xtask: add completion generation

.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+xtask = "run --package xtask --"

Cargo.lock

@@ -117,6 +117,25 @@ dependencies = [
  "strsim",
 ]
 
+[[package]]
+name = "clap_complete"
+version = "4.5.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aad5b1b4de04fead402672b48897030eec1f3bfe1550776322f59f6d6e6a5677"
+dependencies = [
+ "clap",
+]
+
+[[package]]
+name = "clap_complete_nushell"
+version = "4.5.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb8335b398d197fb3176efe9400c6c053a41733c26794316c73423d212b2f3d"
+dependencies = [
+ "clap",
+ "clap_complete",
+]
+
 [[package]]
 name = "clap_derive"
 version = "4.5.32"
@@ -625,6 +644,16 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "xtask"
+version = "0.4.0"
+dependencies = [
+ "clap",
+ "clap_complete",
+ "clap_complete_nushell",
+ "watt",
+]
+
 [[package]]
 name = "yansi"
 version = "1.0.1"

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members  = [ "watt" ]
+members  = [ "watt", "xtask" ]
 resolver = "3"
 
 [workspace.package]
@@ -15,6 +15,8 @@ version      = "0.4.0"
 anyhow                = "1.0"
 clap                  = { version = "4.0", features = [ "derive", "env" ] }
 clap-verbosity-flag   = "3.0.2"
+clap_complete         = "4.5.54"
+clap_complete_nushell = "4.5.7"
 ctrlc                 = "3.4"
 derive_more           = { version = "2.0.1", features = [ "full" ] }
 env_logger            = "0.11"

watt/lib.rs

@@ -27,9 +27,8 @@ pub enum Command {
     #[command(flatten)]
     verbosity: clap_verbosity_flag::Verbosity,
 
-    /// The daemon config path.
-    #[arg(long, env = "WATT_CONFIG")]
-    config: Option<PathBuf>,
+    #[clap(flatten)]
+    command: WattCommand,
   },
 
   /// CPU metadata and modification utility.
@@ -51,6 +50,13 @@ pub enum Command {
   },
 }
 
+#[derive(clap::Parser, Debug)]
+pub struct WattCommand {
+  /// The daemon config path.
+  #[arg(long, env = "WATT_CONFIG")]
+  config: Option<PathBuf>,
+}
+
 #[derive(clap::Parser, Debug)]
 pub enum CpuCommand {
   /// Modify CPU attributes.
@@ -79,7 +85,10 @@ pub fn main() -> anyhow::Result<()> {
     .init();
 
   match cli.command {
-    Command::Watt { config, .. } => {
+    Command::Watt {
+      command: WattCommand { config },
+      ..
+    } => {
       let config = config::DaemonConfig::load_from(config.as_deref())
         .context("failed to load daemon config")?;
 

xtask/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name                   = "xtask"
+description.workspace  = true
+version.workspace      = true
+edition.workspace      = true
+authors.workspace      = true
+rust-version.workspace = true
+publish                = false
+
+[[bin]]
+name = "xtask"
+path = "main.rs"
+
+[dependencies]
+watt.path = "../watt"
+
+clap.workspace                  = true
+clap_complete.workspace         = true
+clap_complete_nushell.workspace = true

xtask/main.rs

@@ -0,0 +1,69 @@
+use std::io;
+
+use clap::{
+  CommandFactory,
+  Parser as _,
+};
+
+#[derive(clap::Parser)]
+struct Cli {
+  #[clap(subcommand)]
+  command: Command,
+}
+
+#[derive(clap::Subcommand)]
+enum Command {
+  /// Generate completions for the specified shell.
+  GenerateCompletions {
+    #[arg(long)]
+    shell: Shell,
+
+    #[arg(long)]
+    binary: Binary,
+  },
+}
+
+#[expect(clippy::enum_variant_names)]
+#[derive(clap::ValueEnum, Debug, Clone, Copy, PartialEq, Eq)]
+enum Shell {
+  Bash,
+  Elvish,
+  Fish,
+  PowerShell,
+  Zsh,
+  Nushell,
+}
+
+#[derive(clap::ValueEnum, Debug, Clone, Copy, PartialEq, Eq)]
+enum Binary {
+  Watt,
+  Cpu,
+  Power,
+}
+
+fn main() {
+  let cli = Cli::parse();
+
+  match cli.command {
+    Command::GenerateCompletions { shell, binary } => {
+      let mut command = match binary {
+        Binary::Watt => watt::WattCommand::command(),
+        Binary::Cpu => watt::CpuCommand::command(),
+        Binary::Power => watt::PowerCommand::command(),
+      };
+      command.set_bin_name(format!("{binary:?}").to_lowercase());
+      command.build();
+
+      let shell: &dyn clap_complete::Generator = match shell {
+        Shell::Bash => &clap_complete::Shell::Bash,
+        Shell::Elvish => &clap_complete::Shell::Elvish,
+        Shell::Fish => &clap_complete::Shell::Fish,
+        Shell::PowerShell => &clap_complete::Shell::PowerShell,
+        Shell::Zsh => &clap_complete::Shell::Zsh,
+        Shell::Nushell => &clap_complete_nushell::Nushell,
+      };
+
+      shell.generate(&command, &mut io::stdout());
+    },
+  }
+}