add simple NATS client

nats-client.go

@@ -0,0 +1,113 @@
+package showbridge
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/jwetzell/showbridge-go/internal/processing"
+	"github.com/nats-io/nats.go"
+)
+
+type NATSClient struct {
+	config  ModuleConfig
+	router  *Router
+	URL     string
+	Subject string
+	client  *nats.Conn
+}
+
+func init() {
+	RegisterModule(ModuleRegistration{
+		Type: "net.nats.client",
+		New: func(config ModuleConfig) (Module, error) {
+			params := config.Params
+			url, ok := params["url"]
+
+			if !ok {
+				return nil, fmt.Errorf("net.nats.client requires a url parameter")
+			}
+
+			urlString, ok := url.(string)
+
+			if !ok {
+				return nil, fmt.Errorf("net.nats.client url must be string")
+			}
+
+			subject, ok := params["subject"]
+
+			if !ok {
+				return nil, fmt.Errorf("net.nats.client requires a subject parameter")
+			}
+
+			subjectString, ok := subject.(string)
+
+			if !ok {
+				return nil, fmt.Errorf("net.nats.client subject must be string")
+			}
+
+			return &NATSClient{config: config, URL: urlString, Subject: subjectString}, nil
+		},
+	})
+}
+
+func (nc *NATSClient) Id() string {
+	return nc.config.Id
+}
+
+func (nc *NATSClient) Type() string {
+	return nc.config.Type
+}
+
+func (nc *NATSClient) RegisterRouter(router *Router) {
+	nc.router = router
+}
+
+func (nc *NATSClient) Run() error {
+	client, err := nats.Connect(nc.URL, nats.RetryOnFailedConnect(true))
+
+	if err != nil {
+		return err
+	}
+
+	nc.client = client
+
+	defer client.Drain()
+	defer client.Close()
+
+	sub, err := nc.client.Subscribe(nc.Subject, func(msg *nats.Msg) {
+		if nc.router != nil {
+			nc.router.HandleInput(nc.config.Id, msg)
+		}
+	})
+
+	if err != nil {
+		return err
+	}
+
+	defer sub.Unsubscribe()
+
+	<-nc.router.Context.Done()
+	slog.Debug("router context done in module", "id", nc.config.Id)
+	return nil
+}
+
+func (nc *NATSClient) Output(payload any) error {
+
+	payloadMessage, ok := payload.(processing.NATSMessage)
+
+	if !ok {
+		return fmt.Errorf("net.nats.client is only able to output NATSMessage")
+	}
+
+	if nc.client == nil {
+		return fmt.Errorf("net.nats.client client is not setup")
+	}
+
+	if !nc.client.IsConnected() {
+		return fmt.Errorf("net.nats.client is not connected")
+	}
+
+	err := nc.client.Publish(payloadMessage.Subject, payloadMessage.Payload)
+
+	return err
+}