feat: WIP

transport.go

@@ -0,0 +1,88 @@
+package nats_transport
+
+import (
+	"fmt"
+	"github.com/golang/protobuf/proto"
+	"github.com/nats-io/nats.go"
+	"net/http"
+	"time"
+)
+
+// SubjectResolveFunc resolves the NATS subject (based on http.Request struct)
+type SubjectResolveFunc func(r *http.Request) string
+
+// ModifyRequestHookFunc is the hook to modify Request struct (protobuf)
+type ModifyRequestHookFunc = func(req *http.Request, r *Request)
+
+type NatsTransport struct {
+	// NatsConnection connection to NATS server
+	NatsConnection *nats.Conn
+
+	// Subject NATS subject to push wrapped HTTP request on
+	Subject string
+
+	// SubjectResolver used only if Subject is not specified
+	SubjectResolver SubjectResolveFunc
+
+	// ModifyRequestHook calls after Request struct parsed from HTTP and before sent to NATS
+	ModifyRequestHook ModifyRequestHookFunc
+
+	// Timeout NATS request timeout
+	Timeout time.Duration
+}
+
+func (nt NatsTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	request := NewRequest()
+
+	if err := request.FromHTTP(r); err != nil {
+		return nil, fmt.Errorf("nats_transport: cannot parse HTTP request: %v", err)
+	}
+
+	// call modify request hook
+	if nt.ModifyRequestHook != nil {
+		nt.ModifyRequestHook(r, request)
+	}
+
+	// Serialize the request.
+	requestBytes, err := proto.Marshal(request)
+	if err != nil {
+		return nil, fmt.Errorf("nats_transport: cannot serialize request")
+	}
+
+	// get the outgoing NATS subject
+	natsSubject := nt.Subject
+	if natsSubject == "" {
+		natsSubject = nt.SubjectResolver(r)
+	}
+	if natsSubject == "" {
+		return nil, fmt.Errorf("nats_transport: cannot detect NATS subject")
+	}
+
+	// Send Request to NATS server
+	msg, err := nt.NatsConnection.Request(
+		natsSubject,
+		requestBytes,
+		nt.Timeout,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("nats_transport: cannot send NATS request")
+	}
+
+	// Get Response object from NATS message
+	response := NewResponse()
+	if err := response.ReadFrom(msg.Data); err != nil {
+		return nil, fmt.Errorf("nats_transport: %v", err)
+	}
+
+	if response.Error != "" {
+		return nil, fmt.Errorf("nats_transport: %s", response.Error)
+	}
+
+	// prepare HTTP response
+	httpResponse, err := response.ToHTTPResponse(r)
+	if err != nil {
+		return nil, fmt.Errorf("nats_transport: %v", err)
+	}
+
+	return httpResponse, nil
+}