+# Copyright (C) 2021 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# "lei prune-mail-sync" drops dangling sync information
+package PublicInbox::LeiPruneMailSync;
+use strict;
+use v5.10.1;
+use parent qw(PublicInbox::IPC PublicInbox::LeiInput);
+use PublicInbox::LeiExportKw;
+use PublicInbox::InboxWritable qw(eml_from_path);
+
+sub eml_match ($$) {
+ my ($eml, $oidbin) = @_;
+ $oidbin eq git_sha(length($oidbin) == 20 ? 1 : 256, $eml)->digest;
+}
+
+sub prune_mdir { # lms->each_src callback
+ my ($oidbin, $id, $self, $mdir) = @_;
+ my @try = $$id =~ /:2,[a-zA-Z]*\z/ ? qw(cur new) : qw(new cur);
+ for my $d (@try) {
+ my $src = "$mdir/$d/$$id";
+ if ($self->{verify}) {
+ my $eml = eml_from_path($src) or next;
+ return if eml_match($eml, $oidbin);
+ } elsif (-f $src) {
+ return;
+ }
+ }
+ # both tries failed
+ $self->{lei}->qerr("# maildir:$mdir $$id gone");
+ $self->{lei}->{sto}->ipc_do('lms_clear_src', "maildir:$mdir", $id);
+}
+
+sub prune_imap { # lms->each_src callback
+ my ($oidbin, $uid, $self, $uids, $url) = @_;
+ return if exists $uids->{$uid};
+ $self->{lei}->qerr("# $url $uid gone");
+ $self->{lei}->{sto}->ipc_do('lms_clear_src', $url, $uid);
+}
+
+sub input_path_url { # overrides PublicInbox::LeiInput::input_path_url
+ my ($self, $input, @args) = @_;
+ my $lms = $self->{-lms_ro} //= $self->{lse}->lms;
+ if ($input =~ /\Amaildir:(.+)/i) {
+ my $mdir = $1;
+ $lms->each_src($input, \&prune_mdir, $self, $mdir);
+ } elsif ($input =~ m!\Aimaps?://!i) {
+ my $uri = PublicInbox::URIimap->new($input);
+ my $mic = $self->{lei}->{net}->mic_for_folder($uri);
+ my $uids = $mic->search('UID 1:*');
+ $uids = +{ map { $_ => undef } @$uids };
+ $lms->each_src($$uri, \&prune_imap, $self, $uids, $$uri);
+ } else { die "BUG: $input not supported" }
+ my $wait = $self->{lei}->{sto}->ipc_do('done');
+}
+
+sub lei_prune_mail_sync {
+ my ($lei, @folders) = @_;
+ my $sto = $lei->_lei_store or return $lei->fail(<<EOM);
+lei/store uninitialized, see lei-import(1)
+EOM
+ my $lse = $sto->search;
+ my $lms = $lse->lms or return $lei->fail(<<EOM);
+lei mail_sync uninitialized, see lei-import(1)
+EOM
+ if (defined(my $all = $lei->{opt}->{all})) {
+ $lms->group2folders($lei, $all, \@folders) or return;
+ } else {
+ my $err = $lms->arg2folder($lei, \@folders);
+ $lei->qerr(@{$err->{qerr}}) if $err->{qerr};
+ return $lei->fail($err->{fail}) if $err->{fail};
+ }
+ delete $lms->{dbh};
+ $sto->write_prepare($lei);
+ my $self = bless { lse => $lse }, __PACKAGE__;
+ $lei->{opt}->{'mail-sync'} = 1; # for prepare_inputs
+ $self->prepare_inputs($lei, \@folders) or return;
+ my $j = $lei->{opt}->{jobs} || scalar(@{$self->{inputs}}) || 1;
+ undef $lms; # for fork
+ my $ops = {};
+ $sto->write_prepare($lei);
+ $lei->{auth}->op_merge($ops, $self) if $lei->{auth};
+ $self->{-wq_nr_workers} = $j // 1; # locked
+ (my $op_c, $ops) = $lei->workers_start($self, $j, $ops);
+ $lei->{wq1} = $self;
+ $lei->{-err_type} = 'non-fatal';
+ net_merge_all_done($self) unless $lei->{auth};
+ $lei->wait_wq_events($op_c, $ops); # net_merge_all_done if !{auth}
+}
+
+no warnings 'once';
+*_complete_prune_mail_sync = \&PublicInbox::LeiExportKw::_complete_export_kw;
+*ipc_atfork_child = \&PublicInbox::LeiInput::input_only_atfork_child;
+*net_merge_all = \&PublicInbox::LeiAuth::net_merge_all;
+*net_merge_all_done = \&PublicInbox::LeiInput::input_only_net_merge_all_done;
+
+1;