feat: Website (#15)

Add a basic website that shows the current flutgrid state
Co-authored-by: Noa Aarts <noa@voorwaarts.nl>

src/webapi.rs

@@ -0,0 +1,96 @@
+use std::{net::SocketAddr, process::exit, sync::Arc};
+
+use axum::{
+    extract::{ConnectInfo, Query, State},
+    http::{self, HeaderMap, HeaderValue},
+    response::IntoResponse,
+    routing::any,
+    Router,
+};
+use axum_extra::TypedHeader;
+use axum_streams::StreamBodyAs;
+use futures::{never::Never, stream::repeat_with, Stream};
+use serde::Deserialize;
+use tokio::net::TcpListener;
+use tower_http::trace::{DefaultMakeSpan, TraceLayer};
+
+use crate::{
+    config::{WEB_HOST, WEB_UPDATE_INTERVAL},
+    grid,
+    stream::Multipart,
+    AsyncResult,
+};
+
+#[derive(Clone)]
+pub struct WebApiContext {
+    pub grids: Arc<[grid::Flut<u32>]>,
+}
+
+pub async fn serve(ctx: WebApiContext) -> AsyncResult<Never> {
+    let app = Router::new()
+        .route("/imgstream", any(image_stream))
+        .with_state(ctx)
+        // logging middleware
+        .layer(
+            TraceLayer::new_for_http()
+                .make_span_with(DefaultMakeSpan::default().include_headers(true)),
+        );
+
+    // run it with hyper
+    let Ok(listener) = TcpListener::bind(WEB_HOST).await else {
+        tracing::error!(
+            "Was unable to bind to {WEB_HOST}, please check if a different process is bound"
+        );
+        exit(1);
+    };
+
+    tracing::debug!("listening on {}", listener.local_addr()?);
+
+    axum::serve(
+        listener,
+        app.into_make_service_with_connect_info::<SocketAddr>(),
+    )
+    .await?;
+
+    Err("Web api exited".into())
+}
+
+#[derive(Debug, Deserialize)]
+struct CanvasQuery {
+    canvas: u8,
+}
+
+fn make_image_stream(
+    ctx: WebApiContext,
+    canvas: u8,
+) -> impl Stream<Item = Result<Vec<u8>, axum::Error>> {
+    use tokio_stream::StreamExt;
+    let mut buf = Vec::new();
+    repeat_with(move || {
+        buf.clear();
+        buf.extend_from_slice(&ctx.grids[canvas as usize].read_jpg_buffer());
+        Ok(buf.clone())
+    })
+    .throttle(WEB_UPDATE_INTERVAL)
+}
+
+async fn image_stream(
+    user_agent: Option<TypedHeader<headers::UserAgent>>,
+    ConnectInfo(addr): ConnectInfo<SocketAddr>,
+    State(ctx): State<WebApiContext>,
+    Query(CanvasQuery { canvas }): Query<CanvasQuery>,
+) -> impl IntoResponse {
+    let user_agent = if let Some(TypedHeader(user_agent)) = user_agent {
+        user_agent.to_string()
+    } else {
+        String::from("Unknown browser")
+    };
+    tracing::info!("`{user_agent}` at {addr} connected.");
+    let mut headers = HeaderMap::new();
+    headers.insert(
+        http::header::CONTENT_TYPE,
+        HeaderValue::from_static("image/jpeg"),
+    );
+
+    StreamBodyAs::new(Multipart::new(10, headers), make_image_stream(ctx, canvas))
+}