From b5aecea3225f29724c65be6b9109fb1c06fdb051 Mon Sep 17 00:00:00 2001
From: Antonio De Lucreziis <antonio.delucreziis@gmail.com>
Date: Thu, 3 Mar 2022 13:14:46 +0100
Subject: [PATCH] Added a mini server sent event handler library

---
 client/src/style.scss               |  4 +++
 server/httputil/serversentevents.go | 38 +++++++++++++++++++++++++++++
 server/httputil/sse_test.go         | 31 +++++++++++++++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 server/httputil/serversentevents.go
 create mode 100644 server/httputil/sse_test.go

diff --git a/client/src/style.scss b/client/src/style.scss
index 95c9e4c..06b2a0e 100644
--- a/client/src/style.scss
+++ b/client/src/style.scss
@@ -117,3 +117,7 @@ main {
         }
     }
 }
+
+img {
+    transform: rotate(180deg);
+}
diff --git a/server/httputil/serversentevents.go b/server/httputil/serversentevents.go
new file mode 100644
index 0000000..537a727
--- /dev/null
+++ b/server/httputil/serversentevents.go
@@ -0,0 +1,38 @@
+package httputil
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func HandleSSE(handler func(broadcast, single chan<- string)) http.Handler {
+	broadcast := make(chan string)
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		w.Header().Set("Cache-Control", "no-cache")
+		w.Header().Set("Connection", "keep-alive")
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+
+		client := make(chan string)
+		defer func() {
+			close(client)
+		}()
+
+		go handler(broadcast, client)
+
+		flusher, _ := w.(http.Flusher)
+		for {
+			select {
+			case message := <-broadcast:
+				fmt.Fprintf(w, "%s\n", message)
+				flusher.Flush()
+			case message := <-client:
+				fmt.Fprintf(w, "%s\n", message)
+				flusher.Flush()
+			case <-r.Context().Done():
+				return
+			}
+		}
+	})
+}
diff --git a/server/httputil/sse_test.go b/server/httputil/sse_test.go
new file mode 100644
index 0000000..d753b34
--- /dev/null
+++ b/server/httputil/sse_test.go
@@ -0,0 +1,31 @@
+package httputil_test
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"git.phc.dm.unipi.it/aziis98/posti-dm/server/httputil"
+)
+
+func TestSSE(t *testing.T) {
+	var broadcastChannel chan<- string
+
+	go func() {
+		for {
+			if broadcastChannel != nil {
+				broadcastChannel <- "Messaggio per tutti"
+			}
+			time.Sleep(1 * time.Second)
+		}
+	}()
+
+	http.Handle("/sse", httputil.HandleSSE(func(broadcast, single chan<- string) {
+		broadcastChannel = broadcast
+		time.Sleep(1 * time.Second)
+		single <- "Messaggio 1 per questo client"
+		single <- "Messaggio 2 per questo client"
+	}))
+
+	http.ListenAndServe(":8000", nil)
+}