saphir 2.0.0-alpha

Fully async-await http server framework
Documentation 
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//! Controllers are responsible for handling requests and returning responses to the client.
//!
//! More specifically a Controller defines a list of endpoint (Handlers) that handle a request and
//! return a Future of a [`Responder`](../responder/trait.Responder.html).
//! The [`Responder`](../responder/trait.Responder.html) is responsible for the
//! [`Response`](../response/struct.Response.html) being generated
//!
//! To create a controller, simply implement the [Controller](trait.Controller.html) trait on a struct:
//! ```rust
//! use saphir::prelude::*;
//!
//! struct BasicController;
//!
//! impl Controller for BasicController {
//!     const BASE_PATH: &'static str = "/basic";
//!
//!     fn handlers(&self) -> Vec<ControllerEndpoint<Self>>
//!     where
//!         Self: Sized {
//!         EndpointsBuilder::new()
//!             .add(Method::GET, "/healthz", BasicController::healthz)
//!             .build()
//!     }
//! }
//!
//! impl BasicController {
//!     async fn healthz(&self, req: Request<Body>) -> impl Responder {200}
//! }
//! ```
//!
//! *SAFETY NOTICE*
//!
//! Inside the controller we need a little bit of unsafe code. This code allow us to consider
//! the futures generated by the controller handlers as 'static. This is considered safe since every
//! controller lives within the server stack which has a static lifetime over your application.
//! We plan to remove this unsafe code as soon as we find another solution to it.

use crate::{
    request::Request,
    responder::{DynResponder, Responder},
};
use futures::future::BoxFuture;
use futures_util::future::{Future, FutureExt};
use http::Method;
use hyper::Body;

/// Type definition to represent a endpoint within a controller
pub type ControllerEndpoint<C> = (
    Method,
    &'static str,
    Box<dyn DynControllerHandler<C, Body> + Send + Sync>,
);

/// Trait that defines how a controller handles its requests
pub trait Controller {
    /// Defines the base path from which requests are to be handled by this controller
    const BASE_PATH: &'static str;

    /// Returns a list of [`ControllerEndpoint`](type.ControllerEndpoint.html)
    ///
    /// Each [`ControllerEndpoint`](type.ControllerEndpoint.html) is then added to the router, which
    /// will dispatch requests accordingly
    fn handlers(&self) -> Vec<ControllerEndpoint<Self>>
        where
            Self: Sized;
}

/// Trait the defines a handle within a controller.
/// This trait is not meant to be implemented manually as there is a blanket implementation for Async Fns
pub trait ControllerHandler<C, B> {
    /// An instance of a [`Responder`](../responder/trait.Responder.html) being returned by the handler
    type Responder: Responder;
    ///
    type Future: Future<Output=Self::Responder>;

    /// Handle the request dispatched from the [`Router`](../router/struct.Router.html)
    fn handle(&self, controller: &C, req: Request<B>) -> Self::Future;
}

///
pub trait DynControllerHandler<C, B> {
    ///
    fn dyn_handle(&self, controller: &C, req: Request<B>) -> BoxFuture<'static, Box<dyn DynResponder>>;
}

/// Builder to simplify returning a list of endpoint in the `handlers` method of the controller trait
#[derive(Default)]
pub struct EndpointsBuilder<C: Controller> {
    handlers: Vec<ControllerEndpoint<C>>,
}

impl<C: Controller> EndpointsBuilder<C> {
    /// Create a new endpoint builder
    #[inline]
    pub fn new() -> Self {
        Self {
            handlers: Default::default(),
        }
    }

    /// Add a endpoint the the builder
    ///
    /// ```rust
    ///# use saphir::prelude::*;
    ///
    ///# struct BasicController;
    ///
    ///# impl Controller for BasicController {
    ///#     const BASE_PATH: &'static str = "/basic";
    ///#
    ///#     fn handlers(&self) -> Vec<ControllerEndpoint<Self>>
    ///#     where
    ///#         Self: Sized {
    ///#         EndpointsBuilder::new()
    ///#             .add(Method::GET, "/healthz", BasicController::healthz)
    ///#             .build()
    ///#     }
    ///# }
    ///#
    /// impl BasicController {
    ///     async fn healthz(&self, req: Request<Body>) -> impl Responder {200}
    /// }
    ///
    /// let b: EndpointsBuilder<BasicController> = EndpointsBuilder::new().add(Method::GET, "/healthz", BasicController::healthz);
    /// ```
    #[inline]
    pub fn add<H>(mut self, method: Method, route: &'static str, handler: H) -> Self
        where
            H: 'static + DynControllerHandler<C, Body> + Send + Sync,
    {
        self.handlers.push((method, route, Box::new(handler)));
        self
    }

    /// Finish the builder into a `Vec<ControllerEndpoint<C>>`
    #[inline]
    pub fn build(self) -> Vec<ControllerEndpoint<C>> {
        self.handlers
    }
}


impl<C, B, Fun, Fut, R> ControllerHandler<C, B> for Fun
    where
        C: 'static,
        Fun: Fn(&'static C, Request<B>) -> Fut,
        Fut: 'static + Future<Output=R> + Send,
        R: Responder,
{
    type Responder = R;
    type Future = Box<dyn Future<Output=Self::Responder> + Unpin + Send>;

    #[inline]
    fn handle(&self, controller: &C, req: Request<B>) -> Self::Future {
        // # SAFETY #
        // The controller is initialized in static memory when calling run on Server.
        let controller = unsafe { std::mem::transmute::<&'_ C, &'static C>(controller) };
        Box::new(Box::pin((*self)(controller, req)))
    }
}

impl<C, T, H, Fut, R> DynControllerHandler<C, T> for H
    where
        R: 'static + Responder,
        Fut: 'static + Future<Output=R> + Unpin + Send,
        H: ControllerHandler<C, T, Future=Fut, Responder=R>,
{
    #[inline]
    fn dyn_handle(&self, controller: &C, req: Request<T>) -> BoxFuture<'static, Box<dyn DynResponder>> {
        self.handle(controller, req)
            .map(|r| Box::new(Some(r)) as Box<dyn DynResponder>)
            .boxed()
    }
}