From 62bdbc97a0d56ec66b58551587381cac72c9e1ff Mon Sep 17 00:00:00 2001
From: Dan <dan@localhost.localdomain>
Date: Sat, 7 Nov 2020 14:18:02 +0200
Subject: [PATCH] Add project

---
 client.go  | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 go.mod     |   5 +++
 go.sum     |   2 ++
 hub.go     |  40 +++++++++++++++++++++
 index.html |  98 ++++++++++++++++++++++++++++++++++++++++++++++++++
 main.go    |  36 +++++++++++++++++++
 6 files changed, 284 insertions(+)
 create mode 100644 client.go
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 hub.go
 create mode 100644 index.html
 create mode 100644 main.go

diff --git a/client.go b/client.go
new file mode 100644
index 0000000..996ae75
--- /dev/null
+++ b/client.go
@@ -0,0 +1,103 @@
+package main
+
+import (
+	"bytes"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	writeWait      = 10 * time.Second
+	pongWait       = 60 * time.Second
+	pingPeriod     = (pongWait * 9) / 10
+	maxMessageSize = 512
+)
+
+var (
+	newLine = []byte{'\n'}
+	space   = []byte{' '}
+)
+
+var upgrader = websocket.Upgrader{}
+
+type Client struct {
+	hub  *Hub
+	conn *websocket.Conn
+	send chan []byte
+}
+
+func (c *Client) readPump() {
+	defer func() {
+		c.hub.unregister <- c
+		c.conn.Close()
+	}()
+	c.conn.SetReadLimit(maxMessageSize)
+	c.conn.SetReadDeadline(time.Now().Add(pongWait))
+	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		_, message, err := c.conn.ReadMessage()
+		if err != nil {
+			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
+				log.Printf("error: %v", err)
+			}
+			break
+		}
+		message = bytes.TrimSpace(bytes.Replace(message, newLine, space, -1))
+		c.hub.broadcast <- message
+	}
+}
+
+func (c *Client) writePump() {
+	ticker := time.NewTicker(pingPeriod)
+	defer func() {
+		ticker.Stop()
+		c.conn.Close()
+	}()
+	for {
+		select {
+		case message, ok := <-c.send:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if !ok {
+				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+
+			w, err := c.conn.NextWriter(websocket.TextMessage)
+			if err != nil {
+				return
+			}
+			w.Write(message)
+
+			n := len(c.send)
+			for i := 0; i < n; i++ {
+				w.Write(newLine)
+				w.Write(<-c.send)
+			}
+
+			if err := w.Close(); err != nil {
+				return
+			}
+		case <-ticker.C:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
+				return
+			}
+		}
+	}
+}
+
+func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
+	conn, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
+	client.hub.register <- client
+
+	go client.writePump()
+	go client.readPump()
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..8d78f96
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module go-websocket-example
+
+go 1.15
+
+require github.com/gorilla/websocket v1.4.2 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..85efffd
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
diff --git a/hub.go b/hub.go
new file mode 100644
index 0000000..9a8ffcb
--- /dev/null
+++ b/hub.go
@@ -0,0 +1,40 @@
+package main
+
+type Hub struct {
+	clients    map[*Client]bool
+	broadcast  chan []byte
+	register   chan *Client
+	unregister chan *Client
+}
+
+func newHub() *Hub {
+	return &Hub{
+		broadcast:  make(chan []byte),
+		register:   make(chan *Client),
+		unregister: make(chan *Client),
+		clients:    make(map[*Client]bool),
+	}
+}
+
+func (h *Hub) run() {
+	for {
+		select {
+		case client := <-h.register:
+			h.clients[client] = true
+		case client := <-h.unregister:
+			if _, ok := h.clients[client]; ok {
+				delete(h.clients, client)
+				close(client.send)
+			}
+		case message := <-h.broadcast:
+			for client := range h.clients {
+				select {
+				case client.send <- message:
+				default:
+					close(client.send)
+					delete(h.clients, client)
+				}
+			}
+		}
+	}
+}
diff --git a/index.html b/index.html
new file mode 100644
index 0000000..67199f9
--- /dev/null
+++ b/index.html
@@ -0,0 +1,98 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<title>Chat Example</title>
+<script type="text/javascript">
+window.onload = function () {
+    var conn;
+    var msg = document.getElementById("msg");
+    var log = document.getElementById("log");
+
+    function appendLog(item) {
+        var doScroll = log.scrollTop > log.scrollHeight - log.clientHeight - 1;
+        log.appendChild(item);
+        if (doScroll) {
+            log.scrollTop = log.scrollHeight - log.clientHeight;
+        }
+    }
+
+    document.getElementById("form").onsubmit = function () {
+        if (!conn) {
+            return false;
+        }
+        if (!msg.value) {
+            return false;
+        }
+        conn.send(msg.value);
+        msg.value = "";
+        return false;
+    };
+
+    if (window["WebSocket"]) {
+        conn = new WebSocket("ws://" + document.location.host + "/ws");
+        conn.onclose = function (evt) {
+            var item = document.createElement("div");
+            item.innerHTML = "<b>Connection closed.</b>";
+            appendLog(item);
+        };
+        conn.onmessage = function (evt) {
+            var messages = evt.data.split('\n');
+            for (var i = 0; i < messages.length; i++) {
+                var item = document.createElement("div");
+                item.innerText = messages[i];
+                appendLog(item);
+            }
+        };
+    } else {
+        var item = document.createElement("div");
+        item.innerHTML = "<b>Your browser does not support WebSockets.</b>";
+        appendLog(item);
+    }
+};
+</script>
+<style type="text/css">
+html {
+    overflow: hidden;
+}
+
+body {
+    overflow: hidden;
+    padding: 0;
+    margin: 0;
+    width: 100%;
+    height: 100%;
+    background: gray;
+}
+
+#log {
+    background: white;
+    margin: 0;
+    padding: 0.5em 0.5em 0.5em 0.5em;
+    position: absolute;
+    top: 0.5em;
+    left: 0.5em;
+    right: 0.5em;
+    bottom: 3em;
+    overflow: auto;
+}
+
+#form {
+    padding: 0 0.5em 0 0.5em;
+    margin: 0;
+    position: absolute;
+    bottom: 1em;
+    left: 0px;
+    width: 100%;
+    overflow: hidden;
+}
+
+</style>
+</head>
+<body>
+<div id="log"></div>
+<form id="form">
+    <input type="submit" value="Send" />
+    <input type="text" id="msg" size="64" autofocus />
+</form>
+</body>
+</html>
\ No newline at end of file
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..d289d09
--- /dev/null
+++ b/main.go
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net/http"
+)
+
+var addr = flag.String("addr", ":8080", "http service address")
+
+func serveIndex(w http.ResponseWriter, r *http.Request) {
+	log.Println(r.URL)
+	if r.URL.Path != "/" {
+		http.Error(w, "Not found", http.StatusNotFound)
+		return
+	}
+	if r.Method != "GET" {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	http.ServeFile(w, r, "index.html")
+}
+
+func main() {
+	flag.Parse()
+	hub := newHub()
+	go hub.run()
+	http.HandleFunc("/", serveIndex)
+	http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
+		serveWs(hub, w, r)
+	})
+	err := http.ListenAndServe(*addr, nil)
+	if err != nil {
+		log.Fatal("Liatend and serve: ", err)
+	}
+}