lei_store: local storage for Local Email Interface

Still unstable, this builds off the equally unstable extindex :P

This will be used for caching/memoization of traditional mail
stores (IMAP, Maildir, etc) while providing indexing via Xapian,
along with compression, and checksumming from git.

Most notably, this adds the ability to add/remove per-message
keywords (draft, seen, flagged, answered) as described in the
JMAP specification (RFC 8621 section 4.1.1).

We'll use `.' (a single period) as an $eidx_key since it's an
invalid {inboxdir} or {newsgroup} name.

1 files changed, 40 insertions, 0 deletions

diff --git a/lib/PublicInbox/LeiSearch.pm b/lib/PublicInbox/LeiSearch.pm
new file mode 100644
index 00000000..9cfd6ea2
--- /dev/null
+++ b/lib/PublicInbox/LeiSearch.pm
@@ -0,0 +1,40 @@
+# Copyright (C) 2020 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+package PublicInbox::LeiSearch;
+use strict;
+use v5.10.1;
+use parent qw(PublicInbox::ExtSearch);
+use PublicInbox::Search;
+
+sub combined_docid ($$) {
+        my ($self, $num) = @_;
+        my $nshard = ($self->{nshard} // 1);
+        ($num - 1) * $nshard  + 1;
+}
+
+sub msg_keywords {
+        my ($self, $num) = @_; # num_or_mitem
+        my $xdb = $self->xdb; # set {nshard};
+        my $docid = ref($num) ? $num->get_docid : do {
+                # get combined docid from over.num:
+                # (not generic Xapian, only works with our sharding scheme)
+                my $nshard = $self->{nshard} // 1;
+                ($num - 1) * $nshard + $num % $nshard + 1;
+        };
+        my %kw;
+        eval {
+                my $end = $xdb->termlist_end($docid);
+                my $cur = $xdb->termlist_begin($docid);
+                for (; $cur != $end; $cur++) {
+                        $cur->skip_to('K');
+                        last if $cur == $end;
+                        my $kw = $cur->get_termname;
+                        $kw =~ s/\AK//s and $kw{$kw} = undef;
+                }
+        };
+        warn "E: #$docid ($num): $@\n" if $@;
+        wantarray ? sort(keys(%kw)) : \%kw;
+}
+
+1;