feat: Binaries as subcommands (#2661)

* Run 'atuin-<subcmd>' if present when a given subcommand is not recognized

* Send errors to stderr

* Use String instead of OsString for external subcommands

* Remove unused import

* Move external subcommand handling up a level

* Clippy

crates/atuin/src/command/external.rs

@@ -0,0 +1,72 @@
+use std::fmt::Write as _;
+use std::process::Command;
+use std::{io, process};
+
+use clap::CommandFactory;
+use clap::builder::{StyledStr, Styles};
+use eyre::Result;
+
+use crate::Atuin;
+
+pub fn run(args: &[String]) -> Result<()> {
+    let subcommand = &args[0];
+    let bin = format!("atuin-{subcommand}");
+    let mut cmd = Command::new(&bin);
+    cmd.args(&args[1..]);
+
+    let spawn_result = match cmd.spawn() {
+        Ok(child) => Ok(child),
+        Err(e) => match e.kind() {
+            io::ErrorKind::NotFound => {
+                let output = render_not_found(subcommand, &bin);
+                Err(output)
+            }
+            _ => Err(e.to_string().into()),
+        },
+    };
+
+    match spawn_result {
+        Ok(mut child) => {
+            let status = child.wait()?;
+            if status.success() {
+                Ok(())
+            } else {
+                process::exit(status.code().unwrap_or(1));
+            }
+        }
+        Err(e) => {
+            eprintln!("{}", e.ansi());
+            process::exit(1);
+        }
+    }
+}
+
+fn render_not_found(subcommand: &str, bin: &str) -> StyledStr {
+    let mut output = StyledStr::new();
+    let styles = Styles::styled();
+    let mut atuin_cmd = Atuin::command();
+    let usage = atuin_cmd.render_usage();
+
+    let error = styles.get_error();
+    let invalid = styles.get_invalid();
+    let literal = styles.get_literal();
+
+    let _ = write!(output, "{error}error:{error:#} ");
+    let _ = write!(
+        output,
+        "unrecognized subcommand '{invalid}{subcommand}{invalid:#}' "
+    );
+    let _ = write!(
+        output,
+        "and no executable named '{invalid}{bin}{invalid:#}' found in your PATH"
+    );
+    let _ = write!(output, "\n\n");
+    let _ = write!(output, "{usage}");
+    let _ = write!(output, "\n\n");
+    let _ = write!(
+        output,
+        "For more information, try '{literal}--help{literal:#}'."
+    );
+
+    output
+}

crates/atuin/src/command/mod.rs

@@ -14,6 +14,8 @@ mod contributors;
 
 mod gen_completions;
 
+mod external;
+
 #[derive(Subcommand)]
 #[command(infer_subcommands = true)]
 pub enum AtuinCmd {
@@ -33,6 +35,9 @@ pub enum AtuinCmd {
 
     /// Generate shell completions
     GenCompletions(gen_completions::Cmd),
+
+    #[command(external_subcommand)]
+    External(Vec<String>),
 }
 
 impl AtuinCmd {
@@ -60,6 +65,7 @@ impl AtuinCmd {
                 Ok(())
             }
             Self::GenCompletions(gen_completions) => gen_completions.run(),
+            Self::External(args) => external::run(&args),
         }
     }
 }