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use std::{borrow::Cow, convert::Infallible};

use bytes::{Bytes, BytesMut};
use http::{header::CONTENT_TYPE, HeaderValue, StatusCode};

use crate::{
    body::ResponseBody, either::Either, error::BoxError, media_type::MediaType, response::Response,
    response_error::ResponseError,
};

pub trait IntoResponse {
    type Error: ResponseError;

    fn into_response(self) -> Result<Response, Self::Error>;
}

impl<B> IntoResponse for Response<B>
where
    B: http_body::Body<Data = Bytes> + Send + 'static,
    B::Error: Into<BoxError>,
{
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        Ok(self.map(ResponseBody::new))
    }
}

impl IntoResponse for http::response::Parts {
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        Ok(Response::from_parts(self, ResponseBody::empty()))
    }
}

impl IntoResponse for ResponseBody {
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        Ok(Response::new(self))
    }
}

impl IntoResponse for () {
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        ResponseBody::empty().into_response()
    }
}

impl IntoResponse for StatusCode {
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        let mut response = ().into_response()?;
        *response.status_mut() = self;
        Ok(response)
    }
}

impl IntoResponse for Infallible {
    type Error = Infallible;

    fn into_response(self) -> Result<Response, Self::Error> {
        match self {}
    }
}

macro_rules! some_impl {
    ($ty:ty; $($desc:tt)+) => {
        impl $($desc)+
        {
            type Error = Infallible;

            fn into_response(self) -> Result<Response, Self::Error> {
                let mut response = Response::new(self.into());

                response
                    .headers_mut()
                    .insert(CONTENT_TYPE, HeaderValue::from_static(<$ty as MediaType>::MEDIA_TYPE));

                Ok(response)
            }
        }
    };
}

some_impl!(String; IntoResponse for &'static str);
some_impl!(String; IntoResponse for Cow<'static, str>);
some_impl!(String; IntoResponse for String);
some_impl!(String; IntoResponse for Box<str>);

some_impl!(Vec<u8>; IntoResponse for &'static [u8]);
some_impl!(Vec<u8>; IntoResponse for Cow<'static, [u8]>);
some_impl!(Vec<u8>; IntoResponse for Vec<u8>);
some_impl!(Vec<u8>; IntoResponse for Bytes);
some_impl!(Vec<u8>; IntoResponse for BytesMut);
some_impl!(Vec<u8>; IntoResponse for Box<[u8]>);

some_impl!([u8; N]; <const N: usize> IntoResponse for [u8; N]);
some_impl!([u8; N]; <const N: usize> IntoResponse for &'static [u8; N]);

impl<T, E> IntoResponse for Result<T, E>
where
    T: IntoResponse,
    E: ResponseError,
{
    type Error = Either<T::Error, E>;

    fn into_response(self) -> Result<Response, Self::Error> {
        match self {
            Ok(t) => t.into_response().map_err(Either::Left),
            Err(e) => Err(Either::Right(e)),
        }
    }
}