Add shell completions

Cargo.toml

@@ -15,6 +15,7 @@ anyhow = "1.0.81"
 async-trait = "0.1.79"
 chrono = "0.4.35"
 clap = { version = "~4.4", features = ["derive"] }
+clap_complete = "~4.4"
 crossbeam-channel = "0.5.12"
 enum_dispatch = "0.3.8"
 env_logger = "0.10.2"

src/main.rs

@@ -7,7 +7,7 @@ mod util;
 
 use crate::config::{Config, RepositoryMappingProducer};
 use anyhow::Result;
-use clap::Parser;
+use clap::{CommandFactory, Parser};
 use std::path::PathBuf;
 
 /// Tool for selectively mirroring Git repositories
@@ -29,6 +29,13 @@ async fn main() -> Result<()> {
 
     let cli = Cli::parse();
 
+    if let operation::Command::Completions { shell } = cli.command {
+        let mut cmd = Cli::command();
+        let name = cmd.get_name().to_string();
+        clap_complete::generate(shell, &mut cmd, name, &mut std::io::stdout());
+        return Ok(());
+    }
+
     let config = Config::load(&cli.config)?;
     log::trace!("Config = {:#?}", config);
 

src/operation/mod.rs

@@ -6,6 +6,7 @@ mod stale;
 use crate::config::RepositoryMapping;
 use anyhow::{anyhow, Result};
 use clap::Subcommand;
+use clap_complete::Shell;
 use crossbeam_channel::{select, unbounded};
 use std::{fmt, thread};
 
@@ -25,6 +26,12 @@ pub(crate) enum Command {
     /// Identify stale/unmanaged local mirrors
     #[clap(name = "stale")]
     IdentifyStale(stale::Cli),
+
+    /// Generate shell completions
+    Completions {
+        /// Shell to generate completions for
+        shell: Shell,
+    },
 }
 
 pub(crate) type CommandResult =
@@ -81,6 +88,9 @@ impl Command {
                 Command::Mirror => mirror::run(&mappings, s),
                 Command::GarbageCollect => garbage_collect::run(&mappings, s),
                 Command::IdentifyStale(args) => stale::run(&mappings, args),
+                Command::Completions { .. } => {
+                    panic!("Should not reach here when the completions subcommand was used")
+                }
             };
 
             match result {