Add shell completion

Cargo.toml

@@ -23,6 +23,8 @@ chrono = "0.4"
 parse_duration = "2.1.1"
 atty = "0.2"
 base64 = "0.22.0"
+clap_generate = "3.0.3"
+clap_complete = "4.5.1"
 
 [dev-dependencies]
 tempdir = "0.3.7"

README.md

@@ -111,6 +111,22 @@ curl <auth API> | jq -r .access_token | jwt decode -
 
 Currently the underlying token encoding and decoding library, [`jsonwebtoken`](https://github.com/Keats/jsonwebtoken), doesn't support the SEC1 private key format and requires a conversion to the PKCS8 type. You can read more from [their own README](https://github.com/Keats/jsonwebtoken/blob/8fba79b25459eacc33a80e1ee37ff8eba64079ca/README.md#convert-sec1-private-key-to-pkcs8).
 
+## Shell completion
+
+`jwt-cli` supports shell completion for `bash`, `elvish`, `fish`, `powershell`, and `zsh`. To enable it, run the following command:
+
+```sh
+source <(jwt completion bash)
+```
+
+You may want to add this to your shell profile to have it available every time you open a new shell:
+
+```sh
+if hash jwt > /dev/null; then
+  source <(jwt completion bash)
+fi
+```
+
 # Contributing
 
 I welcome all issues and pull requests! This is my first project in rust, so this project almost certainly could be better written. All I ask is that you follow the [code of conduct](code_of_conduct.md) and use [rustfmt](https://github.com/rust-lang-nursery/rustfmt) to have a consistent project code style.

src/cli_config.rs

@@ -2,6 +2,7 @@ use crate::translators::{PayloadItem, SupportedTypes, TimeFormat};
 use crate::utils::parse_duration_string;
 use chrono::format::{parse, Parsed, StrftimeItems};
 use clap::{Parser, Subcommand, ValueEnum};
+use clap_complete::Shell;
 use jsonwebtoken::Algorithm;
 use std::path::PathBuf;
 
@@ -22,6 +23,17 @@ pub enum Commands {
 
     /// Decode a JWT
     Decode(DecodeArgs),
+
+    /// Print completion
+    Completion(CompletionArgs),
+}
+
+#[derive(Debug, Clone, Parser)]
+pub struct CompletionArgs {
+    /// the shell to generate completions for
+    #[clap(value_enum)]
+    #[clap(index = 1)]
+    pub shell: Shell,
 }
 
 #[derive(Debug, Clone, Parser)]

src/main.rs

@@ -1,5 +1,7 @@
-use clap::Parser;
+use clap::{Command, CommandFactory, Parser};
+use clap_complete::{generate, Generator};
 use cli_config::{App, Commands, EncodeArgs};
+use std::io;
 use std::process::exit;
 use translators::decode::{decode_token, print_decoded_token};
 use translators::encode::{encode_token, print_encoded_token};
@@ -14,6 +16,10 @@ fn warn_unsupported(arguments: &EncodeArgs) {
     };
 }
 
+fn print_completions<G: Generator>(gen: G, cmd: &mut Command) {
+    generate(gen, cmd, cmd.get_name().to_string(), &mut io::stdout());
+}
+
 fn main() {
     let app = App::parse();
     // let matches = config_options().get_matches();
@@ -41,5 +47,10 @@ fn main() {
                 },
             );
         }
+        Commands::Completion(arguments) => {
+            let mut cmd = App::command();
+            print_completions(arguments.shell, &mut cmd);
+            exit(0)
+        }
     };
 }