#!/usr/bin/perl -w
# Copyright (C) 2014-2021 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
#
# Used for training spam (via SpamAssassin) and removing messages from a
# public-inbox
my $help = <<EOF;
usage: public-inbox-learn [OPTIONS] [spam|ham|rm] </path/to/RFC2822_message

required action argument:

   spam  unindex the message and train as spam
     rm  remove the message without training as spam
    ham  index the message (based on To:/Cc: headers) and train as ham

options:

  --all  scan all inboxes on `rm'

See public-inbox-learn(1) man page for full documentation.
EOF
use strict;
use PublicInbox::Config;
use PublicInbox::InboxWritable;
use PublicInbox::Eml;
use PublicInbox::Address;
use PublicInbox::Spamcheck::Spamc;
use Getopt::Long qw(:config gnu_getopt no_ignore_case auto_abbrev);
my %opt = (all => 0);
GetOptions(\%opt, qw(all help|h)) or die $help;
use PublicInbox::Import;

my $train = shift or die $help;
if ($train !~ /\A(?:ham|spam|rm)\z/) {
	die "`$train' not recognized.\n$help";
}
die "--all only works with `rm'\n" if $opt{all} && $train ne 'rm';

my $spamc = PublicInbox::Spamcheck::Spamc->new;
my $pi_cfg = PublicInbox::Config->new;
local $PublicInbox::Import::DROP_UNIQUE_UNSUB;
PublicInbox::Import::load_config($pi_cfg);
my $err;
my $mime = PublicInbox::Eml->new(do{
	my $data = PublicInbox::IO::read_all \*STDIN;
	PublicInbox::Eml::strip_from($data);

	if ($train ne 'rm') {
		eval {
			if ($train eq 'ham') {
				$spamc->hamlearn(\$data);
			} elsif ($train eq 'spam') {
				$spamc->spamlearn(\$data);
			}
			die "spamc failed with: $?\n" if $?;
		};
		$err = $@;
	}
	\$data
});

sub remove_or_add ($$$$) {
	my ($ibx, $train, $mime, $addr) = @_;

	# We do not touch GIT_COMMITTER_* env here so we can track
	# who trained the message.
	$ibx->{name} = $ENV{GIT_COMMITTER_NAME} // $ibx->{name};
	$ibx->{-primary_address} = $ENV{GIT_COMMITTER_EMAIL} // $addr;
	$ibx = PublicInbox::InboxWritable->new($ibx);
	$ibx->{indexlevel} = $ibx->detect_indexlevel;
	my $im = $ibx->importer(0);

	if ($train eq "rm") {
		# This needs to be idempotent, as my inotify trainer
		# may train for each cross-posted message, and this
		# script already learns for every list in
		# ~/.public-inbox/config
		$im->remove($mime, $train);
	} elsif ($train eq "ham") {
		# no checking for spam here, we assume the message has
		# been reviewed by a human at this point:
		PublicInbox::MDA->set_list_headers($mime, $ibx);

		# Ham messages are trained when they're marked into
		# a SEEN state, so this is idempotent:
		$im->add($mime);
	}
	$im->done;
}

# spam is removed from all known inboxes since it is often Bcc:-ed
if ($train eq 'spam' || ($train eq 'rm' && $opt{all})) {
	$pi_cfg->each_inbox(sub {
		my ($ibx) = @_;
		$ibx = PublicInbox::InboxWritable->new($ibx);
		my $im = $ibx->importer(0);
		$im->remove($mime, $train);
		$im->done;
	});
} else {
	require PublicInbox::MDA;

	# get all recipients
	my %dests; # address => <PublicInbox::Inbox|0(false)>
	for ($mime->header('Cc'), $mime->header('To')) {
		foreach my $addr (PublicInbox::Address::emails($_)) {
			$addr = lc($addr);
			$dests{$addr} //= $pi_cfg->lookup($addr) // 0;
		}
	}

	# n.b. message may be cross-posted to multiple public-inboxes
	my %seen;
	while (my ($addr, $ibx) = each %dests) {
		next unless ref($ibx); # $ibx may be 0
		next if $seen{0 + $ibx}++;
		remove_or_add($ibx, $train, $mime, $addr);
	}
	my $dests = PublicInbox::MDA->inboxes_for_list_id($pi_cfg, $mime);
	for my $ibx (@$dests) {
		next if $seen{0 + $ibx}++;
		remove_or_add($ibx, $train, $mime, $ibx->{-primary_address});
	}
}

if ($err) {
	warn $err;
	exit 1;
}