//! `DatastreamSink` — the cluster-side consumer of [`DatastreamFrame`] messages.
//!
//! This is the counterpart to [`ClusterFrameSink`](super::emit::ClusterFrameSink):
//! a node ships its ordered telemetry as `DatastreamFrame` actor messages over the
//! regular swactor transport, and this actor — registered under a well-known name
//! on the collector (e.g. the orchestrator) — receives them, decodes each back
//! into a `(StreamId, Frame)` delivery, and hands it to a caller-supplied fold.
//!
//! It deliberately knows nothing about any view layer. The actor owns an opaque
//! callback so binaries can wire the decoded deliveries into whichever fold they
//! need. Malformed payloads are dropped silently — the same best-effort tolerance
//! the UDP ingest had.

use swactor::actor::ActorInterface;
use swactor::runtime::Ctx;

use super::frame::{Frame, StreamId};
use super::wire::{DatastreamFrame, decode_delivery};

/// Receives [`DatastreamFrame`] cluster messages and folds each decoded delivery
/// through `on_frame`. Spawn it, then publish its address under
/// [`DATASTREAM_SINK_NAME`] so emitters can resolve and ship to it.
pub struct DatastreamSink {
    on_frame: Box<dyn FnMut(StreamId, Frame) + Send>,
}

/// The cluster name a [`DatastreamSink`] is published under. Emitters resolve
/// this to fill their `ClusterFrameSink` destination.
pub const DATASTREAM_SINK_NAME: &str = "datastream-sink";

impl DatastreamSink {
    /// Build a sink that folds every decoded delivery through `on_frame`.
    pub fn new(on_frame: impl FnMut(StreamId, Frame) + Send + 'static) -> Self {
        Self {
            on_frame: Box::new(on_frame),
        }
    }
}

impl ActorInterface for DatastreamSink {
    type Incoming = DatastreamFrame;
    type Response = ();

    fn handle(&mut self, _ctx: &Ctx, msg: DatastreamFrame) {
        // Best-effort: a malformed datagram is dropped, never panics the sink.
        if let Ok((stream, frame)) = decode_delivery(&msg.payload) {
            (self.on_frame)(stream, frame);
        }
    }
}