refactor(cli): simplify applet detection and remove feature-based defaults

crates/irtt-cli/src/applet.rs

@@ -1,4 +1,6 @@
-use std::path::Path;
+use std::{ffi::OsString, path::Path};
+
+use clap::Command;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum RequestedApplet {
@@ -7,20 +9,17 @@ pub enum RequestedApplet {
     Server,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum AppletAvailability {
-    Client,
-    Tui,
-    Server,
-    None,
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AppletDispatch {
+    Run {
+        applet: RequestedApplet,
+        argv: Vec<OsString>,
+    },
+    Help(String),
 }
 
 pub fn detect_applet_from_argv0(argv0: &str) -> Option<RequestedApplet> {
-    match Path::new(argv0)
-        .file_name()
-        .and_then(|name| name.to_str())
-        .unwrap_or(argv0)
-    {
+    match applet_basename(argv0) {
         "irtt-cli" => Some(RequestedApplet::Client),
         "irtt-tui" => Some(RequestedApplet::Tui),
         "irttd" | "irtt-server" => Some(RequestedApplet::Server),
@@ -29,20 +28,73 @@ pub fn detect_applet_from_argv0(argv0: &str) -> Option<RequestedApplet> {
     }
 }
 
-pub const fn default_applet_for_features(
-    client_enabled: bool,
-    tui_enabled: bool,
-    server_enabled: bool,
-) -> AppletAvailability {
-    if client_enabled {
-        AppletAvailability::Client
-    } else if tui_enabled {
-        AppletAvailability::Tui
-    } else if server_enabled {
-        AppletAvailability::Server
-    } else {
-        AppletAvailability::None
+pub fn dispatch_from_argv(argv: Vec<OsString>) -> Result<AppletDispatch, String> {
+    let argv0 = argv
+        .first()
+        .and_then(|arg| arg.to_str())
+        .unwrap_or("irtt-rs");
+
+    if let Some(applet) = detect_applet_from_argv0(argv0) {
+        return Ok(AppletDispatch::Run { applet, argv });
     }
+
+    let basename = applet_basename(argv0);
+    if basename.starts_with("irtt-") && basename != "irtt-rs" {
+        return Err(format!(
+            "unknown applet name '{basename}'. Known applet names: irtt-rs, irtt-cli, irtt-tui, irtt-server"
+        ));
+    }
+
+    let Some(command) = argv.get(1).and_then(|arg| arg.to_str()) else {
+        return Err(format!(
+            "choose an applet: client, tui, or server\n\n{}",
+            dispatcher_help()
+        ));
+    };
+
+    match command {
+        "-h" | "--help" => Ok(AppletDispatch::Help(dispatcher_help())),
+        "client" => Ok(AppletDispatch::Run {
+            applet: RequestedApplet::Client,
+            argv: applet_argv("irtt-cli", &argv[2..]),
+        }),
+        "tui" => Ok(AppletDispatch::Run {
+            applet: RequestedApplet::Tui,
+            argv: applet_argv("irtt-tui", &argv[2..]),
+        }),
+        "server" => Ok(AppletDispatch::Run {
+            applet: RequestedApplet::Server,
+            argv: applet_argv("irtt-server", &argv[2..]),
+        }),
+        _ => Err(format!(
+            "unknown applet '{command}'. Choose one of: client, tui, server\n\n{}",
+            dispatcher_help()
+        )),
+    }
+}
+
+pub fn dispatcher_help() -> String {
+    let mut command = Command::new("irtt-rs")
+        .about("IRTT-compatible multi-applet dispatcher")
+        .subcommand(Command::new("client").about("Run the stream client applet"))
+        .subcommand(Command::new("tui").about("Run the terminal UI applet"))
+        .subcommand(Command::new("server").about("Run the server applet"))
+        .after_help("Applet binary names: irtt-cli, irtt-tui, irtt-server");
+    command.render_help().to_string()
+}
+
+fn applet_basename(argv0: &str) -> &str {
+    Path::new(argv0)
+        .file_name()
+        .and_then(|name| name.to_str())
+        .unwrap_or(argv0)
+}
+
+fn applet_argv(applet_name: &str, args: &[OsString]) -> Vec<OsString> {
+    let mut argv = Vec::with_capacity(args.len() + 1);
+    argv.push(OsString::from(applet_name));
+    argv.extend(args.iter().cloned());
+    argv
 }
 
 #[cfg(test)]

crates/irtt-cli/src/main.rs

@@ -6,9 +6,7 @@ use std::{
 };
 
 use irtt_cli::{
-    applet::{
-        default_applet_for_features, detect_applet_from_argv0, AppletAvailability, RequestedApplet,
-    },
+    applet::{dispatch_from_argv, AppletDispatch, RequestedApplet},
     signal::install_signal_handler,
 };
 
@@ -44,15 +42,6 @@ fn run_from_env() -> Result<(), Box<dyn std::error::Error>> {
     }
 }
 
-fn default_requested_applet() -> Result<RequestedApplet, Box<dyn std::error::Error>> {
-    match default_applet_for_features(cfg!(feature = "client"), cfg!(feature = "tui"), false) {
-        AppletAvailability::Client => Ok(RequestedApplet::Client),
-        AppletAvailability::Tui => Ok(RequestedApplet::Tui),
-        AppletAvailability::Server => Ok(RequestedApplet::Server),
-        AppletAvailability::None => Err("no runnable applet is available in this build".into()),
-    }
-}
-
 #[cfg(feature = "client")]
 fn run_client_applet(
     argv: Vec<OsString>,