feat: generate shell completions

Cargo.toml

@@ -17,6 +17,7 @@ regex = "1"
 mlua = { version = "0.9", features = ["lua54", "vendored"] }
 lazy_static = "1.4.0"
 handlebars = "4"
+clap_complete = "4.4.4"
 
 [dependencies.clap]
 version = "4"

src/app.rs

@@ -1,7 +1,8 @@
 use crate::substitution::Substitution;
 use crate::template;
-use clap::{crate_version, ArgAction};
+use clap::{crate_version, value_parser, ArgAction, ValueHint};
 use clap::{Arg, Command};
+use clap_complete::Shell;
 
 pub fn app() -> Command {
   Command::new("fblog")
@@ -17,6 +18,13 @@ pub fn app() -> Command {
         .conflicts_with("excluded-value")
         .help("adds additional values"),
     )
+    .arg(
+      Arg::new("generate-completions")
+        .long("generate-completions")
+        .action(ArgAction::Set)
+        .hide(true)
+        .value_parser(value_parser!(Shell)),
+    )
     .arg(
       Arg::new("message-key")
         .long("message-key")
@@ -92,6 +100,7 @@ pub fn app() -> Command {
       Arg::new("INPUT")
         .help("Sets the input file to use, otherwise assumes stdin")
         .required(false)
+        .value_hint(ValueHint::AnyPath)
         .default_value("-"),
     )
     .arg(

src/main.rs

@@ -12,6 +12,7 @@ mod substitution;
 mod template;
 
 use crate::log::LogSettings;
+use clap_complete::{generate, Shell};
 use std::fs;
 use substitution::Substitution;
 
@@ -21,6 +22,14 @@ fn main() {
 
   let mut log_settings = LogSettings::new_default_settings();
 
+  if let Some(generator) = matches.get_one::<Shell>("generate-completions").copied() {
+    let mut app = app::app();
+    let name = app.get_name().to_string();
+    eprintln!("Generating completion file for {generator}...");
+    generate(generator, &mut app, name, &mut io::stdout());
+    return;
+  }
+
   if let Some(values) = matches.get_many::<String>("additional-value") {
     log_settings.add_additional_values(values.map(ToOwned::to_owned).collect());
   }