rama-http 0.2.0

use std::fmt;

use crate::dep::http_body::Body;
use crate::dep::http_body_util::{BodyExt, Empty, combinators::UnsyncBoxBody};
use crate::headers::encoding::{AcceptEncoding, SupportedEncodings};
use crate::layer::{
    decompression::DecompressionBody,
    decompression::body::BodyInner,
    util::compression::{CompressionLevel, WrapBody},
};
use crate::{HeaderValue, Request, Response, StatusCode, header};
use bytes::Buf;
use rama_core::error::BoxError;
use rama_core::{Context, Service};
use rama_utils::macros::define_inner_service_accessors;

/// Decompresses request bodies and calls its underlying service.
///
/// Transparently decompresses request bodies based on the `Content-Encoding` header.
/// When the encoding in the `Content-Encoding` header is not accepted an `Unsupported Media Type`
/// status code will be returned with the accepted encodings in the `Accept-Encoding` header.
///
/// Enabling pass-through of unaccepted encodings will not return an `Unsupported Media Type` but
/// will call the underlying service with the unmodified request if the encoding is not supported.
/// This is disabled by default.
///
/// See the [module docs](crate::layer::decompression) for more details.
pub struct RequestDecompression<S> {
    pub(super) inner: S,
    pub(super) accept: AcceptEncoding,
    pub(super) pass_through_unaccepted: bool,
}

impl<S: fmt::Debug> fmt::Debug for RequestDecompression<S> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("RequestDecompression")
            .field("inner", &self.inner)
            .field("accept", &self.accept)
            .field("pass_through_unaccepted", &self.pass_through_unaccepted)
            .finish()
    }
}

impl<S: Clone> Clone for RequestDecompression<S> {
    fn clone(&self) -> Self {
        RequestDecompression {
            inner: self.inner.clone(),
            accept: self.accept,
            pass_through_unaccepted: self.pass_through_unaccepted,
        }
    }
}

impl<S, State, ReqBody, ResBody, D> Service<State, Request<ReqBody>> for RequestDecompression<S>
where
    S: Service<
            State,
            Request<DecompressionBody<ReqBody>>,
            Response = Response<ResBody>,
            Error: Into<BoxError>,
        >,
    State: Clone + Send + Sync + 'static,
    ReqBody: Body + Send + 'static,
    ResBody: Body<Data = D, Error: Into<BoxError>> + Send + 'static,
    D: Buf + 'static,
{
    type Response = Response<UnsyncBoxBody<D, BoxError>>;
    type Error = BoxError;

    async fn serve(
        &self,
        ctx: Context<State>,
        req: Request<ReqBody>,
    ) -> Result<Self::Response, Self::Error> {
        let (mut parts, body) = req.into_parts();

        let body =
            if let header::Entry::Occupied(entry) = parts.headers.entry(header::CONTENT_ENCODING) {
                match entry.get().as_bytes() {
                    b"gzip" if self.accept.gzip() => {
                        entry.remove();
                        parts.headers.remove(header::CONTENT_LENGTH);
                        BodyInner::gzip(WrapBody::new(body, CompressionLevel::default()))
                    }
                    b"deflate" if self.accept.deflate() => {
                        entry.remove();
                        parts.headers.remove(header::CONTENT_LENGTH);
                        BodyInner::deflate(WrapBody::new(body, CompressionLevel::default()))
                    }
                    b"br" if self.accept.br() => {
                        entry.remove();
                        parts.headers.remove(header::CONTENT_LENGTH);
                        BodyInner::brotli(WrapBody::new(body, CompressionLevel::default()))
                    }
                    b"zstd" if self.accept.zstd() => {
                        entry.remove();
                        parts.headers.remove(header::CONTENT_LENGTH);
                        BodyInner::zstd(WrapBody::new(body, CompressionLevel::default()))
                    }
                    b"identity" => BodyInner::identity(body),
                    _ if self.pass_through_unaccepted => BodyInner::identity(body),
                    _ => return unsupported_encoding(self.accept).await,
                }
            } else {
                BodyInner::identity(body)
            };
        let body = DecompressionBody::new(body);
        let req = Request::from_parts(parts, body);
        self.inner
            .serve(ctx, req)
            .await
            .map(|res| res.map(|body| body.map_err(Into::into).boxed_unsync()))
            .map_err(Into::into)
    }
}

async fn unsupported_encoding<D>(
    accept: AcceptEncoding,
) -> Result<Response<UnsyncBoxBody<D, BoxError>>, BoxError>
where
    D: Buf + 'static,
{
    let res = Response::builder()
        .header(
            header::ACCEPT_ENCODING,
            accept
                .maybe_to_header_value()
                .unwrap_or(HeaderValue::from_static("identity")),
        )
        .status(StatusCode::UNSUPPORTED_MEDIA_TYPE)
        .body(Empty::new().map_err(Into::into).boxed_unsync())
        .unwrap();
    Ok(res)
}

impl<S> RequestDecompression<S> {
    /// Creates a new `RequestDecompression` wrapping the `service`.
    pub fn new(service: S) -> Self {
        Self {
            inner: service,
            accept: AcceptEncoding::default(),
            pass_through_unaccepted: false,
        }
    }

    define_inner_service_accessors!();

    /// Passes through the request even when the encoding is not supported.
    ///
    /// By default pass-through is disabled.
    pub fn pass_through_unaccepted(mut self, enabled: bool) -> Self {
        self.pass_through_unaccepted = enabled;
        self
    }

    /// Passes through the request even when the encoding is not supported.
    ///
    /// By default pass-through is disabled.
    pub fn set_pass_through_unaccepted(&mut self, enabled: bool) -> &mut Self {
        self.pass_through_unaccepted = enabled;
        self
    }

    /// Sets whether to support gzip encoding.
    pub fn gzip(mut self, enable: bool) -> Self {
        self.accept.set_gzip(enable);
        self
    }

    /// Sets whether to support gzip encoding.
    pub fn set_gzip(&mut self, enable: bool) -> &mut Self {
        self.accept.set_gzip(enable);
        self
    }

    /// Sets whether to support Deflate encoding.
    pub fn deflate(mut self, enable: bool) -> Self {
        self.accept.set_deflate(enable);
        self
    }

    /// Sets whether to support Deflate encoding.
    pub fn set_deflate(&mut self, enable: bool) -> &mut Self {
        self.accept.set_deflate(enable);
        self
    }

    /// Sets whether to support Brotli encoding.
    pub fn br(mut self, enable: bool) -> Self {
        self.accept.set_br(enable);
        self
    }

    /// Sets whether to support Brotli encoding.
    pub fn set_br(&mut self, enable: bool) -> &mut Self {
        self.accept.set_br(enable);
        self
    }

    /// Sets whether to support Zstd encoding.
    pub fn zstd(mut self, enable: bool) -> Self {
        self.accept.set_zstd(enable);
        self
    }

    /// Sets whether to support Zstd encoding.
    pub fn set_zstd(&mut self, enable: bool) -> &mut Self {
        self.accept.set_zstd(enable);
        self
    }
}