feat: Stock string for joining a channel (#7480)

Add a stock string `%1$s invited you to join this channel.\n\nWaiting
for the device of %2$s to reply…`, which is shown when a user starts to
join a channel.

I did _not_ add an equivalent to `%1$s replied, waiting for being added
to the group…`, which is shown when vg-auth-required was received. I
don't think that this would add any information that's interesting to
the user, other than 'something is happening, hang on'. And the more
text on the screen, the less likely that anyone reads it. But if others
think differently, we can also add it.

With this PR, joining a channel looks like this:

```
Msg#2003: info (Contact#Contact#Info): Messages are end-to-end encrypted. [NOTICED][INFO]
Msg#2004: info (Contact#Contact#Info): Alice invited you to join this channel.

Waiting for the device of Alice to reply… [NOTICED][INFO]
Msg#2007🔒:  (Contact#Contact#2001): You joined the channel. [FRESH][INFO]
```

deltachat-ffi/deltachat.h

@@ -7756,7 +7756,17 @@ void dc_event_unref(dc_event_t* event);
 /// Subtitle for channel join qrcode svg image generated by the core.
 ///
 /// `%1$s` will be replaced with the channel name.
-#define DC_STR_SECURE_JOIN_CHANNEL_QR_DESC  201
+#define DC_STR_SECURE_JOIN_CHANNEL_QR_DESC 201
+
+/// "You joined the channel."
+#define DC_STR_MSG_YOU_JOINED_CHANNEL 202
+
+/// "%1$s invited you to join this channel. Waiting for the device of %2$s to reply…"
+///
+/// Added as an info-message directly after scanning a QR code for joining a broadcast channel.
+///
+/// `%1$s` and `%2$s` will both be replaced by the name of the inviter.
+#define DC_STR_SECURE_JOIN_CHANNEL_STARTED 203
 
 /// "Proxy Enabled"
 ///

deltachat-rpc-client/tests/test_securejoin.py

@@ -164,7 +164,7 @@ def test_qr_securejoin_broadcast(acfactory, all_devices_online):
 
         if please_wait_info_msg:
             first_msg = chat_msgs.pop(0).get_snapshot()
-            assert first_msg.text == "Establishing connection, please wait…"
+            assert "invited you to join this channel" in first_msg.text
             assert first_msg.is_info
 
         member_added_msg = chat_msgs.pop(0).get_snapshot()

deltachat-rpc-client/tests/test_something.py

@@ -874,7 +874,7 @@ def test_leave_broadcast(acfactory, all_devices_online):
 
         if please_wait_info_msg:
             first_msg = chat_msgs.pop(0).get_snapshot()
-            assert first_msg.text == "Establishing connection, please wait…"
+            assert "invited you to join this channel" in first_msg.text
             assert first_msg.is_info
 
         member_added_msg = chat_msgs.pop(0).get_snapshot()

src/securejoin/bob.rs

@@ -144,10 +144,9 @@ pub(super) async fn start_protocol(context: &Context, invite: QrInvite) -> Resul
             }
 
             // If we were not in the broadcast channel before, show a 'please wait' info message.
-            // Since we don't have any specific stock string for this,
-            // use the generic `Establishing connection, please wait…`
             if !is_contact_in_chat(context, joining_chat_id, ContactId::SELF).await? {
-                let msg = stock_str::securejoin_wait(context).await;
+                let msg =
+                    stock_str::secure_join_broadcast_started(context, invite.contact_id()).await;
                 chat::add_info_msg(context, joining_chat_id, &msg).await?;
             }
             Ok(joining_chat_id)

src/stock_str.rs

@@ -429,6 +429,10 @@ https://delta.chat/donate"))]
     #[strum(props(fallback = "You joined the channel."))]
     MsgYouJoinedBroadcast = 202,
 
+    #[strum(props(fallback = "%1$s invited you to join this channel.\n\n\
+                             Waiting for the device of %2$s to reply…"))]
+    SecureJoinBroadcastStarted = 203,
+
     #[strum(props(
         fallback = "The attachment contains anonymous usage statistics, which helps us improve Delta Chat. Thank you!"
     ))]
@@ -737,6 +741,21 @@ pub(crate) async fn msg_you_joined_broadcast(context: &Context) -> String {
     translated(context, StockMessage::MsgYouJoinedBroadcast).await
 }
 
+/// Stock string: `%1$s invited you to join this channel. Waiting for the device of %2$s to reply…`.
+pub(crate) async fn secure_join_broadcast_started(
+    context: &Context,
+    inviter_contact_id: ContactId,
+) -> String {
+    if let Ok(contact) = Contact::get_by_id(context, inviter_contact_id).await {
+        translated(context, StockMessage::SecureJoinBroadcastStarted)
+            .await
+            .replace1(contact.get_display_name())
+            .replace2(contact.get_display_name())
+    } else {
+        format!("secure_join_started: unknown contact {inviter_contact_id}")
+    }
+}
+
 /// Stock string: `You reacted %1$s to "%2$s"` or `%1$s reacted %2$s to "%3$s"`.
 pub(crate) async fn msg_reacted(
     context: &Context,

test-data/golden/test_broadcast_joining_golden_bob

@@ -1,6 +1,8 @@
 InBroadcast#Chat#2002: My Channel [2 member(s)] Icon: e9b6c7a78aa2e4f415644f55a553e73.png
 --------------------------------------------------------------------------------
 Msg#2003: info (Contact#Contact#Info): Messages are end-to-end encrypted. [NOTICED][INFO]
-Msg#2004: info (Contact#Contact#Info): Establishing connection, please wait… [NOTICED][INFO]
+Msg#2004: info (Contact#Contact#Info): Alice invited you to join this channel.
+
+Waiting for the device of Alice to reply… [NOTICED][INFO]
 Msg#2007🔒:  (Contact#Contact#2001): You joined the channel. [FRESH][INFO]
 --------------------------------------------------------------------------------

test-data/golden/test_sync_broadcast_bob

@@ -1,7 +1,9 @@
 InBroadcast#Chat#2002: Channel [1 member(s)]
 --------------------------------------------------------------------------------
 Msg#2003: info (Contact#Contact#Info): Messages are end-to-end encrypted. [NOTICED][INFO]
-Msg#2004: info (Contact#Contact#Info): Establishing connection, please wait… [NOTICED][INFO]
+Msg#2004: info (Contact#Contact#Info): alice@example.org invited you to join this channel.
+
+Waiting for the device of alice@example.org to reply… [NOTICED][INFO]
 Msg#2008🔒:  (Contact#Contact#2001): You joined the channel. [FRESH][INFO]
 Msg#2010🔒:  (Contact#Contact#2001): hi [FRESH]
 Msg#2011🔒:  (Contact#Contact#2001): Member Me removed by alice@example.org. [FRESH][INFO]