+ @ret; # may be empty, this sub is called as an arg for join()
+}
+
+sub _mirror_help ($$) {
+ my ($ctx, $txt) = @_;
+ my $ibx = $ctx->{ibx};
+ my $base_url = $ibx->base_url($ctx->{env});
+ chop $base_url; # no trailing slash for "git clone"
+ my $dir = (split(m!/!, $base_url))[-1];
+ my %seen = ($base_url => 1);
+ my $top_url = $base_url;
+ $top_url =~ s!/[^/]+\z!/!;
+ $$txt .= "public-inbox mirroring instructions\n\n";
+ if ($ibx->can('cloneurl')) { # PublicInbox::Inbox
+ $$txt .=
+ "This public inbox may be cloned and mirrored by anyone:\n";
+ my @urls;
+ my $max = $ibx->max_git_epoch;
+ # TODO: some of these URLs may be too long and we may need to
+ # do something like code_footer() above, but these are local
+ # admin-defined
+ if (defined($max)) { # v2
+ for my $i (0..$max) {
+ # old epochs my be deleted:
+ -d "$ibx->{inboxdir}/git/$i.git" or next;
+ my $url = "$base_url/$i";
+ $seen{$url} = 1;
+ push @urls, "$url $dir/git/$i.git";
+ }
+ my $nr = scalar(@urls);
+ if ($nr > 1) {
+ $$txt .= "\n\t";
+ $$txt .= "# this inbox consists of $nr epochs:";
+ $urls[0] .= " # oldest";
+ $urls[-1] .= " # newest";
+ }
+ } else { # v1
+ push @urls, $base_url;
+ }
+ # FIXME: epoch splits can be different in other repositories,
+ # use the "cloneurl" file as-is for now:
+ for my $u (@{$ibx->cloneurl}) {
+ next if $seen{$u}++;
+ push @urls, $u;
+ }
+ $$txt .= "\n";
+ $$txt .= join('', map { "\tgit clone --mirror $_\n" } @urls);
+ if (my $addrs = $ibx->{address}) {
+ $addrs = join(' ', @$addrs) if ref($addrs) eq 'ARRAY';
+ my $v = defined $max ? '-V2' : '-V1';
+ $$txt .= <<EOF;
+
+ # If you have public-inbox 1.1+ installed, you may
+ # initialize and index your mirror using the following commands:
+ public-inbox-init $v $ibx->{name} $dir/ $base_url \\
+ $addrs
+ public-inbox-index $dir
+EOF
+ }
+ } else { # PublicInbox::ExtSearch
+ $$txt .= <<EOM;
+This is an external index which is an amalgamation of several public inboxes.
+Each public inbox needs to be mirrored individually.
+EOM
+ my $v = $ctx->{www}->{pi_cfg}->{lc('publicInbox.wwwListing')};
+ if (($v // '') =~ /\A(?:all|match=domain)\z/) {
+ $$txt .= <<EOM;
+A list of them is available at $top_url
+EOM
+ }
+ }
+ my $cfg_link = "$base_url/_/text/config/raw";
+ $$txt .= <<EOF;
+
+Example config snippet for mirrors: $cfg_link
+EOF
+ if ($ibx->can('imap_url')) {
+ my $imap = $ibx->imap_url($ctx);
+ if (@$imap) {
+ $$txt .= "\n";
+ $$txt .= 'IMAP subfolder(s) available under:';
+ $$txt .= "\n\t" . join("\n\t", @$imap) . "\n";
+ $$txt .= <<EOM
+ # each subfolder (starting with `0') holds 50K messages at most
+EOM
+ }
+ }
+ if ($ibx->can('nntp_url')) {
+ my $nntp = $ibx->nntp_url($ctx);
+ if (scalar @$nntp) {
+ $$txt .= "\n";
+ $$txt .= @$nntp == 1 ? 'Newsgroup' : 'Newsgroups are';
+ $$txt .= ' available over NNTP:';
+ $$txt .= "\n\t" . join("\n\t", @$nntp) . "\n";
+ }
+ }
+ if ($$txt =~ m!\b[^:]+://\w+\.onion/!) {
+ $$txt .= <<EOM
+
+note: .onion URLs require Tor: https://www.torproject.org/
+
+EOM
+ }
+ my $code_url = prurl($ctx->{env}, $PublicInbox::WwwStream::CODE_URL);
+ $$txt .= join("\n\n",
+ coderepos_raw($ctx, $top_url), # may be empty
+ "AGPL code for this site:\n\tgit clone $code_url");