nix: add clap completions

src/bin/ruptime.rs

@@ -1,6 +1,7 @@
 use anyhow::Context;
 use chrono::{Duration, Utc};
-use clap::Parser;
+use clap::{CommandFactory, Parser};
+use clap_complete::{Shell, generate};
 
 use roowho2_lib::{proto::WhodStatusUpdate, server::varlink_api::RwhodClientProxy};
 
@@ -44,12 +45,27 @@ pub struct Args {
     /// Output in JSON format
     #[arg(long, short)]
     json: bool,
+
+    /// Generate shell completion scripts for the specified shell
+    /// and print them to stdout.
+    #[arg(long, value_enum, hide = true)]
+    completions: Option<Shell>,
 }
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     let args = Args::parse();
 
+    if let Some(shell) = args.completions {
+        generate(
+            shell,
+            &mut Args::command(),
+            "ruptime",
+            &mut std::io::stdout(),
+        );
+        return Ok(());
+    }
+
     let mut conn = zlink::unix::connect("/run/roowho2/roowho2.varlink")
         .await
         .expect("Failed to connect to rwhod server");

src/bin/rwho.rs

@@ -1,5 +1,6 @@
 use anyhow::Context;
-use clap::Parser;
+use clap::{CommandFactory, Parser};
+use clap_complete::{Shell, generate};
 use roowho2_lib::{proto::WhodUserEntry, server::varlink_api::RwhodClientProxy};
 
 /// Check who is logged in on local machines.
@@ -29,12 +30,22 @@ pub struct Args {
     /// Output in JSON format
     #[arg(long, short)]
     json: bool,
+
+    /// Generate shell completion scripts for the specified shell
+    /// and print them to stdout.
+    #[arg(long, value_enum, hide = true)]
+    completions: Option<Shell>,
 }
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     let args = Args::parse();
 
+    if let Some(shell) = args.completions {
+        generate(shell, &mut Args::command(), "rwho", &mut std::io::stdout());
+        return Ok(());
+    }
+
     let mut conn = zlink::unix::connect("/run/roowho2/roowho2.varlink")
         .await
         .expect("Failed to connect to rwhod server");