Triagebot learns how to comment on GitHub

In this first version triagebot learns how to post a comment on GitHub
to assign priority to an issue marked as regression.

The code should allow for any kind of comment to be created.

Cargo.toml

@@ -44,6 +44,7 @@ rand = "0.8.5"
 ignore = "0.4.18"
 postgres-types = { version = "0.2.4", features = ["derive"] }
 cron = { version = "0.12.0" }
+urlencoding = "2.1.2"
 
 [dependencies.serde]
 version = "1"

src/zulip.rs

@@ -22,6 +22,7 @@ pub struct Request {
 
 #[derive(Debug, serde::Deserialize)]
 struct Message {
+    id: u64,
     sender_id: u64,
     #[allow(unused)]
     recipient_id: u64,
@@ -188,6 +189,15 @@ fn handle_command<'a>(
                                 })
                                 .unwrap(),
                             },
+                            // @triagebot prio #12345 P-high
+                            Some("prio") => return match add_comment_to_issue(&ctx, message_data, words, CommentType::AssignIssuePriority).await {
+                                Ok(r) => r,
+                                Err(e) => serde_json::to_string(&Response {
+                                    content: &format!("Failed to await at this time: {:?}", e),
+                                })
+                                .unwrap(),
+                            },
+
                             _ => {}
                         }
                     }
@@ -203,6 +213,105 @@ fn handle_command<'a>(
     })
 }
 
+#[derive(PartialEq)]
+enum CommentType {
+    AssignIssuePriority,
+}
+
+// https://docs.zulip.com/api/outgoing-webhooks#outgoing-webhook-format
+#[derive(serde::Deserialize, Debug)]
+struct ZulipReply {
+    message: ZulipMessage,
+}
+
+#[derive(serde::Deserialize, Debug)]
+struct ZulipMessage {
+    subject: String, // ex.: "[weekly] 2023-04-13"
+}
+
+async fn get_zulip_msg(ctx: &Context, id: u64) -> anyhow::Result<ZulipReply> {
+    let bot_api_token = env::var("ZULIP_API_TOKEN").expect("ZULIP_API_TOKEN");
+    let zulip_resp = ctx
+        .github
+        .raw()
+        .get(format!(
+            "https://rust-lang.zulipchat.com/api/v1/messages/{}",
+            id
+        ))
+        .basic_auth(BOT_EMAIL, Some(&bot_api_token))
+        .send()
+        .await?;
+
+    let zulip_msg_data = zulip_resp.json::<ZulipReply>().await.expect("TODO");
+    log::debug!("Zulip reply {:?}", zulip_msg_data);
+    Ok(zulip_msg_data)
+}
+
+// Add a comment to a Github issue/pr issuing a @rustbot command
+async fn add_comment_to_issue(
+    ctx: &Context,
+    message: &Message,
+    mut words: impl Iterator<Item = &str> + std::fmt::Debug,
+    ty: CommentType,
+) -> anyhow::Result<String> {
+    // retrieve the original Zulip message to build the complete URL
+    let zulip_msg = get_zulip_msg(ctx, message.id).await?;
+
+    // comment example:
+    // WG-prioritization assigning priority ([Zulip discussion](#)).
+    // @rustbot label -I-prioritize +P-XXX
+    let mut issue_id = 0;
+    let mut comment = String::new();
+    if ty == CommentType::AssignIssuePriority {
+        let zulip_stream = "245100-t-compiler/wg-prioritization/alerts";
+        let mut zulip_msg_link = format!(
+            "https://rust-lang.zulipchat.com/#narrow/stream/{}/topic/{}/near/{}",
+            zulip_stream, zulip_msg.message.subject, message.id
+        );
+        // Encode url and replace "%" with "."
+        // (apparently Zulip does that to public URLs)
+        urlencoding::encode(&zulip_msg_link);
+        zulip_msg_link = zulip_msg_link.replace("%", ".");
+
+        issue_id = words
+            .next()
+            .unwrap()
+            .replace("#", "")
+            .parse::<u64>()
+            .unwrap();
+        let p_label = words.next().unwrap();
+
+        comment = format!(
+            "WG-prioritization assigning priority ([Zulip discussion]({}))
+            \n\n@rustbot label -I-prioritize +{}",
+            zulip_msg_link, p_label
+        );
+    }
+    // else ... handle other comment type
+
+    let github_resp = ctx
+        .octocrab
+        .issues("owner", "repo")
+        .create_comment(issue_id.clone(), comment.clone())
+        .await;
+
+    let _reply = match github_resp {
+        Ok(data) => data,
+        Err(e) => {
+            return Ok(serde_json::to_string(&Response {
+                content: &format!("Failed to post comment on Github: {:?}.", e),
+            })
+            .unwrap());
+        }
+    };
+    log::debug!("Created comment on issue #{}: {:?}", issue_id, comment);
+
+    Ok(serde_json::to_string(&ResponseNotRequired {
+        response_not_required: true,
+    })
+    .unwrap())
+}
+
 // This does two things:
 //  * execute the command for the other user
 //  * tell the user executed for that a command was run as them by the user