Save subscribers, add load and save

cmd/hubserver/main.go

@@ -1,17 +1,21 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"math/rand"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
+	"strings"
 )
 
 const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
 
-func RandStringBytes(n int) string {
+func randStringBytes(n int) string {
 	b := make([]byte, n)
 	for i := range b {
 		b[i] = letterBytes[rand.Intn(len(letterBytes))]
@@ -19,8 +23,13 @@ func RandStringBytes(n int) string {
 	return string(b)
 }
 
+type Subscriber struct {
+	Callback     string
+	LeaseSeconds int64
+}
+
 type subscriptionHandler struct {
-	Subscribers []string
+	Subscribers map[string][]Subscriber
 }
 
 func (handler *subscriptionHandler) handlePublish(w http.ResponseWriter, r *http.Request) error {
@@ -34,11 +43,12 @@ func (handler *subscriptionHandler) handleSubscription(w http.ResponseWriter, r
 	callback := r.Form.Get("hub.callback")
 	topic := r.Form.Get("hub.topic")
 	leaseSecondsStr := r.Form.Get("hub.lease_seconds")
-	_, err := strconv.ParseInt(leaseSecondsStr, 10, 64)
+	leaseSeconds, err := strconv.ParseInt(leaseSecondsStr, 10, 64)
 	if leaseSecondsStr != "" && err != nil {
 		http.Error(w, "hub.lease_seconds is used, but not valid", 400)
 		return nil
 	}
+
 	//secret := r.Form.Get("hub.secret")
 	callbackURL, err := url.Parse(callback)
 	if err != nil {
@@ -56,25 +66,49 @@ func (handler *subscriptionHandler) handleSubscription(w http.ResponseWriter, r
 	go func() {
 		client := http.Client{}
 
+		ourChallenge := randStringBytes(12)
+
 		validationURL := callbackURL
 		q := validationURL.Query()
 		q.Add("hub.mode", "subscribe")
 		q.Add("hub.topic", topicURL.String())
-		q.Add("hub.challenge", RandStringBytes(12))
+		q.Add("hub.challenge", ourChallenge)
 		q.Add("hub.lease_seconds", leaseSecondsStr)
 		validationURL.RawQuery = q.Encode()
 
 		log.Println(validationURL)
 
 		req, err := http.NewRequest(http.MethodGet, callbackURL.String(), nil)
+		if err != nil {
+			log.Println(err)
+			return
+		}
 		res, err := client.Do(req)
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		defer res.Body.Close()
 
-		log.Println(res, err)
+		body, err := ioutil.ReadAll(res.Body)
+		if err != nil {
+			log.Println(err)
+		}
+
+		if strings.Contains(string(body), ourChallenge) {
+			// challenge accepted
+			handler.addSubscriberCallback(topicURL.String(), Subscriber{callbackURL.String(), leaseSeconds})
+		}
 	}()
 
 	return nil
 }
 
+func (handler *subscriptionHandler) addSubscriberCallback(topic string, subscriber Subscriber) {
+	handler.Subscribers[topic] = append(handler.Subscribers[topic], subscriber)
+	handler.save()
+}
+
 func (handler *subscriptionHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if r.Header.Get("Content-Type") != "application/x-www-form-urlencoded" {
 		http.Error(w, "Bad Request", 400)
@@ -102,10 +136,32 @@ func (handler *subscriptionHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
 	}
 }
 
+func (handler *subscriptionHandler) load() error {
+	file, err := os.Open("./subscription.json")
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	dec := json.NewDecoder(file)
+	dec.Decode(handler.Subscribers)
+	return nil
+}
+
+func (handler *subscriptionHandler) save() error {
+	file, err := os.Create("./subscription.json")
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	dec := json.NewEncoder(file)
+	dec.SetIndent("", "    ")
+	dec.Encode(handler.Subscribers)
+	return nil
+}
+
 func main() {
 	handler := &subscriptionHandler{}
-	//handler.Subscribers
-
+	handler.load()
 	http.Handle("/", handler)
 	log.Fatal(http.ListenAndServe(":80", nil))
 }