tide 0.3.0

use fnv::FnvHashMap;
use futures::future::{BoxFuture, FutureExt};
use http_service::Body;
use route_recognizer::{Match, Params, Router as MethodRouter};

use crate::{
    endpoint::{DynEndpoint, Endpoint},
    Context, Response,
};

/// The routing table used by `App`
///
/// Internally, we have a separate state machine per http method; indexing
/// by the method first allows the table itself to be more efficient.
#[allow(missing_debug_implementations)]
pub(crate) struct Router<State> {
    method_map: FnvHashMap<http::Method, MethodRouter<Box<DynEndpoint<State>>>>,
}

/// The result of routing a URL
pub(crate) struct Selection<'a, State> {
    pub(crate) endpoint: &'a DynEndpoint<State>,
    pub(crate) params: Params,
}

impl<State: 'static> Router<State> {
    pub(crate) fn new() -> Router<State> {
        Router {
            method_map: FnvHashMap::default(),
        }
    }

    pub(crate) fn add(&mut self, path: &str, method: http::Method, ep: impl Endpoint<State>) {
        self.method_map
            .entry(method)
            .or_insert_with(MethodRouter::new)
            .add(path, Box::new(move |cx| ep.call(cx).boxed()))
    }

    pub(crate) fn route(&self, path: &str, method: http::Method) -> Selection<'_, State> {
        if let Some(Match { handler, params }) = self
            .method_map
            .get(&method)
            .and_then(|r| r.recognize(path).ok())
        {
            Selection {
                endpoint: &**handler,
                params,
            }
        } else if method == http::Method::HEAD {
            // If it is a HTTP HEAD request then check if there is a callback in the endpoints map
            // if not then fallback to the behavior of HTTP GET else proceed as usual

            self.route(path, http::Method::GET)
        } else {
            Selection {
                endpoint: &not_found_endpoint,
                params: Params::new(),
            }
        }
    }
}

fn not_found_endpoint<Data>(_cx: Context<Data>) -> BoxFuture<'static, Response> {
    box_async! {
        http::Response::builder().status(http::StatusCode::NOT_FOUND).body(Body::empty()).unwrap()
    }
}