Template streaming

api.go

@@ -4,6 +4,7 @@ import "encoding/json"
 import "fmt"
 import "log"
 import "net/http"
+import "time"
 
 import "github.com/google/uuid"
 import "github.com/gorilla/mux"
@@ -22,7 +23,7 @@ func NewAPI(storePath string) *API {
 	}
 
 	api.router.HandleFunc("/template", returnError(jsonOutput(api.createTemplate))).Methods("POST").Headers("Content-Type", "application/json")
-	api.router.HandleFunc("/template/{id}", api.streamTemplate).Methods("GET").Headers("Accept", "text/event-stream")
+	api.router.HandleFunc("/template/{id}", returnError(api.streamTemplate)).Methods("GET").Headers("Accept", "text/event-stream")
 	api.router.HandleFunc("/template/{id}", returnError(jsonOutput(api.getTemplate))).Methods("GET")
 	api.router.HandleFunc("/template/{id}", returnError(jsonOutput(api.updateTemplate))).Methods("PATCH").Headers("Content-Type", "application/json")
 
@@ -33,7 +34,7 @@ func (api *API) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	api.router.ServeHTTP(w, r)
 }
 
-func (api *API) createTemplate(r *http.Request) (interface{}, string, int) {
+func (api *API) createTemplate(r *http.Request) (Object, string, int) {
 	log.Printf("createTemplate")
 
 	template := NewTemplate()
@@ -56,29 +57,50 @@ func (api *API) createTemplate(r *http.Request) (interface{}, string, int) {
 	return template, "", 0
 }
 
-func (api *API) streamTemplate(w http.ResponseWriter, r *http.Request) {
+func (api *API) streamTemplate(w http.ResponseWriter, r *http.Request) (string, int) {
 	log.Printf("streamTemplate %s", mux.Vars(r))
 
-	flusher, ok := w.(http.Flusher)
+	_, ok := w.(http.Flusher)
 	if !ok {
-		http.Error(w, "streaming unsupported", http.StatusBadRequest)
-		return
+		return "Streaming unsupported", http.StatusBadRequest
 	}
 
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-cache")
 	w.Header().Set("Connection", "keep-alive")
 
+	template := NewTemplate()
+	template.Id = mux.Vars(r)["id"]
+
+	err := api.store.Read(template)
+	if err != nil {
+		return fmt.Sprintf("Template %s not found", template.Id), http.StatusNotFound
+	}
+
+	writeEvent(w, template)
+
 	closeChan := w.(http.CloseNotifier).CloseNotify()
+	msgChan := api.bus.Subscribe(template)
+	ticker := time.NewTicker(5 * time.Second)
 
-	flusher.Flush()
-
-	<-closeChan
+	connected := true
+	for connected {
+		select {
+		case <-closeChan:
+			connected = false
+		case msg := <-msgChan:
+			writeEvent(w, msg)
+		case <-ticker.C:
+			writeEvent(w, NewHeartbeat())
+		}
+	}
 
 	log.Printf("streamTemplate %s end", mux.Vars(r))
+
+	return "", 0
 }
 
-func (api *API) getTemplate(r *http.Request) (interface{}, string, int) {
+func (api *API) getTemplate(r *http.Request) (Object, string, int) {
 	log.Printf("getTemplate %s", mux.Vars(r))
 
 	template := NewTemplate()
@@ -92,7 +114,7 @@ func (api *API) getTemplate(r *http.Request) (interface{}, string, int) {
 	return template, "", 0
 }
 
-func (api *API) updateTemplate(r *http.Request) (interface{}, string, int) {
+func (api *API) updateTemplate(r *http.Request) (Object, string, int) {
 	log.Printf("updateTemplate %s", mux.Vars(r))
 
 	patch := NewTemplate()
@@ -129,7 +151,7 @@ func (api *API) updateTemplate(r *http.Request) (interface{}, string, int) {
 
 }
 
-func readJson(r *http.Request, out interface{}) (string, int) {
+func readJson(r *http.Request, out Object) (string, int) {
 	dec := json.NewDecoder(r.Body)
 	dec.DisallowUnknownFields()
 
@@ -150,7 +172,7 @@ func returnError(wrapped func(http.ResponseWriter, *http.Request) (string, int))
 	}
 }
 
-func jsonOutput(wrapped func(*http.Request) (interface{}, string, int)) func(http.ResponseWriter, *http.Request) (string, int) {
+func jsonOutput(wrapped func(*http.Request) (Object, string, int)) func(http.ResponseWriter, *http.Request) (string, int) {
 	return func(w http.ResponseWriter, r *http.Request) (string, int) {
 		out, msg, code := wrapped(r)
 		if code != 0 {
@@ -166,3 +188,15 @@ func jsonOutput(wrapped func(*http.Request) (interface{}, string, int)) func(htt
 		return "", 0
 	}
 }
+
+func writeEvent(w http.ResponseWriter, in Object) (string, int) {
+	data, err := json.Marshal(in)
+	if err != nil {
+		return fmt.Sprintf("Failed to encode JSON: %s", err), http.StatusInternalServerError
+	}
+
+	fmt.Fprintf(w, "event: %s\ndata: %s\n\n", in.GetType(), data)
+	w.(http.Flusher).Flush()
+
+	return "", 0
+}

heartbeat.go

@@ -0,0 +1,16 @@
+package main
+
+type Heartbeat struct {
+}
+
+func NewHeartbeat() *Heartbeat {
+	return &Heartbeat{}
+}
+
+func (h *Heartbeat) GetType() string {
+	return "heartbeat"
+}
+
+func (h *Heartbeat) GetId() string {
+	return ""
+}