use std::collections::HashMap;
use json::JsonValue;
use std::future::Future;
use futures::future::BoxFuture;

pub trait Handler: Send + Sync + 'static {
    fn handle(&self, _: JsonValue) -> BoxFuture<'static, ()>;
}

impl<C, F> Handler for C
where C: Send + Sync + 'static + Fn(JsonValue) -> F,
      F: Future<Output = ()> + 'static + Send {
    fn handle(&self, req: JsonValue) -> BoxFuture<'static, ()> {
        Box::pin((*self)(req))
    }
}

pub struct UpdateRouter {
    router: HashMap<String, Box<dyn Handler>>,
    rt: tokio::runtime::Handle,
}

impl UpdateRouter {
    pub fn new(rt: tokio::runtime::Handle) -> Self {
        Self {
            router: HashMap::new(),
            rt: rt
        }
    }
    pub fn add_handler<H: Handler>(&mut self, update_type: &str, handler: H) {
        self.router.insert(update_type.to_owned(), Box::new(handler));
    }

    pub fn dispatch(&self, update: JsonValue) {
        let update_type: &str = update["@type"].as_str().unwrap();
        self.router.get(update_type)
            .and_then(|handler| { self.rt.spawn(handler.handle(update)); Some(()) })
            .or_else(|| { println!("handler not found"); Some(()) });
    }
}