feat: add clap_complete for generating completion files

`ahab generate <shell>` can now be used to generte completion files for
this tool.

Cargo.lock

@@ -8,6 +8,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "clap",
+ "clap_complete",
  "dotenvy",
 ]
 
@@ -102,6 +103,15 @@ dependencies = [
  "strsim",
 ]
 
+[[package]]
+name = "clap_complete"
+version = "4.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a04ddfaacc3bc9e6ea67d024575fafc2a813027cf374b8f24f7bc233c6b6be12"
+dependencies = [
+ "clap",
+]
+
 [[package]]
 name = "clap_derive"
 version = "4.3.0"

Cargo.toml

@@ -12,5 +12,6 @@ repository = "https://github.com/janezicmatej/ahab.git"
 
 [dependencies]
 clap = { version = "4.3.0", features = ["derive"] }
+clap_complete = "4.3.0"
 anyhow = "1.0.71"
 dotenvy = "0.15.7"

src/cli/ahab.rs

@@ -1,5 +1,6 @@
 use super::{Django, Docker, DockerCompose, Postgres};
 use clap::{Parser, Subcommand};
+use clap_complete::Shell;
 
 /// A program for interacting with various dockerized applications.
 #[derive(Parser, Debug)]
@@ -11,6 +12,12 @@ pub struct Ahab {
 
 #[derive(Debug, Subcommand)]
 pub enum Commands {
+    /// Generate completion files
+    Completion {
+        #[arg(value_enum)]
+        shell: Shell,
+    },
+
     /// Docker related subcommands
     D {
         #[command(subcommand)]

src/main.rs

@@ -1,7 +1,7 @@
 use ahab::{cli, scripts};
 
 use anyhow::Result;
-use clap::Parser;
+use clap::{CommandFactory, Parser};
 
 fn main() -> Result<()> {
     // always load dotenv on start
@@ -13,6 +13,15 @@ fn main() -> Result<()> {
     let args = cli::Ahab::parse();
 
     match args.command {
+        cli::Commands::Completion { shell } => {
+            clap_complete::generate(
+                shell,
+                &mut cli::Ahab::command(),
+                "ahab",
+                &mut std::io::stdout(),
+            );
+            Ok(())
+        }
         cli::Commands::D { command } => match command {
             cli::Docker::StopAll => scripts::docker::stop_all(),
         },