view: thread using <ul> instead of <table>

On second viewing, this does render small cues which makes the
output more pleasant for lynx users.  We avoid injecting the
root (level=0) message into a list since it still wastes
precious horizontal whitespace on small displays.

This also results in small reductions in bandwidth usage as
it takes fewer tags/whitespace to render unordered lists.

1 files changed, 34 insertions, 18 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index ad90eb3d..bcd2ebc4 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -103,11 +103,7 @@ sub index_entry {
         }
 
         my $ts = _msg_date($mime);
-        my $rv = "<table\nsummary=l$level><tr>";
-        if ($level) {
-                $rv .= '<td><pre>' . (INDENT x $level) . '</pre></td>';
-        }
-        $rv .= "<td\nid=s$midx><pre>";
+        my $rv = "<pre\nid=s$midx>";
         $rv .= "<b\nid=$id>$subj</b>\n";
         $rv .= "- $from @ $ts UTC - ";
         $rv .= "<a\nhref=\"#s$next\">next</a>";
@@ -155,8 +151,7 @@ sub index_entry {
                                 "<a\nhref=\"${path}$href/T/#u\">flat</a>]";
                 }
         }
-
-        $fh->write($rv .= '</pre></td></tr></table>');
+        $fh->write($rv .= '</pre>');
 }
 
 sub thread_html {
@@ -181,6 +176,7 @@ sub emit_thread_html {
                 seen => $seen,
                 root_anchor => anchor_for($mid),
                 anchor_idx => 0,
+                max_level => 0,
         };
 
         require PublicInbox::Git;
@@ -191,6 +187,10 @@ sub emit_thread_html {
         } else {
                 my $th = thread_results($msgs);
                 thread_entry(\$cb, $git, $state, $_, 0) for $th->rootset;
+                if (my $max = $state->{max_level}) {
+                        my $x = $max > 1 ? ('</ul></li>' x ($max-1)) : '';
+                        $cb->write($x . '</ul>');
+                }
         }
         $git = undef;
         Email::Address->purge_cache;
@@ -637,12 +637,25 @@ sub ghost_parent {
         qq{[parent not found: &lt;<a\nhref="$upfx$href/">$html</a>&gt;]};
 }
 
-sub ghost_table {
-        my ($upfx, $mid, $level) = @_;
-        "<table\nsummary=ghost><tr><td>" .
-                (INDENT x $level) . '</td><td><pre>' .
-                ghost_parent($upfx, $mid) .
-                '</pre></td></table>';
+sub __thread_adj_level {
+        my ($cb, $state, $level) = @_;
+
+        return if $level <= 0; # flat output
+        my $max = $state->{max_level};
+        if ($level > $max) {
+                $state->{max_level} = $level;
+                $$cb->write(($max ? '<li>' : ''). '<ul><li>');
+        } else {
+                $$cb->write('<li>');
+        }
+}
+
+sub __ghost_flush {
+        my ($cb, $state, $upfx, $mid, $level) = @_;
+
+        __thread_adj_level($cb, $state, $level);
+        $$cb->write('<pre>'. ghost_parent($upfx, $mid) .  '</pre>' .
+                        ($level > 0 ? '</li>' : ''));
 }
 
 sub __thread_entry {
@@ -655,20 +668,23 @@ sub __thread_entry {
         } or return;
 
         if ($state->{anchor_idx} == 0) {
-                thread_html_head($cb, $mime, $state);
+                thread_html_head($cb, $mime, $state, $level);
         }
 
         if (my $ghost = delete $state->{ghost}) {
                 # n.b. ghost messages may only be parents, not children
                 foreach my $g (@$ghost) {
-                        $$cb->write(ghost_table('../../', @$g));
+                        __ghost_flush($cb, $state, '../../', @$g);
                 }
         }
+        __thread_adj_level($cb, $state, $level);
         index_entry($$cb, $mime, $level, $state);
+        $$cb->write('</li>') if $level > 0;
+
         1;
 }
 
-sub __ghost_entry {
+sub __ghost_prepare {
         my ($state, $node, $level) = @_;
         my $ghost = $state->{ghost} ||= [];
         push @$ghost, [ $node->messageid, $level ];
@@ -679,10 +695,10 @@ sub thread_entry {
         return unless $node;
         if (my $mime = $node->message) {
                 unless (__thread_entry($cb, $git, $state, $mime, $level)) {
-                        __ghost_entry($state, $node, $level);
+                        __ghost_prepare($state, $node, $level);
                 }
         } else {
-                __ghost_entry($state, $node, $level);
+                __ghost_prepare($state, $node, $level);
         }
 
         thread_entry($cb, $git, $state, $node->child, $level + 1);