From e2c2cbd0ef48e05aad3d4db5d6bb774ce24b861f Mon Sep 17 00:00:00 2001
From: Erik Brakkee <erik@brakkee.org>
Date: Fri, 19 Jul 2024 20:29:51 +0200
Subject: [PATCH] rendezvous mechanism with fixed id is now working.

---
 cmd/converge/server.go | 116 +++++++++++++++++++++++++++++++++++------
 1 file changed, 101 insertions(+), 15 deletions(-)

diff --git a/cmd/converge/server.go b/cmd/converge/server.go
index c8756ac..dda123a 100644
--- a/cmd/converge/server.go
+++ b/cmd/converge/server.go
@@ -6,6 +6,7 @@ import (
 	"github.com/gorilla/websocket"
 	"log"
 	"net/http"
+	"sync"
 )
 
 var upgrader = websocket.Upgrader{
@@ -34,33 +35,118 @@ func (endpoint *WebSocketService) handle(w http.ResponseWriter, r *http.Request)
 	handleWebSocket(w, r, endpoint.handler)
 }
 
-var client *iowrappers.WebSocketConn
-var agent *iowrappers.WebSocketConn
+type Agent struct {
+	agent          *iowrappers.WebSocketConn
+	publicId       string
+	client         *iowrappers.WebSocketConn
+	agentAvailable chan bool
+	clientClosed   chan bool
+}
+
+func NewAgent(publicId string,
+	agentConn *iowrappers.WebSocketConn,
+	clientConn *iowrappers.WebSocketConn) *Agent {
+	return &Agent{
+		agent:          agentConn,
+		publicId:       publicId,
+		client:         clientConn,
+		agentAvailable: make(chan bool),
+		clientClosed:   make(chan bool),
+	}
+}
+
+type Admin struct {
+	// map of public id to agent
+	mutex  sync.Mutex
+	agents map[string]*Agent
+}
+
+func NewAdmin() *Admin {
+	admin := Admin{
+		mutex:  sync.Mutex{},
+		agents: make(map[string]*Agent),
+	}
+	return &admin
+}
+
+func (admin *Admin) addAgent(publicId string, conn *iowrappers.WebSocketConn) (*Agent, error) {
+	admin.mutex.Lock()
+	defer admin.mutex.Unlock()
+
+	agent := admin.agents[publicId]
+	if agent != nil && agent.agent != nil && agent.agent != conn {
+		return nil, fmt.Errorf("A different agent with same publicId '%s' already registered", publicId)
+	}
+	if agent != nil {
+		agent.agent = conn
+		return agent, nil
+	}
+	agent = NewAgent(publicId, conn, nil)
+	admin.agents[publicId] = agent
+	return agent, nil
+}
+
+func (admin *Admin) addClient(publicId string, conn *iowrappers.WebSocketConn) (*Agent, error) {
+	admin.mutex.Lock()
+	defer admin.mutex.Unlock()
+
+	agent := admin.agents[publicId]
+	if agent != nil && agent.client != nil && agent.client != conn {
+		// we should setup on-demend connections ot agents later.
+		return nil, fmt.Errorf("A different client with same publicId '%s' already registered", publicId)
+	}
+	if agent != nil {
+		agent.client = conn
+		return agent, nil
+	}
+	agent = NewAgent(publicId, nil, conn)
+	admin.agents[publicId] = agent
+	return agent, nil
+}
+
+func (admin *Admin) Register(publicId string, conn *iowrappers.WebSocketConn) error {
+	defer conn.Close()
+	agent, err := admin.addAgent(publicId, conn)
+	if err != nil {
+		return err
+	}
+	agent.agentAvailable <- true
+	<-agent.clientClosed
+	return nil
+}
+
+func (admin *Admin) Connect(publicId string, conn *iowrappers.WebSocketConn) error {
+	defer conn.Close()
+	agent, err := admin.addClient(publicId, conn)
+	if err != nil {
+		return err
+	}
+	<-agent.agentAvailable
+	log.Println("Connecting websockets")
+	iowrappers.SynchronizeStreams(agent.client, agent.agent)
+	agent.clientClosed <- true
+	return nil
+}
 
 func main() {
-	// Connect to TCP server
-
-	clientClosed := make(chan bool)
-	serverAvailable := make(chan bool)
 
+	admin := NewAdmin()
 	registrationService := WebSocketService{
 		handler: func(w http.ResponseWriter, r *http.Request, conn *iowrappers.WebSocketConn) {
 			log.Println("Got registration connection")
-			agent = conn
-			serverAvailable <- true
-			<-clientClosed
+			err := admin.Register("abc123", conn)
+			if err != nil {
+				log.Printf("Error %v", err)
+			}
 		},
 	}
 	clientService := WebSocketService{
 		handler: func(w http.ResponseWriter, r *http.Request, conn *iowrappers.WebSocketConn) {
 			log.Println("Got client connection")
-			client = conn
-			if agent == nil {
-				log.Println("There is no agent yet,, closing")
-				return
+			err := admin.Connect("abc123", conn)
+			if err != nil {
+				log.Printf("Error %v", err)
 			}
-			iowrappers.SynchronizeStreams(client, agent)
-			clientClosed <- true
 		},
 	}