chore: move the go code into a subfolder

apps/api/internal/integration/sink/subscription.go

@@ -0,0 +1,90 @@
+//go:build integration
+
+package sink
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"sync/atomic"
+
+	"github.com/gorilla/websocket"
+	"github.com/zitadel/logging"
+)
+
+// Request is a message forwarded from the handler to [Subscription]s.
+type Request struct {
+	Header http.Header
+	Body   json.RawMessage
+}
+
+// Subscription is a websocket client to which [Request]s are forwarded by the server.
+type Subscription struct {
+	conn       *websocket.Conn
+	closed     atomic.Bool
+	reqChannel chan *Request
+}
+
+// Subscribe to a channel.
+// The subscription forwards all requests it received on the channel's
+// handler, after Subscribe has returned.
+// Multiple subscription may be active on a single channel.
+// Each request is always forwarded to each Subscription.
+// Close must be called to cleanup up the Subscription's channel and go routine.
+func Subscribe(ctx context.Context, ch Channel) *Subscription {
+	u := url.URL{
+		Scheme: "ws",
+		Host:   listenAddr,
+		Path:   subscribePath(ch),
+	}
+	conn, resp, err := websocket.DefaultDialer.DialContext(ctx, u.String(), nil)
+	if err != nil {
+		if resp != nil {
+			defer resp.Body.Close()
+			body, _ := io.ReadAll(resp.Body)
+			err = fmt.Errorf("subscribe: %w, status: %s, body: %s", err, resp.Status, body)
+		}
+		panic(err)
+	}
+
+	sub := &Subscription{
+		conn:       conn,
+		reqChannel: make(chan *Request, 10),
+	}
+	go sub.readToChan()
+	return sub
+}
+
+func (s *Subscription) readToChan() {
+	for {
+		if s.closed.Load() {
+			break
+		}
+		req := new(Request)
+		if err := s.conn.ReadJSON(req); err != nil {
+			opErr := new(net.OpError)
+			if errors.As(err, &opErr) {
+				break
+			}
+			logging.WithError(err).Error("subscription read")
+			break
+		}
+		s.reqChannel <- req
+	}
+	close(s.reqChannel)
+}
+
+// Recv returns the channel over which [Request]s are send.
+func (s *Subscription) Recv() <-chan *Request {
+	return s.reqChannel
+}
+
+func (s *Subscription) Close() error {
+	s.closed.Store(true)
+	return s.conn.Close()
+}