oc-lib/tools/nats_caller.go

package tools

import (
	"encoding/json"
	"strings"

	"github.com/nats-io/nats.go"
)

// NATS Method Enum defines the different methods that can be used to interact with the NATS server
type NATSMethod int

const (
	REMOVE NATSMethod = iota
	CREATE
)

// NameToMethod returns the NATSMethod enum value from a string
func NameToMethod(name string) NATSMethod {
	for _, v := range [...]NATSMethod{REMOVE, CREATE} {
		if strings.Contains(strings.ToLower(v.String()), strings.ToLower(name)) {
			return v
		}
	}
	return -1
}

// GenerateKey generates a key for the NATSMethod usefull for standard key based on data name & method
func (d NATSMethod) GenerateKey(name string) string {
	return name + "_" + d.String()
}

// String returns the string of the enum
func (d NATSMethod) String() string {
	return [...]string{"remove", "create", "discovery"}[d]
}

type natsCaller struct{}

// NewNATSCaller creates a new instance of the NATS Caller
func NewNATSCaller() *natsCaller {
	return &natsCaller{}
}

// SetNATSPub sets a message to the NATS server
func (o *natsCaller) SetNATSPub(dataName string, method NATSMethod, data interface{}) string {
	if GetConfig().NATSUrl == "" {
		return " -> NATS_SERVER is not set"
	}
	nc, err := nats.Connect(GetConfig().NATSUrl)
	if err != nil {
		return " -> Could not reach NATS server : " + err.Error()
	}
	defer nc.Close()
	js, err := json.Marshal(data)
	if err != nil {
		return " -> " + err.Error()
	}
	err = nc.Publish(method.GenerateKey(dataName), js) // Publish the message on the NATS server with a channel name based on the data name (or whatever start) and the method
	if err != nil {
		return " -> " + err.Error() // Return an error if the message could not be published
	}
	return ""
}