www: support $MESSAGE_ID/R/ endpoint for replies

Setting the "In-Reply-To:" header via mailto: links is not
well-supported and should probably not be encouraged unless
the client situation improves.

So instead, teach users more widely-supported ways of setting
the In-Reply-To: header to ensure proper threading of replies.

1 files changed, 16 insertions, 2 deletions

diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index 77910f67..1f28df20 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -21,7 +21,7 @@ require PublicInbox::Git;
 use PublicInbox::GitHTTPBackend;
 our $LISTNAME_RE = qr!\A/([\w\.\-]+)!;
 our $MID_RE = qr!([^/]+)!;
-our $END_RE = qr!(f/|T/|t/|t\.mbox(?:\.gz)?|t\.atom|raw|)!;
+our $END_RE = qr!(f/|T/|t/|R/|t\.mbox(?:\.gz)?|t\.atom|raw|)!;
 our $pi_config;
 
 sub run {
@@ -58,7 +58,7 @@ sub run {
                 msg_page($ctx, $1, $2, $3);
 
         # in case people leave off the trailing slash:
-        } elsif ($path_info =~ m!$LISTNAME_RE/$MID_RE/(f|T|t)\z!o) {
+        } elsif ($path_info =~ m!$LISTNAME_RE/$MID_RE/(f|T|t|R)\z!o) {
                 my ($listname, $mid, $suffix) = ($1, $2, $3);
                 $suffix .= $suffix =~ /\A[tT]\z/ ? '/#u' : '/';
                 r301($ctx, $listname, $mid, $suffix);
@@ -200,6 +200,19 @@ sub get_full_html {
           [ PublicInbox::View::msg_html($ctx, $mime, undef, $foot)] ];
 }
 
+# /$LISTNAME/$MESSAGE_ID/R/                   -> HTML content (fullquotes)
+sub get_reply_html {
+        my ($ctx) = @_;
+        my $x = mid2blob($ctx) or return r404($ctx);
+
+        require PublicInbox::View;
+        my $foot = footer($ctx);
+        require Email::MIME;
+        my $hdr = Email::MIME->new($x)->header_obj;
+        [ 200, [ 'Content-Type' => 'text/html; charset=UTF-8' ],
+          [ PublicInbox::View::msg_reply($ctx, $hdr, $foot)] ];
+}
+
 # /$LISTNAME/$MESSAGE_ID/t/
 sub get_thread {
         my ($ctx, $flat) = @_;
@@ -407,6 +420,7 @@ sub msg_page {
                 'T/' eq $e and return get_thread($ctx, 1);
                 'raw' eq $e and return get_mid_txt($ctx);
                 'f/' eq $e and return get_full_html($ctx);
+                'R/' eq $e and return get_reply_html($ctx);
         }
         r404($ctx);
 }