#[macro_use]
extern crate yasec_derive;
extern crate yasec;

use std::error::Error as StdError;
use yasec::Yasec;

#[derive(Yasec)]
pub struct DB {
    pub host: String,
    pub port: u16,
}

#[derive(Yasec)]
pub struct Vendor {
    #[yasec(from = "API_KEY")]
    pub key: String,
    #[yasec(from = "API_SECRET")]
    pub secret: String,
}

#[derive(Yasec)]
pub struct Config {
    db: DB,
    vendor: Vendor,
    #[yasec(default = 8080)]
    listen_port: u16,
    callback_url: Option<String>,
    mode: Mode,
}

pub enum Mode {
    Client,
    Server,
}

impl Yasec for Mode {
    fn parse(s: &str) -> Result<Self, Box<dyn StdError>> {
        match s {
            "CLIENT" => Ok(Self::Client),
            "SERVER" => Ok(Self::Server),
            _ => Err(yasec::ParseError::new(s).into()),
        }
    }
}

fn main() {
    // Assuming the following environment variables are set
    std::env::set_var("DB_HOST", "127.0.0.1");
    std::env::set_var("DB_PORT", "5432");
    std::env::set_var("API_KEY", "0912xn819b8s1029s");
    std::env::set_var("API_SECRET", "zyYWn5pPtLcDSaFWQEu0nf1cf0eYNN8j");
    std::env::set_var("MODE", "SERVER");
    std::env::remove_var("LISTEN_PORT");
    std::env::remove_var("CALLBACK_URL");

    // Initialize config from environment variables or terminate the process.
    let config = Config::init().unwrap();

    assert_eq!(config.db.host, "127.0.0.1");
    assert_eq!(config.db.port, 5432);
    assert_eq!(config.vendor.key, "0912xn819b8s1029s");
    assert_eq!(config.vendor.secret, "zyYWn5pPtLcDSaFWQEu0nf1cf0eYNN8j");
    assert_eq!(config.listen_port, 8080);
    assert_eq!(config.callback_url, None);
    match config.mode {
        Mode::Server => (),
        _ => panic!("Unexpected value of Mode"),
    }
}