searchview: support negative offsets to reverse ordering

Taking a hint from Perl array access, we'll allow negative
offsets for the 'o' parameter and to reverse the sort order.

diff --git a/lib/PublicInbox/SearchView.pm b/lib/PublicInbox/SearchView.pm
index b089de9c91412cb1e4e42a431256b97c8ebafa63..f0d803ea1583b616b6c9451aec298175b49aa8d8 100644 (file)
--- a/lib/PublicInbox/SearchView.pm
+++ b/lib/PublicInbox/SearchView.pm
@@ -34,14 +34,21 @@ sub sres_top_html {
        my $q = PublicInbox::SearchQuery->new($ctx->{qp});
        my $x = $q->{x};
        my $query = $q->{'q'};
+       my $o = $q->{o};
+       my $asc;
+       if ($o < 0) {
+               $asc = 1;
+               $o = -($o + 1); # so [-1] is the last element, like Perl lists
+       }
 
        my $code = 200;
        # double the limit for expanded views:
        my $opts = {
                limit => $q->{l},
-               offset => $q->{o},
+               offset => $o,
                mset => 1,
                relevance => $q->{r},
+               asc => $asc,
        };
        my ($mset, $total, $err, $cb);
 retry:
@@ -184,29 +191,47 @@ sub search_nav_top {
 sub search_nav_bot {
        my ($mset, $q) = @_;
        my $total = $mset->get_matches_estimated;
-       my $o = $q->{o};
        my $l = $q->{l};
-       my $end = $o + $mset->size;
-       my $beg = $o + 1;
        my $rv = '</pre><hr><pre id=t>';
+       my $o = $q->{o};
+       my $off = $o < 0 ? -($o + 1) : $o;
+       my $end = $off + $mset->size;
+       my $beg = $off + 1;
+
        if ($beg <= $end) {
                $rv .= "Results $beg-$end of $total";
                $rv .= ' (estimated)' if $end != $total;
        } else {
                $rv .= "No more results, only $total";
        }
-       my $n = $o + $l;
+       my ($next, $join, $prev);
 
-       if ($n < $total) {
-               my $qs = $q->qs_html(o => $n, l => $l);
-               $rv .= qq{  <a\nhref="?$qs"\nrel=next>next</a>}
-       }
-       if ($o > 0) {
-               $rv .= $n < $total ? '/' : '       ';
-               my $p = $o - $l;
-               my $qs = $q->qs_html(o => ($p > 0 ? $p : 0));
-               $rv .= qq{<a\nhref="?$qs"\nrel=prev>prev</a>};
+       if ($o >= 0) { # sort descending
+               my $n = $o + $l;
+               if ($n < $total) {
+                       $next = $q->qs_html(o => $n, l => $l);
+               }
+               if ($o > 0) {
+                       $join = $n < $total ? '/' : '       ';
+                       my $p = $o - $l;
+                       $prev = $q->qs_html(o => ($p > 0 ? $p : 0));
+               }
+       } else { # o < 0, sort ascending
+               my $n = $o - $l;
+
+               if (-$n < $total) {
+                       $next = $q->qs_html(o => $n, l => $l);
+               }
+               if ($o < -1) {
+                       $join = -$n < $total ? '/' : '       ';
+                       my $p = $o + $l;
+                       $prev = $q->qs_html(o => ($p < 0 ? $p : 0));
+               }
        }
+
+       $rv .= qq{  <a\nhref="?$next"\nrel=next>next</a>} if $next;
+       $rv .= $join if $join;
+       $rv .= qq{<a\nhref="?$prev"\nrel=prev>prev</a>} if $prev;
        $rv .= '</pre>';
 }
 
@@ -313,7 +338,7 @@ sub new {
        bless {
                q => $qp->{'q'},
                x => $qp->{x} || '',
-               o => (($qp->{o} || '0') =~ /([0-9]+)/),
+               o => (($qp->{o} || '0') =~ /(-?[0-9]+)/),
                l => $l,
                r => (defined $r && $r ne '0'),
        }, $class;