Show Zulip details in 'show-person'.

Show `zulip_id` if present.

In addition, if ZULIP_USER and ZULIP_TOKEN are set, try to look up the
user's name (as shown in Zulip itself). This is useful for finding
people whose Zulip name differs from their GitHub name.

src/main.rs

@@ -13,6 +13,7 @@ const USER_AGENT: &str = "https://github.com/rust-lang/team (infra@rust-lang.org
 
 use data::Data;
 use schema::{Email, Team, TeamKind};
+use zulip::ZulipApi;
 
 use crate::schema::RepoPermission;
 use anyhow::{bail, format_err, Error};
@@ -292,8 +293,23 @@ fn run() -> Result<(), Error> {
             println!();
 
             println!("github: @{}", person.github());
+            if let Some(zulip_id) = person.zulip_id() {
+                let zulip = ZulipApi::new();
+                match zulip.require_auth() {
+                    Ok(()) => match zulip.get_user(zulip_id) {
+                        Ok(user) => println!("zulip: {} ({zulip_id})", user.name),
+                        Err(err) => {
+                            println!("zulip_id: {zulip_id}  # Failed to look up Zulip name: {err}")
+                        }
+                    },
+                    Err(err) => {
+                        // We have no authentication credentials, so don't even attempt the network access.
+                        println!("zulip_id: {zulip_id}  # Skipped name lookup: {err}");
+                    }
+                }
+            }
             if let Email::Present(email) = person.email() {
-                println!("email:  {}", email);
+                println!("email: {}", email);
             }
             println!();
 

src/zulip.rs

@@ -36,11 +36,7 @@ impl ZulipApi {
 
     pub(crate) fn require_auth(&self) -> Result<(), Error> {
         if self.auth.is_none() {
-            bail!(
-                "missing {} and/or {} environment variables",
-                USER_VAR,
-                TOKEN_VAR
-            );
+            bail!("missing {USER_VAR} and/or {TOKEN_VAR} environment variables");
         }
         Ok(())
     }
@@ -56,6 +52,17 @@ impl ZulipApi {
         Ok(response)
     }
 
+    /// Get a single user of the Rust Zulip instance
+    pub(crate) fn get_user(&self, user_id: u64) -> Result<ZulipUser, Error> {
+        let response = self
+            .req(Method::GET, &format!("/users/{user_id}"), None)?
+            .error_for_status()?
+            .json::<ZulipOneUser>()?
+            .user;
+
+        Ok(response)
+    }
+
     /// Perform a request against the Zulip API
     fn req(
         &self,
@@ -78,12 +85,18 @@ impl ZulipApi {
     }
 }
 
-/// A collection of Zulip users
+/// A collection of Zulip users, as returned from '/users'
 #[derive(Deserialize)]
 struct ZulipUsers {
     members: Vec<ZulipUser>,
 }
 
+/// A collection of exactly one Zulip user, as returned from '/users/{user_id}'
+#[derive(Deserialize)]
+struct ZulipOneUser {
+    user: ZulipUser,
+}
+
 /// A single Zulip user
 #[derive(Clone, Deserialize, PartialEq, Eq, Hash)]
 pub(crate) struct ZulipUser {