Move printing completions to main

wutag_cli/src/main.rs

@@ -4,11 +4,12 @@ mod config;
 mod fmt;
 mod opt;
 
-use clap::Parser;
+use clap::{CommandFactory, Parser};
 
 use app::App;
 use config::Config;
-use opt::Opts;
+use opt::{Command, CompletionsOpts, Opts, Shell, APP_NAME};
+use std::io;
 use thiserror::Error as ThisError;
 
 #[derive(Debug, ThisError)]
@@ -29,10 +30,38 @@ pub enum Error {
 
 pub type Result<T> = std::result::Result<T, Error>;
 
+fn print_completions(opts: &CompletionsOpts) -> Result<()> {
+    use clap_complete::{
+        generate,
+        shells::{Bash, Elvish, Fish, PowerShell, Zsh},
+    };
+
+    let mut app = Opts::command();
+
+    match opts.shell {
+        Shell::Bash => generate(Bash, &mut app, APP_NAME, &mut io::stdout()),
+        Shell::Elvish => generate(Elvish, &mut app, APP_NAME, &mut io::stdout()),
+        Shell::Fish => generate(Fish, &mut app, APP_NAME, &mut io::stdout()),
+        Shell::PowerShell => generate(PowerShell, &mut app, APP_NAME, &mut io::stdout()),
+        Shell::Zsh => generate(Zsh, &mut app, APP_NAME, &mut io::stdout()),
+    }
+    Ok(())
+}
+
 fn main() {
     let config = Config::load_default_location().unwrap_or_default();
+    let opts = Opts::parse();
+
+    if let Command::PrintCompletions(opts) = &opts.cmd {
+        if let Err(e) = print_completions(opts) {
+            eprintln!("Execution failed, reason: {}", e);
+            std::process::exit(1);
+        } else {
+            std::process::exit(0);
+        }
+    }
 
-    if let Err(e) = App::run(Opts::parse(), config) {
+    if let Err(e) = App::run(opts, config) {
         eprintln!("Execution failed, reason: {}", e);
     }
 }