feat: Group and broadcast channel descriptions (#7829)

fix https://github.com/chatmail/core/issues/7766

Implementation notes:

- Descriptions are only sent with member additions, when the description
is changed, and when promoting a previously-unpromoted group, in order
not to waste bandwith.
- Descriptions are not loaded everytime a chat object is loaded, because
they are only needed for the profile. Instead, they are in their own
table, and can be loaded with their own JsonRPC call.

---------

Co-authored-by: iequidoo <117991069+iequidoo@users.noreply.github.com>

src/chat/chat_tests.rs

@@ -3156,6 +3156,119 @@ async fn test_broadcasts_name_and_avatar() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_basic() {
+    test_chat_description("", false).await.unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_unpromoted_description() {
+    test_chat_description("Unpromoted description in the beginning", false)
+        .await
+        .unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_qr() {
+    test_chat_description("", true).await.unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_unpromoted_description_qr() {
+    test_chat_description("Unpromoted description in the beginning", true)
+        .await
+        .unwrap()
+}
+
+async fn test_chat_description(initial_description: &str, join_via_qr: bool) -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let alice2 = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+
+    alice.set_config_bool(Config::SyncMsgs, true).await?;
+    alice2.set_config_bool(Config::SyncMsgs, true).await?;
+
+    tcm.section("Create a group chat, and add Bob");
+    let alice_chat_id = create_group(alice, "My Group").await?;
+
+    if !initial_description.is_empty() {
+        set_chat_description(alice, alice_chat_id, initial_description).await?;
+    }
+    sync(alice, alice2).await;
+
+    let alice2_chat_id = get_chat_id_by_grpid(
+        alice2,
+        &Chat::load_from_db(alice, alice_chat_id).await?.grpid,
+    )
+    .await?
+    .unwrap()
+    .0;
+    assert_eq!(
+        get_chat_description(alice2, alice2_chat_id).await?,
+        initial_description
+    );
+
+    let bob_chat_id = if join_via_qr {
+        let qr = get_securejoin_qr(alice, Some(alice_chat_id)).await.unwrap();
+        tcm.exec_securejoin_qr(bob, alice, &qr).await
+    } else {
+        let alice_bob_id = alice.add_or_lookup_contact_id(bob).await;
+        add_contact_to_chat(alice, alice_chat_id, alice_bob_id).await?;
+        let sent = alice.send_text(alice_chat_id, "promoting the group").await;
+        bob.recv_msg(&sent).await.chat_id
+    };
+    assert_eq!(
+        get_chat_description(bob, bob_chat_id).await?,
+        initial_description
+    );
+
+    for description in ["This is a cool group", "", "ä ẟ 😂"] {
+        tcm.section(&format!(
+            "Alice sets the chat description to '{description}'"
+        ));
+        set_chat_description(alice, alice_chat_id, description).await?;
+        let sent = alice.pop_sent_msg().await;
+        assert_eq!(
+            sent.load_from_db().await.text,
+            "You changed the chat description."
+        );
+
+        tcm.section("Bob receives the description change");
+        let rcvd = bob.recv_msg(&sent).await;
+        assert_eq!(rcvd.get_info_type(), SystemMessage::GroupDescriptionChanged);
+        assert_eq!(rcvd.text, "Chat description changed by alice@example.org.");
+
+        assert_eq!(get_chat_description(bob, rcvd.chat_id).await?, description);
+
+        tcm.section("Check Alice's second device");
+        alice2.recv_msg(&sent).await;
+        let alice2_chat_id = get_chat_id_by_grpid(
+            alice2,
+            &Chat::load_from_db(alice, alice_chat_id).await?.grpid,
+        )
+        .await?
+        .unwrap()
+        .0;
+
+        assert_eq!(
+            get_chat_description(alice2, alice2_chat_id).await?,
+            description
+        );
+    }
+
+    tcm.section("Alice calls set_chat_description() without actually changing the description");
+    set_chat_description(alice, alice_chat_id, "ä ẟ 😂").await?;
+    assert!(
+        alice
+            .pop_sent_msg_opt(Duration::from_secs(0))
+            .await
+            .is_none()
+    );
+
+    Ok(())
+}
+
 /// Tests that directly after broadcast-securejoin,
 /// the brodacast is shown correctly on both devices.
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]