feat: add shell completions command (#12)

- Add `clap_complete` dependency
- Add `completions` subcommand to generate shell completions
- Supported shells: bash, zsh, fish, powershell, elvish
- Usage: gitclaw completions <shell>

Part of v0.2.0 phase 1 (shell completions).

Author: clawdeeo

Cargo.lock

@@ -5,6 +5,7 @@ edition = "2021"
 
 [dependencies]
 clap = { version = "=4.4.18", features = ["derive", "env"] }
+clap_complete = "=4.4.5"
 tokio = { version = "=1.32", features = ["rt-multi-thread", "macros"] }
 reqwest = { version = "=0.11.22", default-features = false, features = ["json", "rustls-tls", "stream"] }
 serde = { version = "=1.0.188", features = ["derive"] }

Cargo.toml

@@ -1,4 +1,5 @@
 use clap::{Parser, Subcommand};
+use clap_complete::Shell;
 
 #[derive(Parser)]
 #[command(name = "gitclaw", about = "Install software from GitHub releases")]
@@ -34,4 +35,8 @@ pub enum Commands {
         #[arg(short, long, default_value = "10")]
         limit: usize,
     },
+    Completions {
+        #[arg(value_enum)]
+        shell: Shell,
+    },
 }

src/cli.rs

@@ -1,4 +1,5 @@
-use clap::Parser;
+use clap::{CommandFactory, Parser};
+use clap_complete::generate;
 
 mod cli;
 mod config;
@@ -70,6 +71,11 @@ async fn run(cli: Cli, config: Config) -> anyhow::Result<()> {
         Commands::Search { package, limit } => {
             github::search_releases(&package, limit, &config).await?
         }
+        Commands::Completions { shell } => {
+            let mut cmd = Cli::command();
+            let name = cmd.get_name().to_string();
+            generate(shell, &mut cmd, name, &mut std::io::stdout());
+        }
     }
 
     Ok(())