From 8cdea32a2b36b1015dc2476d94e434b56155c207 Mon Sep 17 00:00:00 2001
From: skippy10110 <pmlyon@hotmail.ca>
Date: Mon, 14 Mar 2022 17:35:08 -0300
Subject: [PATCH] After renaming zulip topic (#1588), post an additional
 comment under the old (now empty) topic pointing to the newly renamed topic.
 Fixes #1228.

---
 src/handlers/major_change.rs | 22 ++++++++++++++++++++++
 src/zulip.rs                 |  9 +++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/handlers/major_change.rs b/src/handlers/major_change.rs
index 5b5016c62..a6e1366ff 100644
--- a/src/handlers/major_change.rs
+++ b/src/handlers/major_change.rs
@@ -147,6 +147,28 @@ pub(super) async fn handle_input(
                 .await
                 .context("zulip message update failed")?;
 
+            // after renaming the zulip topic, post an additional comment under the old topic with a url to the new, renamed topic
+            // this is necessary due to the lack of topic permalinks, see https://github.com/zulip/zulip/issues/15290
+            let new_topic_url = crate::zulip::Recipient::Stream {
+                id: config.zulip_stream,
+                topic: &new_topic,
+            }.url();
+            let breadcrumb_comment = format!(
+                "The associated GitHub issue has been renamed. Please see the [renamed Zulip topic]({}).",
+                new_topic_url
+            );
+            let zulip_send_breadcrumb_req = crate::zulip::MessageApiRequest {
+                recipient: crate::zulip::Recipient::Stream {
+                    id: config.zulip_stream,
+                    topic: &prev_topic,
+                },
+                content: &breadcrumb_comment,
+            };
+            zulip_send_breadcrumb_req
+                .send(&ctx.github.raw())
+                .await
+                .context("zulip post failed")?;
+
             return Ok(());
         }
     };
diff --git a/src/zulip.rs b/src/zulip.rs
index c9cb2fa07..1d74930b1 100644
--- a/src/zulip.rs
+++ b/src/zulip.rs
@@ -393,6 +393,10 @@ impl Recipient<'_> {
             Recipient::Private { id, .. } => format!("pm-with/{}-xxx", id),
         }
     }
+
+    pub fn url(&self) -> String {
+        format!("https://rust-lang.zulipchat.com/#narrow/{}", self.narrow())
+    }
 }
 
 #[cfg(test)]
@@ -430,10 +434,7 @@ pub struct MessageApiRequest<'a> {
 
 impl<'a> MessageApiRequest<'a> {
     pub fn url(&self) -> String {
-        format!(
-            "https://rust-lang.zulipchat.com/#narrow/{}",
-            self.recipient.narrow()
-        )
+        self.recipient.url()
     }
 
     pub async fn send(&self, client: &reqwest::Client) -> anyhow::Result<reqwest::Response> {