1 files changed, 213 insertions, 0 deletions
diff --git a/internal/network/network.go b/internal/network/network.go
new file mode 100644
index 0000000..8283993
--- /dev/null
+++ b/internal/network/network.go
@@ -0,0 +1,213 @@
+package network
+
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+var logger *zap.Logger
+
+// PeerInfo represents a peer's ID and IP.
+type PeerInfo struct {
+	ID   string `json:"id"`
+	IP   string `json:"ip"`
+	Port int    `json:"port"`
+}
+
+// Message represents a structured message.
+type Message struct {
+	Type      string   `json:"type"`
+	Payload   []byte   `json:"payload"`
+	Source    PeerInfo `json:"source"`
+	Target    PeerInfo `json:"target"`
+	Timestamp int64    `json:"timestamp"`
+}
+
+type NetworkCallback func(msg Message)
+
+// TCPNetwork represents a full-duplex TCP peer.
+type TCPNetwork struct {
+	localPeer   PeerInfo
+	connections map[string]net.Conn
+	listener    net.Listener
+	callbacks   map[string]NetworkCallback
+	callbacksMu sync.RWMutex
+	isConnected bool
+	retryDelay  time.Duration
+	sync.Mutex
+}
+
+// initializes a TCP peer
+func NewTCPNetwork(localID, localIP string, localPort int) *TCPNetwork {
+	n := &TCPNetwork{
+		localPeer:   PeerInfo{ID: localID, IP: localIP, Port: localPort},
+		connections: make(map[string]net.Conn),
+		callbacks:   make(map[string]NetworkCallback),
+		isConnected: false,
+		retryDelay:  2 * time.Second,
+	}
+
+	go n.startServer()
+
+	logger, _ = zap.NewProduction()
+
+	return n
+}
+
+// Add a new peer connection to the local peer
+func (n *TCPNetwork) AddPeer(remoteID string, remoteIP string, remotePort int) {
+	go n.retryConnect(remoteID, remoteIP, remotePort)
+}
+
+// startServer starts a TCP server to accept connections.
+func (n *TCPNetwork) startServer() {
+	address := fmt.Sprintf("%s:%d", n.localPeer.IP, n.localPeer.Port)
+	listener, err := net.Listen("tcp", address)
+	if err != nil {
+		logger.Sugar().Errorf("failed to start server: %v", err)
+	}
+	n.listener = listener
+	logger.Sugar().Infof("server started on %s\n", address)
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			logger.Sugar().Errorf("failed to accept connection: %v\n", err)
+			continue
+		}
+
+		remoteAddr := conn.RemoteAddr().String()
+		n.Lock()
+		n.connections[remoteAddr] = conn
+		n.Unlock()
+		n.isConnected = true
+		n.retryDelay = 2 * time.Second
+
+		logger.Sugar().Infof("connected to remote peer %s\n", remoteAddr)
+		go n.listenForMessages(conn)
+	}
+}
+
+// retryConnect attempts to connect to a remote peer.
+func (n *TCPNetwork) retryConnect(remoteID, remoteIP string, remotePort int) {
+	for {
+		n.Lock()
+		_, exists := n.connections[remoteID]
+		n.Unlock()
+
+		if exists {
+			time.Sleep(5 * time.Second)
+			continue
+		}
+
+		address := fmt.Sprintf("%s:%d", remoteIP, remotePort)
+		conn, err := net.Dial("tcp", address)
+
+		if err != nil {
+			logger.Sugar().Errorf("failed to connect to %s: %v. Retrying in %v...", remoteID, err, n.retryDelay)
+			time.Sleep(n.retryDelay)
+			if n.retryDelay < 30*time.Second {
+				n.retryDelay *= 2
+			}
+			continue
+		}
+
+		n.Lock()
+		n.connections[remoteID] = conn
+		n.Unlock()
+		logger.Sugar().Infof("successfully connected to peer %s!", remoteID)
+
+		go n.listenForMessages(conn)
+	}
+}
+
+// Send sends a message to a specified remote peer.
+func (n *TCPNetwork) Send(remoteID, messageType string, payload []byte) error {
+	n.Lock()
+	conn, exists := n.connections[remoteID]
+	n.Unlock()
+
+	if !exists {
+		return fmt.Errorf("not connected to peer %s", remoteID)
+	}
+
+	msg := Message{
+		Type:      messageType,
+		Payload:   payload,
+		Source:    n.localPeer,
+		Target:    PeerInfo{ID: remoteID},
+		Timestamp: time.Now().Unix(),
+	}
+
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return fmt.Errorf("failed to marshal message: %v", err)
+	}
+
+	_, err = conn.Write(append(data, '\n'))
+	if err != nil {
+		logger.Sugar().Errorf("failed to send message to %s: %v. Reconnecting...", remoteID, err)
+		n.Lock()
+		delete(n.connections, remoteID)
+		n.Unlock()
+		go n.retryConnect(remoteID, "", 0)
+		return fmt.Errorf("failed to send message: %v", err)
+	}
+
+	return nil
+}
+
+// RegisterHandler registers a callback for a message type.
+func (n *TCPNetwork) RegisterHandler(messageType string, callback NetworkCallback) {
+	n.callbacksMu.Lock()
+	n.callbacks[messageType] = callback
+	n.callbacksMu.Unlock()
+}
+
+// listenForMessages listens for incoming messages.
+func (n *TCPNetwork) listenForMessages(conn net.Conn) {
+	reader := bufio.NewReader(conn)
+
+	for {
+		data, err := reader.ReadBytes('\n')
+		if err != nil {
+			logger.Debug("connection lost. Reconnecting...")
+			n.Lock()
+			for id, c := range n.connections {
+				if c == conn {
+					delete(n.connections, id)
+					go n.retryConnect(id, "", 0)
+					break
+				}
+			}
+			n.Unlock()
+			return
+		}
+
+		var message Message
+		if err := json.Unmarshal(data, &message); err != nil {
+			logger.Sugar().Errorf("failed to unmarshal message: %v\n", err)
+			continue
+		}
+
+		n.callbacksMu.RLock()
+		callback, exists := n.callbacks[message.Type]
+		n.callbacksMu.RUnlock()
+
+		if exists {
+			go callback(message)
+		}
+	}
+}
+
+func (n *TCPNetwork) IsConnected() bool {
+	n.Lock()
+	defer n.Unlock()
+	return n.isConnected
+}