www: /$INBOX/$MSGID/d/ to diff reused Message-IDs

To ensure users aren't abusing the ability to reuse Message-IDs,
provide a convenient front-end to `lei mail-diff' from WWW.
Most of the time it's just list-appended signatures, so I expect
this to be useful for /all/ users.

1 files changed, 28 insertions, 1 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 071a2093..b8d6d85e 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -623,7 +623,8 @@ sub _msg_page_prepare {
                         return;
                 }
                 $ctx->{-html_tip} =
-"<pre>WARNING: multiple messages have this Message-ID\n</pre><pre>";
+qq[<pre>WARNING: multiple messages have this Message-ID (<a
+href="d/">diff</a>)</pre><pre>];
         } else {
                 $ctx->{first_hdr} = $eml->header_obj;
                 $ctx->{chash} = content_hash($eml) if $ctx->{smsg}; # reused MID
@@ -1225,4 +1226,30 @@ sub ghost_index_entry {
                 . '</pre>' . $end;
 }
 
+# /$INBOX/$MSGID/d/ endpoint
+sub diff_msg {
+        my ($ctx) = @_;
+        require PublicInbox::MailDiff;
+        my $ibx = $ctx->{ibx};
+        my $over = $ibx->over or return no_over_html($ctx);
+        my ($id, $prev);
+        my $md = bless { ctx => $ctx }, 'PublicInbox::MailDiff';
+        my $next_arg = $md->{next_arg} = [ $ctx->{mid}, \$id, \$prev ];
+        my $smsg = $md->{smsg} = $over->next_by_mid(@$next_arg) or
+                return; # undef == 404
+        $ctx->{-t_max} = $smsg->{ts};
+        $ctx->{-upfx} = '../../';
+        $ctx->{-apfx} = '//'; # fail on to_attr()
+        $ctx->{-linkify} = PublicInbox::Linkify->new;
+        my $mid = ascii_html($smsg->{mid});
+        $ctx->{-title_html} = "diff for duplicates of &lt;$mid&gt;";
+        PublicInbox::WwwStream::html_init($ctx);
+        print { $ctx->{zfh} } '<pre>diff for duplicates of &lt;<a href="../">',
+                                $mid, "</a>&gt;\n\n";
+        sub {
+                $ctx->attach($_[0]->([200, delete $ctx->{-res_hdr}]));
+                $md->begin_mail_diff;
+        };
+}
+
 1;