//! Spans reach a REAL OTLP/HTTP receiver: a live server accepting
//! protobuf at /v1/traces, decoded with the official proto types — the
//! exact wire contract any collector speaks.

use std::sync::Arc;

use opentelemetry_proto::tonic::collector::trace::v1::ExportTraceServiceRequest;
use prost::Message;
use tokio::sync::Mutex;

type Received = Arc<Mutex<Vec<ExportTraceServiceRequest>>>;

#[tokio::test(flavor = "multi_thread")]
async fn spans_export_to_a_real_otlp_receiver() {
    let received: Received = Arc::new(Mutex::new(Vec::new()));
    let state = received.clone();
    let app = axum::Router::new()
        .route(
            "/v1/traces",
            axum::routing::post(
                |axum::extract::State(state): axum::extract::State<Received>,
                 body: axum::body::Bytes| async move {
                    let request =
                        ExportTraceServiceRequest::decode(body.as_ref()).expect("otlp protobuf");
                    state.lock().await.push(request);
                    // An empty ExportTraceServiceResponse.
                    (
                        [("content-type", "application/x-protobuf")],
                        Vec::<u8>::new(),
                    )
                },
            ),
        )
        .with_state(state);
    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
    let endpoint = format!("http://{}", listener.local_addr().unwrap());
    tokio::spawn(async move {
        axum::serve(listener, app).await.unwrap();
    });

    let guard = cm_telemetry::init("clawmates-test", Some(&endpoint)).expect("init");

    {
        let span = tracing::info_span!("approval_decision", approval_id = "ap_123");
        let _entered = span.enter();
        tracing::info!("decided");
    }
    guard.flush();

    // Find our span among everything exported.
    let requests = received.lock().await;
    assert!(!requests.is_empty(), "no OTLP export arrived");
    let mut span_names = Vec::new();
    let mut service_names = Vec::new();
    for request in requests.iter() {
        for resource in &request.resource_spans {
            if let Some(res) = &resource.resource {
                for attr in &res.attributes {
                    if attr.key == "service.name" {
                        if let Some(value) = &attr.value {
                            service_names.push(format!("{value:?}"));
                        }
                    }
                }
            }
            for scope in &resource.scope_spans {
                for span in &scope.spans {
                    span_names.push(span.name.clone());
                }
            }
        }
    }
    assert!(
        span_names.iter().any(|name| name == "approval_decision"),
        "spans: {span_names:?}"
    );
    assert!(
        service_names.iter().any(|s| s.contains("clawmates-test")),
        "services: {service_names:?}"
    );
}