From 3136bd00ef137c158b377aa3371638dc5e1a6bc1 Mon Sep 17 00:00:00 2001
From: Iyad ELwy <iyadelwy1@gmail.com>
Date: Mon, 20 May 2024 00:30:11 +0200
Subject: [PATCH] command line chat example

---
 examples/cmd-chat/client/main.go | 81 ++++++++++++++++++++++++++++
 examples/cmd-chat/server/main.go | 93 ++++++++++++++++++++++++++++++++
 2 files changed, 174 insertions(+)
 create mode 100644 examples/cmd-chat/client/main.go
 create mode 100644 examples/cmd-chat/server/main.go

diff --git a/examples/cmd-chat/client/main.go b/examples/cmd-chat/client/main.go
new file mode 100644
index 0000000..db4610b
--- /dev/null
+++ b/examples/cmd-chat/client/main.go
@@ -0,0 +1,81 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"os"
+	"os/signal"
+
+	"github.com/gorilla/websocket"
+)
+
+func main() {
+	connUserId := rand.Intn(100)
+	header := http.Header{}
+	header.Add("user-id", fmt.Sprint(connUserId))
+
+	dialer := websocket.Dialer{}
+	conn, _, err := dialer.Dial("ws://localhost:4000", header)
+	if err != nil {
+		err := conn.WriteMessage(websocket.CloseMessage,
+			websocket.FormatCloseMessage(websocket.CloseInternalServerErr, err.Error()))
+		if err != nil {
+			conn.Close()
+			os.Exit(1)
+		}
+		os.Exit(0)
+	}
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	go func() {
+		for range c {
+			err := conn.WriteMessage(websocket.CloseMessage,
+				websocket.FormatCloseMessage(websocket.CloseNormalClosure,
+					fmt.Sprintf("User %d closing connection", connUserId)))
+			if err != nil {
+				conn.Close()
+				os.Exit(1)
+			}
+			os.Exit(0)
+		}
+	}()
+
+	reader := bufio.NewReader(os.Stdin)
+	go func() {
+		for {
+			fmt.Print(fmt.Sprintf("%d: ", connUserId))
+			text, _ := reader.ReadString('\n')
+
+			err = conn.WriteMessage(websocket.TextMessage, []byte(text))
+			if err != nil {
+				err := conn.WriteMessage(websocket.CloseMessage,
+					websocket.FormatCloseMessage(websocket.CloseInternalServerErr, err.Error()))
+				if err != nil {
+					conn.Close()
+					os.Exit(1)
+				}
+				os.Exit(0)
+			}
+		}
+	}()
+
+	for {
+		_, p, err := conn.ReadMessage()
+		if err != nil {
+			err := conn.WriteMessage(websocket.CloseInternalServerErr,
+				websocket.FormatCloseMessage(websocket.CloseNormalClosure, err.Error()))
+			if err != nil {
+				conn.Close()
+				os.Exit(1)
+			}
+			os.Exit(0)
+		}
+		fmt.Printf("\n%s", p)
+		fmt.Print(fmt.Sprintf("%d: ", connUserId))
+
+	}
+
+}
diff --git a/examples/cmd-chat/server/main.go b/examples/cmd-chat/server/main.go
new file mode 100644
index 0000000..0b991ac
--- /dev/null
+++ b/examples/cmd-chat/server/main.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+	CheckOrigin: func(r *http.Request) bool {
+		return true
+	},
+}
+
+var connections = make(map[string]*websocket.Conn)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	conn, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		http.Error(w, "Bad Request", http.StatusBadRequest)
+		fmt.Println("Upgrade error:", err)
+		return
+	}
+
+	connUserId := r.Header.Get("user-id")
+	connections[connUserId] = conn
+
+	alterCloseHandlerToRemoveConnections(conn, connUserId)
+
+	go func() {
+		defer conn.Close()
+		for {
+			_, p, err := conn.ReadMessage()
+			if err != nil {
+				switch {
+				case websocket.IsCloseError(err, websocket.CloseNormalClosure):
+					err = broadcastMessage(fmt.Sprintf("User %s left the chat\n", connUserId), connUserId)
+					if err != nil {
+						conn.Close()
+					}
+				default:
+					fmt.Println(err)
+					err = broadcastMessage(fmt.Sprintf("User %s disconnected unexpectedly\n", connUserId), connUserId)
+					if err != nil {
+						conn.Close()
+					}
+					conn.CloseHandler()(websocket.CloseNormalClosure, "")
+				}
+				return
+			}
+			err = broadcastMessage(fmt.Sprintf("%s: %s", connUserId, p), connUserId)
+			if err != nil {
+				conn.Close()
+			}
+		}
+	}()
+}
+
+func main() {
+	http.HandleFunc("/", handler)
+	fmt.Println("Server started on :4000")
+	err := http.ListenAndServe(":4000", nil)
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+func broadcastMessage(message, connUserId string) error {
+	for cuid, con := range connections {
+		if cuid != connUserId {
+			err := con.WriteMessage(websocket.TextMessage, []byte(message))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func alterCloseHandlerToRemoveConnections(conn *websocket.Conn, connUserId string) {
+	conn.SetCloseHandler(func(code int, text string) error {
+		delete(connections, connUserId)
+		message := websocket.FormatCloseMessage(code, "")
+		if err := conn.WriteControl(websocket.CloseMessage, message, time.Now().Add(time.Second)); err != nil {
+			return err
+		}
+		return nil
+	})
+}