Add shell completions

Cargo.toml

@@ -18,6 +18,7 @@ bindle = { workspace = true }
 bytes = "1.1"
 chrono = "0.4"
 clap = { version = "3.2.24", features = ["derive", "env"] }
+clap_complete = "3.1.4"
 clearscreen = "2.0.1"
 command-group = "2.1"
 comfy-table = "5.0"

src/bin/spin.rs

@@ -8,6 +8,7 @@ use spin_cli::commands::{
     cloud::{DeployCommand, LoginCommand},
     doctor::DoctorCommand,
     external::execute_external_subcommand,
+    generate_completions::GenerateCompletionsCommand,
     new::{AddCommand, NewCommand},
     plugins::PluginCommands,
     registry::RegistryCommands,
@@ -129,6 +130,8 @@ enum SpinApp {
     Plugins(PluginCommands),
     #[clap(subcommand, hide = true)]
     Trigger(TriggerCommands),
+    #[clap(hide = true, name = "generate-completions")]
+    GenerateCompletions(GenerateCompletionsCommand),
     #[clap(external_subcommand)]
     External(Vec<String>),
     Watch(WatchCommand),
@@ -162,6 +165,7 @@ impl SpinApp {
             Self::External(cmd) => execute_external_subcommand(cmd, app).await,
             Self::Watch(cmd) => cmd.run().await,
             Self::Doctor(cmd) => cmd.run().await,
+            Self::GenerateCompletions(cmd) => cmd.run(SpinApp::into_app()).await,
         }
     }
 }

src/commands.rs

@@ -8,6 +8,8 @@ pub mod cloud;
 pub mod doctor;
 /// Commands for external subcommands (i.e. plugins)
 pub mod external;
+/// Command to generate shell completions
+pub mod generate_completions;
 /// Command for creating a new application.
 pub mod new;
 /// Command for adding a plugin to Spin

src/commands/generate_completions.rs

@@ -0,0 +1,22 @@
+use anyhow::Result;
+use clap::Parser;
+
+/// Generate shell completions.
+#[derive(Parser, Debug)]
+#[clap(about = "Generate completions")]
+pub struct GenerateCompletionsCommand {
+    #[clap(value_parser = clap::value_parser!(clap_complete::Shell))]
+    pub shell: clap_complete::Shell,
+}
+
+impl GenerateCompletionsCommand {
+    pub async fn run(&self, mut cmd: clap::Command<'_>) -> Result<()> {
+        // let mut cmd: clap::Command = SpinApp::into_app();
+        print_completions(self.shell, &mut cmd);
+        Ok(())
+    }
+}
+
+fn print_completions<G: clap_complete::Generator>(gen: G, cmd: &mut clap::Command) {
+    clap_complete::generate(gen, cmd, cmd.get_name().to_string(), &mut std::io::stdout())
+}