feat(shell): add a proper standard shell autocomplete generation subcommand

Author: alexpasmantier

television/cli/args.rs

@@ -673,6 +673,12 @@ pub enum Command {
         #[arg(value_enum)]
         shell: Shell,
     },
+    /// Generates standard shell tab-completion scripts for tv's various subcommands.
+    #[clap(name = "completions")]
+    Completions {
+        #[arg(value_enum)]
+        shell: Shell,
+    },
     /// Downloads the latest collection of channel prototypes from github
     /// and saves them to the local configuration directory.
     UpdateChannels {

television/main.rs

@@ -23,6 +23,7 @@ use television::{
     utils::{
         shell::{
             Shell, completion_script, render_autocomplete_script_template,
+            render_clap_autocomplete,
         },
         stdin::is_readable_stdin,
     },
@@ -146,6 +147,18 @@ pub fn handle_subcommand(
             let _ = writeln!(stdout().lock(), "{script}");
             exit(0);
         }
+        Command::Completions { shell } => {
+            let target_shell = Shell::from(shell);
+            if let Some(script) = render_clap_autocomplete(target_shell) {
+                let _ = writeln!(stdout().lock(), "{script}");
+            } else {
+                eprintln!(
+                    "Shell completions are not supported for {target_shell}"
+                );
+                exit(1);
+            }
+            exit(0);
+        }
         Command::UpdateChannels { force } => {
             update_local_channels(force)?;
             exit(0);

television/utils/shell.rs

@@ -238,7 +238,7 @@ pub fn render_autocomplete_script_template(
     Ok(clap_autocomplete + &script)
 }
 
-fn render_clap_autocomplete(shell: Shell) -> Option<String> {
+pub fn render_clap_autocomplete(shell: Shell) -> Option<String> {
     // Clap autocomplete
     let mut clap_autocomplete = vec![];
     let mut cmd = Cli::command();