Add CLI tool

Cargo.toml

@@ -39,6 +39,8 @@ x509-cert = { version = "0.1.1", features = ["pem"] }
 
 ssi-jwk = { version = "0.1" }
 isomdl-macros = { version = "0.1.0", path = "macros" }
+clap = { version = "4", features = ["derive"] }
+clap-stdin = "0.2.1"
 
 [dependencies.cose-rs]
 git = "https://github.com/spruceid/cose-rs"

README.md

@@ -1,3 +1,16 @@
 # isomdl
 
 ISO mDL implementation in Rust
+
+## CLI tool
+
+This crate contains a CLI tool. Run the `--help` command to see what actions you can perform.
+
+```bash
+cargo run -- --help
+```
+
+For example you can get the namespaces and elements defined in an mDL:
+```bash
+cat test/stringified-mdl.txt | cargo run -- get-namespaces -
+```

src/main.rs

@@ -0,0 +1,48 @@
+use std::collections::BTreeMap;
+
+use anyhow::{Context, Error};
+use clap::Parser;
+use clap_stdin::MaybeStdin;
+use isomdl::presentation::{device::Document, Stringify};
+
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    #[command(subcommand)]
+    action: Action,
+}
+
+#[derive(Debug, clap::Subcommand)]
+enum Action {
+    /// Print the namespaces and element identifiers used in an mDL.
+    GetNamespaces {
+        /// Base64 encoded mDL in the format used in the issuance module of this crate.
+        mdl: MaybeStdin<String>,
+    },
+}
+
+fn main() -> Result<(), Error> {
+    match Args::parse().action {
+        Action::GetNamespaces { mdl } => print_namespaces(mdl.to_string()),
+    }
+}
+
+fn print_namespaces(mdl: String) -> Result<(), Error> {
+    let claims = Document::parse(mdl)
+        .context("could not parse mdl")?
+        .namespaces
+        .into_inner()
+        .into_iter()
+        .map(|(ns, inner)| (ns, inner.into_inner().into_keys().collect()))
+        .collect::<BTreeMap<String, Vec<String>>>();
+    println!("{}", serde_json::to_string_pretty(&claims)?);
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn print_namespaces() {
+        super::print_namespaces(include_str!("../test/stringified-mdl.txt").to_string()).unwrap()
+    }
+}