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receiver.go
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package receiver
import (
"encoding/json"
"errors"
"reflect"
"github.com/Postcord/rest"
"github.com/nats-io/nats.go"
"github.com/sirupsen/logrus"
)
type EventHandler interface{}
// Receiver is a client to interface with the Chator NATS Discord interface
type Receiver struct {
conn *nats.Conn
session *rest.Client
handlers map[string][]EventHandler
log *logrus.Logger
serviceName string
}
// Config contains the configuration options for the Receiver
type Config struct {
NatsAddr string
Token string
Logger *logrus.Logger
Client *rest.Client
ServiceName string
}
// NewReceiver Creates a new Discord NATS receiver
func New(conf *Config) (*Receiver, error) {
if conf.Token == "" && conf.Client == nil {
return nil, errors.New("no valid token provided")
}
if conf.NatsAddr == "" {
conf.NatsAddr = nats.DefaultURL
}
if conf.Logger == nil {
conf.Logger = logrus.New()
conf.Logger.SetLevel(logrus.DebugLevel)
conf.Logger.SetFormatter(&logrus.TextFormatter{
ForceColors: true,
DisableTimestamp: false,
FullTimestamp: true,
TimestampFormat: "",
})
}
var err error
r := &Receiver{
handlers: make(map[string][]EventHandler),
}
r.conn, err = nats.Connect(conf.NatsAddr)
if err != nil {
return nil, err
}
r.log = conf.Logger
// TODO: Add redis cache interface
if conf.Client == nil {
r.session = rest.New(&rest.Config{
Authorization: "Bot " + conf.Token,
Ratelimiter: rest.NewMemoryRatelimiter(&rest.MemoryConf{
MaxRetries: 3,
}),
UserAgent: "Postcord/1.0",
})
if err != nil {
return nil, err
}
} else {
r.session = conf.Client
}
// r.session = disgord.New(disgord.Config{
// BotToken: conf.Token,
// Logger: conf.Logger,
// })
return r, nil
}
func (r *Receiver) Start() {
for k := range r.handlers {
r.log.Infof("Subscribing to %s", k)
if r.serviceName != "" {
r.conn.QueueSubscribe(k, r.serviceName, r.listener)
} else {
r.conn.Subscribe(k, r.listener)
}
}
}
func (r *Receiver) Close() {
r.conn.Close()
}
// On registers an event listener
func (r *Receiver) On(sub string, handler EventHandler) {
if _, ok := r.handlers[sub]; ok {
r.handlers[sub] = append(r.handlers[sub], handler)
} else {
r.handlers[sub] = []EventHandler{handler}
}
}
func (r *Receiver) listener(m *nats.Msg) {
defer func() {
if rec := recover(); rec != nil {
r.log.Errorf("panic while calling handler for %s", m.Subject)
}
}()
r.log.Debugf("Event received: %s", m.Subject)
handlers := r.handlers[m.Subject]
for _, h := range handlers {
x := reflect.TypeOf(h)
numIn := x.NumIn() //Count inbound parameters
numOut := x.NumOut() //Count outbounding parameters
if numIn != 2 || numOut != 0 {
r.log.Warn("Invalid function signature for event ", m.Subject)
return
}
// This is the object to deserialize into
inType := x.In(1)
typePtr := reflect.New(inType.Elem())
obj := typePtr.Interface()
err := json.Unmarshal(m.Data, obj)
if err != nil {
r.log.Warn("Failed to unmarshal ", m.Subject, " into ", obj, ": ", err.Error())
return
}
f := reflect.ValueOf(h)
f.Call([]reflect.Value{reflect.ValueOf(r.session), typePtr})
}
}