rama-http 0.3.0-rc1

use super::{WriterMode, write_headers_body_flags};
use crate::io::write_http_response;
use crate::{Body, Request, Response, StreamingBody, body::util::BodyExt};
use rama_core::bytes::Bytes;
use rama_core::error::{BoxError, ErrorContext};
use rama_core::extensions::{Extension, ExtensionsRef};
use rama_core::rt::Executor;
use rama_core::telemetry::tracing::{self, Instrument};
use rama_core::{Layer, Service};
use rama_utils::macros::define_inner_service_accessors;
use std::fmt::Debug;
use std::sync::Arc;
use tokio::io::{AsyncWrite, stderr, stdout};
use tokio::sync::mpsc::{Sender, UnboundedSender, channel, unbounded_channel};

/// Layer that applies [`ResponseWriterService`] which prints the http response in std format.
#[derive(Clone)]
pub struct ResponseWriterLayer<W> {
    writer: W,
}

impl<W> Debug for ResponseWriterLayer<W> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ResponseWriterLayer")
            .field("writer", &format_args!("{}", std::any::type_name::<W>()))
            .finish()
    }
}

impl<W> ResponseWriterLayer<W> {
    /// Create a new [`ResponseWriterLayer`] with a custom [`ResponseWriter`].
    pub const fn new(writer: W) -> Self {
        Self { writer }
    }
}

/// A trait for writing http responses.
pub trait ResponseWriter: Send + Sync + 'static {
    /// Write the http response.
    fn write_response(&self, res: Response) -> impl Future<Output = ()> + Send + '_;
}

/// Marker struct to indicate that the response should not be printed.
#[derive(Debug, Clone, Default, Extension)]
#[extension(tags(http))]
#[non_exhaustive]
pub struct DoNotWriteResponse;

impl DoNotWriteResponse {
    /// Create a new [`DoNotWriteResponse`] marker.
    #[must_use]
    pub const fn new() -> Self {
        Self
    }
}

impl ResponseWriterLayer<UnboundedSender<Response>> {
    /// Create a new [`ResponseWriterLayer`] that prints responses to an [`AsyncWrite`]r
    /// over an unbounded channel
    pub fn writer_unbounded<W>(executor: &Executor, mut writer: W, mode: Option<WriterMode>) -> Self
    where
        W: AsyncWrite + Unpin + Send + Sync + 'static,
    {
        let (tx, mut rx) = unbounded_channel();
        let (write_headers, write_body) = write_headers_body_flags(mode);

        let span =
            tracing::trace_root_span!("TrafficWriter::response::unbounded", otel.kind = "consumer");

        executor.spawn_task(
            async move {
                while let Some(res) = rx.recv().await {
                    if let Err(err) =
                        write_http_response(&mut writer, res, write_headers, write_body).await
                    {
                        tracing::error!("failed to write http response to writer: {err:?}")
                    }
                }
            }
            .instrument(span),
        );

        Self { writer: tx }
    }

    /// Create a new [`ResponseWriterLayer`] that prints responses to stdout
    /// over an unbounded channel.
    #[must_use]
    pub fn stdout_unbounded(executor: &Executor, mode: Option<WriterMode>) -> Self {
        Self::writer_unbounded(executor, stdout(), mode)
    }

    /// Create a new [`ResponseWriterLayer`] that prints responses to stderr
    /// over an unbounded channel.
    #[must_use]
    pub fn stderr_unbounded(executor: &Executor, mode: Option<WriterMode>) -> Self {
        Self::writer_unbounded(executor, stderr(), mode)
    }
}

impl ResponseWriterLayer<Sender<Response>> {
    /// Create a new [`ResponseWriterLayer`] that prints responses to an [`AsyncWrite`]r
    /// over a bounded channel with a fixed buffer size.
    pub fn writer<W>(
        executor: &Executor,
        mut writer: W,
        buffer_size: usize,
        mode: Option<WriterMode>,
    ) -> Self
    where
        W: AsyncWrite + Unpin + Send + Sync + 'static,
    {
        let (tx, mut rx) = channel(buffer_size);
        let (write_headers, write_body) = write_headers_body_flags(mode);

        let span =
            tracing::trace_root_span!("TrafficWriter::response::bounded", otel.kind = "consumer");

        executor.spawn_task(
            async move {
                while let Some(res) = rx.recv().await {
                    if let Err(err) =
                        write_http_response(&mut writer, res, write_headers, write_body).await
                    {
                        tracing::error!("failed to write http response to writer: {err:?}")
                    }
                }
            }
            .instrument(span),
        );
        Self { writer: tx }
    }

    /// Create a new [`ResponseWriterLayer`] that prints responses to stdout
    /// over a bounded channel with a fixed buffer size.
    #[must_use]
    pub fn stdout(executor: &Executor, buffer_size: usize, mode: Option<WriterMode>) -> Self {
        Self::writer(executor, stdout(), buffer_size, mode)
    }

    /// Create a new [`ResponseWriterLayer`] that prints responses to stderr
    /// over a bounded channel with a fixed buffer size.
    #[must_use]
    pub fn stderr(executor: &Executor, buffer_size: usize, mode: Option<WriterMode>) -> Self {
        Self::writer(executor, stderr(), buffer_size, mode)
    }
}

impl<S, W: Clone> Layer<S> for ResponseWriterLayer<W> {
    type Service = ResponseWriterService<S, W>;

    fn layer(&self, inner: S) -> Self::Service {
        ResponseWriterService {
            inner,
            writer: self.writer.clone(),
        }
    }

    fn into_layer(self, inner: S) -> Self::Service {
        ResponseWriterService {
            inner,
            writer: self.writer,
        }
    }
}

/// Middleware to print Http request in std format.
///
/// See the [module docs](super) for more details.
#[derive(Clone)]
pub struct ResponseWriterService<S, W> {
    inner: S,
    writer: W,
}

impl<S, W> ResponseWriterService<S, W> {
    /// Create a new [`ResponseWriterService`] with a custom [`ResponseWriter`].
    pub const fn new(writer: W, inner: S) -> Self {
        Self { inner, writer }
    }

    define_inner_service_accessors!();
}

impl<S: Debug, W> Debug for ResponseWriterService<S, W> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ResponseWriterService")
            .field("inner", &self.inner)
            .field("writer", &format_args!("{}", std::any::type_name::<W>()))
            .finish()
    }
}

impl<S> ResponseWriterService<S, UnboundedSender<Response>> {
    /// Create a new [`ResponseWriterService`] that prints responses to an [`AsyncWrite`]r
    /// over an unbounded channel
    pub fn writer_unbounded<W>(
        executor: &Executor,
        writer: W,
        mode: Option<WriterMode>,
        inner: S,
    ) -> Self
    where
        W: AsyncWrite + Unpin + Send + Sync + 'static,
    {
        let layer = ResponseWriterLayer::writer_unbounded(executor, writer, mode);
        layer.into_layer(inner)
    }

    /// Create a new [`ResponseWriterService`] that prints responses to stdout
    /// over an unbounded channel.
    pub fn stdout_unbounded(executor: &Executor, mode: Option<WriterMode>, inner: S) -> Self {
        Self::writer_unbounded(executor, stdout(), mode, inner)
    }

    /// Create a new [`ResponseWriterService`] that prints responses to stderr
    /// over an unbounded channel.
    pub fn stderr_unbounded(executor: &Executor, mode: Option<WriterMode>, inner: S) -> Self {
        Self::writer_unbounded(executor, stderr(), mode, inner)
    }
}

impl<S> ResponseWriterService<S, Sender<Response>> {
    /// Create a new [`ResponseWriterService`] that prints responses to an [`AsyncWrite`]r
    /// over a bounded channel with a fixed buffer size.
    pub fn writer<W>(
        executor: &Executor,
        writer: W,
        buffer_size: usize,
        mode: Option<WriterMode>,
        inner: S,
    ) -> Self
    where
        W: AsyncWrite + Unpin + Send + Sync + 'static,
    {
        let layer = ResponseWriterLayer::writer(executor, writer, buffer_size, mode);
        layer.into_layer(inner)
    }

    /// Create a new [`ResponseWriterService`] that prints responses to stdout
    /// over a bounded channel with a fixed buffer size.
    pub fn stdout(
        executor: &Executor,
        buffer_size: usize,
        mode: Option<WriterMode>,
        inner: S,
    ) -> Self {
        Self::writer(executor, stdout(), buffer_size, mode, inner)
    }

    /// Create a new [`ResponseWriterService`] that prints responses to stderr
    /// over a bounded channel with a fixed buffer size.
    pub fn stderr(
        executor: &Executor,
        buffer_size: usize,
        mode: Option<WriterMode>,
        inner: S,
    ) -> Self {
        Self::writer(executor, stderr(), buffer_size, mode, inner)
    }
}

impl<S, W> ResponseWriterService<S, W> {}

impl<S, W, ReqBody, ResBody> Service<Request<ReqBody>> for ResponseWriterService<S, W>
where
    S: Service<Request<ReqBody>, Output = Response<ResBody>, Error: Into<BoxError>>,
    W: ResponseWriter,
    ReqBody: Send + 'static,
    ResBody: StreamingBody<Data = Bytes, Error: Into<BoxError>> + Send + Sync + 'static,
{
    type Output = Response;
    type Error = BoxError;

    async fn serve(&self, req: Request<ReqBody>) -> Result<Self::Output, Self::Error> {
        let do_not_print_response: Option<Arc<DoNotWriteResponse>> = req.extensions().get_arc();
        let resp = self.inner.serve(req).await.into_box_error()?;
        let resp = if do_not_print_response.is_some() {
            resp.map(Body::new)
        } else {
            let (parts, body) = resp.into_parts();
            let body_bytes = body
                .collect()
                .await
                .context("printer prepare: collect response body")?
                .to_bytes();
            let resp: rama_http_types::Response<Body> =
                Response::from_parts(parts.clone(), Body::from(body_bytes.clone()));
            self.writer.write_response(resp).await;
            Response::from_parts(parts, Body::from(body_bytes))
        };
        Ok(resp)
    }
}

impl ResponseWriter for Sender<Response> {
    async fn write_response(&self, res: Response) {
        if let Err(err) = self.send(res).await {
            tracing::error!("failed to send response to channel: {err:?}")
        }
    }
}

impl ResponseWriter for UnboundedSender<Response> {
    async fn write_response(&self, res: Response) {
        if let Err(err) = self.send(res) {
            tracing::error!("failed to send response to unbounded channel: {err:?}")
        }
    }
}

impl<F, Fut> ResponseWriter for F
where
    F: Fn(Response) -> Fut + Send + Sync + 'static,
    Fut: Future<Output = ()> + Send + 'static,
{
    async fn write_response(&self, res: Response) {
        self(res).await
    }
}