examples: Add chat example that also doesn't work properly yet

examples/chat/server/main.go

@@ -0,0 +1,164 @@
+package main
+
+import "os"
+import "fmt"
+import "log"
+import "errors"
+import "crypto/tls"
+import "git.tebibyte.media/sashakoshka/hopp"
+import "git.tebibyte.media/sashakoshka/go-util/sync"
+import "git.tebibyte.media/sashakoshka/go-util/container"
+import "git.tebibyte.media/sashakoshka/hopp/examples/chat"
+
+var clients usync.RWMonitor[ucontainer.Set[*client]]
+
+func main() {
+	name := os.Args[0]
+	if len(os.Args) != 4 {
+		fmt.Fprintf(os.Stderr, "Usage: %s HOST:PORT CERT KEY\n", name)
+		os.Exit(2)
+	}
+	address  := os.Args[1]
+	certPath := os.Args[2]
+	keyPath  := os.Args[3]
+	err := host(address, certPath, keyPath)
+	handleErr(1, err)
+}
+
+func host(address string, certPath, keyPath string) error {
+	keyPair, err := tls.LoadX509KeyPair(certPath, keyPath)
+	if err != nil { return err }
+	listener, err := hopp.ListenQUIC("quic", address, &tls.Config {
+		InsecureSkipVerify: true,
+		Certificates: []tls.Certificate { keyPair },
+	})
+	clients.Set(ucontainer.NewSet[*client]())
+	if err != nil { return err }
+	log.Printf("(i) hosting on %s", address)
+	for {
+		conn, err := listener.Accept()
+		if err != nil { return err }
+		client := &client {
+			conn: conn,
+			rooms: usync.NewRWMonitor(make(map[string] hopp.Trans)),
+		}
+		go client.run()
+	}
+}
+
+type client struct {
+	conn     hopp.Conn
+	nickname hopp.Option[string]
+	rooms    usync.RWMonitor[map[string] hopp.Trans]
+}
+
+func (this *client) run() {
+	log.Printf("-=E %v connected", this.conn.RemoteAddr())
+	defer log.Printf("X=- %v disconnected", this.conn.RemoteAddr())
+	defer this.conn.Close()
+
+	for {
+		log.Println("accepting transaction")
+		trans, err := this.conn.AcceptTrans()
+		log.Println("accepted transaction")
+		if err != nil {
+			log.Printf("XXX %v failed: %v", this.conn.RemoteAddr(), err)
+		}
+		go this.runTrans(trans)
+	}
+}
+
+func (this *client) runTrans(trans hopp.Trans) {
+	defer trans.Close()
+	message, err := chat.Receive(trans)
+	if err != nil {
+		log.Printf(
+			"XXX %v transaction failed: %v",
+			this.conn.RemoteAddr(), err)
+	}
+	switch message := message.(type) {
+	case *chat.MessageJoin:
+		err = this.transTalk(trans, message)
+	}
+	if err != nil {
+		var actual *chat.MessageError
+		if !errors.As(err, &actual) {
+			chat.Send(trans, &chat.MessageError {
+				Description: hopp.O(fmt.Sprint(err)),
+			})
+		}
+		log.Printf("XXX %v transaction failed: %v", this.conn.RemoteAddr(), err)
+	}
+}
+
+func (this *client) transTalk(trans hopp.Trans, initial *chat.MessageJoin) error {
+	room := initial.Room
+	err := this.joinRoom(trans, room)
+	if err != nil { return err }
+	defer this.leaveRoom(trans, room)
+	for {
+		message, err := chat.Receive(trans)
+		if err != nil { return err }
+		switch message := message.(type) {
+		case *chat.MessageChat:
+			err := this.handleMessageChat(trans, room, message)
+			if err != nil { return err }
+		case *chat.MessageError:
+			return message
+		}
+	}
+}
+
+func (this *client) handleMessageChat(trans hopp.Trans, room string, message *chat.MessageChat) error {
+	log.Println("(). %s #%s: %s", this.nickname.Default("Anonymous"), room, message.Content)
+	clients, done := clients.RBorrow()
+	defer done()
+	for client := range clients {
+		err := client.relayMessage(room, message)
+		if err != nil {
+			log.Printf("!!! %v", err)
+		}
+	}
+	return nil
+}
+
+func (this *client) relayMessage(room string, message *chat.MessageChat) error {
+	rooms, done := this.rooms.RBorrow()
+	defer done()
+	if trans, ok := rooms[room]; ok {
+		err := chat.Send(trans, message)
+		if err != nil {
+			return fmt.Errorf("could not relay message: %w", err)
+		}
+	}
+	return nil
+}
+
+func (this *client) joinRoom(trans hopp.Trans, room string) error {
+	rooms, done := this.rooms.Borrow()
+	defer done()
+	if _, exists := rooms[room]; exists {
+		return fmt.Errorf("already joined %s", room)
+	}
+	rooms[room] = trans
+	log.Printf("--> user %s joined #%s", this.nickname.Default("Anonymous"), room)
+	return nil
+}
+
+func (this *client) leaveRoom(trans hopp.Trans, room string) error {
+	rooms, done := this.rooms.Borrow()
+	defer done()
+	if _, exists := rooms[room]; !exists {
+		return fmt.Errorf("not in %s", room)
+	}
+	delete(rooms, room)
+	log.Printf("<-- user %s left #%s", this.nickname.Default("Anonymous"), room)
+	return nil
+}
+
+func handleErr(code int, err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
+		os.Exit(code)
+	}
+}