service backend

api/pkg/messaging/internal/natsb/broker.go

@@ -0,0 +1,113 @@
+package natsb
+
+import (
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/nats-io/nats.go"
+	"github.com/tech/sendico/pkg/merrors"
+	nc "github.com/tech/sendico/pkg/messaging/internal/natsb/config"
+	"github.com/tech/sendico/pkg/mlogger"
+	"go.uber.org/zap"
+)
+
+type natsSubscriotions = map[string]*TopicSubscription
+
+type NatsBroker struct {
+	nc        *nats.Conn
+	logger    *zap.Logger
+	topicSubs natsSubscriotions
+	mu        sync.Mutex
+}
+
+type envConfig struct {
+	User, Password, Host string
+	Port                 int
+}
+
+// loadEnv gathers and validates connection details from environment variables
+// listed in the Settings struct. Invalid or missing values surface as a typed
+// InvalidArgument error so callers can decide how to handle them.
+func loadEnv(settings *nc.Settings, l *zap.Logger) (*envConfig, error) {
+	get := func(key, label string) (string, error) {
+		if v := os.Getenv(key); v != "" {
+			return v, nil
+		}
+		l.Error(fmt.Sprintf("NATS %s not found in environment", label), zap.String("env_var", key))
+		return "", merrors.InvalidArgument(fmt.Sprintf("NATS %s not found in environment variable: %s", label, key))
+	}
+
+	user, err := get(settings.UsernameEnv, "user name")
+	if err != nil {
+		return nil, err
+	}
+
+	password, err := get(settings.PasswordEnv, "password")
+	if err != nil {
+		return nil, err
+	}
+
+	host, err := get(settings.HostEnv, "host")
+	if err != nil {
+		return nil, err
+	}
+
+	portStr, err := get(settings.PortEnv, "port")
+	if err != nil {
+		return nil, err
+	}
+
+	port, err := strconv.Atoi(portStr)
+	if err != nil || port <= 0 || port > 65535 {
+		l.Error("Invalid NATS port value", zap.String("port", portStr))
+		return nil, merrors.InvalidArgument("Invalid NATS port: " + portStr)
+	}
+
+	return &envConfig{
+		User:     user,
+		Password: password,
+		Host:     host,
+		Port:     port,
+	}, nil
+}
+
+func NewNatsBroker(logger mlogger.Logger, settings *nc.Settings) (*NatsBroker, error) {
+	l := logger.Named("broker")
+	// Helper function to get environment variables
+	cfg, err := loadEnv(settings, l)
+	if err != nil {
+		return nil, err
+	}
+
+	u := &url.URL{
+		Scheme: "nats",
+		Host:   net.JoinHostPort(cfg.Host, strconv.Itoa(cfg.Port)),
+	}
+	natsURL := u.String()
+
+	opts := []nats.Option{
+		nats.Name(settings.NATSName),
+		nats.MaxReconnects(settings.MaxReconnects),
+		nats.ReconnectWait(time.Duration(settings.ReconnectWait) * time.Second),
+		nats.UserInfo(cfg.User, cfg.Password),
+	}
+
+	res := &NatsBroker{
+		logger:    l.Named("nats"),
+		topicSubs: natsSubscriotions{},
+	}
+
+	if res.nc, err = nats.Connect(natsURL, opts...); err != nil {
+		l.Error("Failed to connect to NATS", zap.String("url", natsURL), zap.Error(err))
+		return nil, err
+	}
+
+	logger.Info("Connected to NATS", zap.String("broker", settings.NATSName),
+		zap.String("url", fmt.Sprintf("nats://%s@%s", cfg.User, net.JoinHostPort(cfg.Host, strconv.Itoa(cfg.Port)))))
+	return res, nil
+}