use std::env;
use std::fs::File;
use std::io::Read;

extern crate jsonwebtoken as jwt;
#[macro_use]
extern crate serde_derive;
extern crate serde_json;

use jwt::{decode, Validation, Algorithm};

#[derive(Debug, Serialize, Deserialize)]
struct Claims {
    aud: String,
    exp: u64,
    iss: String,
    sub: String,
    scope: String,
}

fn main() {
    let args: Vec<String> = env::args().collect();

    let keyfile = &args[1];
    println!("reading key from {}", keyfile);
    let mut f = File::open(keyfile).unwrap();

    let mut key = Vec::new();
    f.read_to_end(&mut key).unwrap();
    println!("key len {}", key.len());

    println!("finding tokens on command line");
    let token = &args[2];
    println!("token {}", token);
    decode_token(&token, &key);
}


fn decode_token(token: &str, key: &[u8]) {
    let v = Validation::new(Algorithm::RS512);
    let data = match decode::<Claims>(&token, key, &v) {
        Ok(c) => c,
        Err(err) => match *err.kind() {
            _ => {
                eprintln!("ERROR: {:?}", err);
                panic!();
            },
        },
    };
    let claims = data.claims;
    let j = serde_json::to_string_pretty(&claims).expect("JSON error");
    println!("{}", j);
}