view: per-message view links to real previous sibling

This is closer to the behavior of thread-aware MUAs.

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index f47ecba0ae27b8eb364f5842ea113774a32f78aa..054b358003b95edf1c77e49f0004a46d80b1740e 100644 (file)
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -636,21 +636,35 @@ sub html_footer {
        if ($idx && $srch) {
                $idx .= "\n";
                thread_skel(\$idx, $ctx, $hdr, $tpfx);
-               my $p = $ctx->{parent_msg};
-               my $next = $ctx->{next_msg};
-               if ($p) {
-                       $p = PublicInbox::Hval->new_msgid($p);
-                       $p = $p->as_href;
-                       $irt = "<a\nhref=\"$upfx$p/\"\nrel=prev>parent</a> ";
-               } else {
-                       $irt = ' ' x length('parent ');
+               my ($next, $prev);
+               my $parent = '       ';
+               $next = $prev = '    ';
+
+               if (my $n = $ctx->{next_msg}) {
+                       $n = PublicInbox::Hval->new_msgid($n)->as_href;
+                       $next = "<a\nhref=\"$upfx$n/\"\nrel=next>next</a>";
                }
-               if ($next) {
-                       my $n = PublicInbox::Hval->new_msgid($next)->as_href;
-                       $irt .= "<a\nhref=\"$upfx$n/\"\nrel=next>next</a> ";
-               } else {
-                       $irt .= ' ' x length('next ');
+               my $u;
+               my $par = $ctx->{parent_msg};
+               if ($par) {
+                       $u = PublicInbox::Hval->new_msgid($par)->as_href;
+                       $u = "$upfx$u/";
                }
+               if (my $p = $ctx->{prev_msg}) {
+                       $prev = PublicInbox::Hval->new_msgid($p)->as_href;
+                       if ($p && $par && $p eq $par) {
+                               $prev = "<a\nhref=\"$upfx$prev/\"\n" .
+                                       'rel=prev>prev parent</a>';
+                               $parent = '';
+                       } else {
+                               $prev = "<a\nhref=\"$upfx$prev/\"\n" .
+                                       'rel=prev>prev</a>';
+                               $parent = " <a\nhref=\"$u\">parent</a>" if $u;
+                       }
+               } elsif ($u) { # unlikely
+                       $parent = " <a\nhref=\"$u\"\nrel=prev>parent</a>";
+               }
+               $irt = "$next $prev$parent ";
        } else {
                $irt = '';
        }
@@ -744,6 +758,8 @@ sub _skel_header {
                        $$dst .= "<b>$d<a\nid=r\nhref=\"#t\">".
                                 "$attr [this message]</a></b>\n";
                        return;
+               } else {
+                       $ctx->{prev_msg} = $mid;
                }
        } else {
                $ctx->{next_msg} ||= $mid;