_timeout=60s;
}

upstream phoenix {
    server 127.0.0.1:4001 max_fails=5 fail_timeout=60s;
}
#ADD:
    location ~ ^/.well-known/webfinger {
        if ( $args ~* ^resource=acct:(.*)@YOURDOMAIN$ ) {
            set $args resource=acct:$1@YOURHOST;
        }

        proxy_pass http://phoenix;
    }

    location ~ ^/ostatus_subscribe {
        if ( $args ~* ^acct=(.*)@YOURDOMAIN$ ) {
            set $args acct=$1@YOURHOST;
        }

        proxy_pass http://phoenix;
    }

    location /static {
        proxy_pass http://phoenix_direct;
    }

    location /api/v1/accounts/update_credentials {
        proxy_pass http://phoenix_direct;
    }
#

service nginx start