smarter mailinglist's square bracket prefixes (#3452)

some mailinglists have their name in square brackets prepended to the subject.

we pick up that name and remove the square brackets,
as these do not look good as the chat name in delta chat.

if a mailing list has a sequence of square brackets, we use all of them
(this seems to be okayish, at least i do not know of any complains).

however, the removal of square brackets was not nice for sequences,
resulting in `ml topic] [sub topic`.

this pr removes the square brackets only for the first name
and leave the other ones as is.

CHANGELOG.md

@@ -6,6 +6,7 @@
 - switch from `async-std` to `tokio` as the async runtime #3449
 
 ### Fixes
+- mailing list: remove square-brackets only for first name #3452
 
 
 ## 1.87.0

src/dc_receive_imf.rs

@@ -1739,13 +1739,14 @@ async fn create_or_lookup_mailinglist(
         }
     }
 
-    // if we have an additional name square brackets in the subject, we prefer that
+    // additional names in square brackets in the subject are preferred
     // (as that part is much more visible, we assume, that names is shorter and comes more to the point,
     // than the sometimes longer part from ListId)
     let subject = mime_parser.get_subject().unwrap_or_default();
-    static SUBJECT: Lazy<Regex> = Lazy::new(|| Regex::new(r"^.{0,5}\[(.*.)\]").unwrap());
+    static SUBJECT: Lazy<Regex> =
+        Lazy::new(|| Regex::new(r"^.{0,5}\[(.+?)\](\s*\[.+\])?").unwrap()); // remove square brackets around first name
     if let Some(cap) = SUBJECT.captures(&subject) {
-        name = cap[1].to_string();
+        name = cap[1].to_string() + cap.get(2).map_or("", |m| m.as_str());
     }
 
     // if we do not have a name yet and `From` indicates, that this is a notification list,
@@ -3165,6 +3166,31 @@ Hello mailinglist!\r\n"
         assert!(chat.can_send(&t.ctx).await.unwrap());
     }
 
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_mailing_list_multiple_names_in_subject() -> Result<()> {
+        let t = TestContext::new_alice().await;
+        t.set_config(Config::ShowEmails, Some("2")).await?;
+        dc_receive_imf(
+            &t,
+            b"From: Foo Bar <foo@bar.org>\n\
+    To: deltachat/deltachat-core-rust <deltachat-core-rust@noreply.github.com>\n\
+    Subject: [ola list] [foo][bar]  just a subject\n\
+    Message-ID: <3333@example.org>\n\
+    List-ID: \"looong description of 'ola list', with foo, bar\" <delta.codespeak.net>\n\
+    Date: Sun, 22 Mar 2020 22:37:57 +0000\n\
+    \n\
+    hello\n",
+            false,
+        )
+        .await
+        .unwrap();
+        let msg = t.get_last_msg().await;
+        let chat_id = msg.get_chat_id();
+        let chat = Chat::load_from_db(&t, chat_id).await?;
+        assert_eq!(chat.name, "ola list [foo][bar]");
+        Ok(())
+    }
+
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_majordomo_mailing_list() {
         let t = TestContext::new_alice().await;