use std::error::Error as StdError;

use std::fmt;

use std::future::Future;

use std::marker::PhantomData;

use crate::body::Body;

use crate::service::service::Service;

use crate::{Request, Response};

/// Create a `Service` from a function.

///

/// # Example

///

/// ```

/// use bytes::Bytes;

/// use hyper::{body, Request, Response, Version};

/// use http_body_util::Full;

/// use hyper::service::service_fn;

///

/// let service = service_fn(|req: Request<body::Incoming>| async move {

///     if req.version() == Version::HTTP_11 {

///         Ok(Response::new(Full::<Bytes>::from("Hello World")))

///     } else {

///         // Note: it's usually better to return a Response

///         // with an appropriate StatusCode instead of an Err.

///         Err("not HTTP/1.1, abort connection")

///     }

/// });

/// ```

pub fn service_fn<F, R, S>(f: F) -> ServiceFn<F, R>

where

    F: Fn(Request<R>) -> S,

    S: Future,

{

    ServiceFn {

        f,

        _req: PhantomData,

    }

}

/// Service returned by [`service_fn`]

pub struct ServiceFn<F, R> {

    f: F,

    _req: PhantomData<fn(R)>,

}

impl<F, ReqBody, Ret, ResBody, E> Service<Request<ReqBody>> for ServiceFn<F, ReqBody>

where

    F: Fn(Request<ReqBody>) -> Ret,

    ReqBody: Body,

    Ret: Future<Output = Result<Response<ResBody>, E>>,

    E: Into<Box<dyn StdError + Send + Sync>>,

    ResBody: Body,

{

    type Response = crate::Response<ResBody>;

    type Error = E;

    type Future = Ret;

    fn call(&self, req: Request<ReqBody>) -> Self::Future {

        (self.f)(req)

    }

}

impl<F, R> fmt::Debug for ServiceFn<F, R> {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        f.debug_struct("impl Service").finish()

    }

}

impl<F, R> Clone for ServiceFn<F, R>

where

    F: Clone,

{

    fn clone(&self) -> Self {

        ServiceFn {

            f: self.f.clone(),

            _req: PhantomData,

        }

    }

}

impl<F, R> Copy for ServiceFn<F, R> where F: Copy {}