1 files changed, 56 insertions, 0 deletions

diff --git a/lib/PublicInbox/ExtSearch.pm b/lib/PublicInbox/ExtSearch.pm
index dd93cd32..20ec3224 100644
--- a/lib/PublicInbox/ExtSearch.pm
+++ b/lib/PublicInbox/ExtSearch.pm
@@ -11,6 +11,7 @@ use PublicInbox::Over;
 use PublicInbox::Inbox;
 use File::Spec ();
 use PublicInbox::MiscSearch;
+use DBI qw(:sql_types); # SQL_BLOB
 
 # for ->reopen, ->mset, ->mset_to_artnums
 use parent qw(PublicInbox::Search);
@@ -49,6 +50,61 @@ sub git {
         $self->{git} //= PublicInbox::Git->new("$self->{topdir}/ALL.git");
 }
 
+# returns an arrayref of [ $NEWSGROUP_NAME:$ART_NO ] using
+# the `xref3' table
+sub nntp_xref_for { # NNTP only
+        my ($self, $xibx, $xsmsg) = @_;
+        my $dbh = over($self)->dbh;
+
+        my $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT ibx_id FROM inboxes WHERE eidx_key = ? LIMIT 1
+
+        $sth->execute($xibx->{newsgroup});
+        my $xibx_id = $sth->fetchrow_array // do {
+                warn "W: `$xibx->{newsgroup}' not found in $self->{topdir}\n";
+                return;
+        };
+
+        $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT docid FROM xref3 WHERE oidbin = ? AND xnum = ? AND ibx_id = ? LIMIT 1
+
+        $sth->bind_param(1, pack('H*', $xsmsg->{blob}), SQL_BLOB);
+        $sth->bind_param(2, $xsmsg->{num});
+        $sth->bind_param(3, $xibx_id);
+        $sth->execute;
+        my $docid = $sth->fetchrow_array // do {
+                warn <<EOF;
+W: `$xibx->{newsgroup}:$xsmsg->{num}' not found in $self->{topdir}"
+EOF
+                return;
+        };
+
+        # LIMIT is number of newsgroups on server:
+        $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT ibx_id,xnum FROM xref3 WHERE docid = ?
+
+        $sth->execute($docid);
+        my $rows = $sth->fetchall_arrayref;
+
+        my $eidx_key_sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT eidx_key FROM inboxes WHERE ibx_id = ? LIMIT 1
+
+        my %xref = map {
+                my ($ibx_id, $xnum) = @$_;
+                if ($ibx_id == $xibx_id) {
+                        ();
+                } else {
+                        $eidx_key_sth->execute($ibx_id);
+                        my $eidx_key = $eidx_key_sth->fetchrow_array;
+
+                        # only include if there's a newsgroup name
+                        $eidx_key && index($eidx_key, '/') >= 0 ?
+                                () : ($eidx_key => $xnum)
+                }
+        } @$rows;
+        [ map { "$_:$xref{$_}" } sort keys %xref ]; # match NNTP LIST order
+}
+
 sub mm { undef }
 
 sub altid_map { {} }