Add solution for Challenge 8 by nosrio

challenge-8/submissions/nosrio/solution-template.go

@@ -0,0 +1,163 @@
+// Package challenge8 contains the solution for Challenge 8: Chat Server with Channels.
+package challenge8
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	// Add any other necessary imports
+)
+
+// Client represents a connected chat client
+type Client struct {
+	// TODO: Implement this struct
+	// Hint: username, message channel, mutex, disconnected flag
+	Username  string
+	Connected bool
+	ready     chan bool
+	Messages  chan string
+	server    *ChatServer
+	msgMutx   sync.RWMutex
+}
+
+// Send sends a message to the client
+func (c *Client) Send(message string) {
+	// TODO: Implement this method
+	// Hint: thread-safe, non-blocking send
+	if !c.Connected {
+		return
+	}
+	c.msgMutx.Lock()
+	defer c.msgMutx.Unlock()
+	c.Messages <- message
+}
+
+// Receive returns the next message for the client (blocking)
+func (c *Client) Receive() string {
+	// TODO: Implement this method
+	// Hint: read from channel, handle closed channel
+	c.msgMutx.RLock()
+	defer c.msgMutx.RUnlock()
+	msg, ok := <-c.Messages
+	if !ok {
+		return ""
+	}
+	return msg
+}
+
+// ChatServer manages client connections and message routing
+type ChatServer struct {
+	// TODO: Implement this struct
+	// Hint: clients map, mutex
+	clients   map[string]*Client
+	broadcast chan string
+	join      chan *Client
+	leave     chan *Client
+	mu        sync.RWMutex
+}
+
+// NewChatServer creates a new chat server instance
+func NewChatServer() *ChatServer {
+	// TODO: Implement this function
+	cs := &ChatServer{
+		clients:   make(map[string]*Client),
+		broadcast: make(chan string),
+		join:      make(chan *Client),
+		leave:     make(chan *Client),
+		mu:        sync.RWMutex{},
+	}
+	go cs.run()
+
+	return cs
+}
+
+func (s *ChatServer) run() {
+	for {
+		select {
+		case client := <-s.join:
+			s.mu.Lock()
+			s.clients[client.Username] = client
+			client.ready <- true
+			s.mu.Unlock()
+		case client := <-s.leave:
+			s.mu.Lock()
+			delete(s.clients, client.Username)
+			client.ready <- true
+			s.mu.Unlock()
+		case message := <-s.broadcast:
+			s.mu.Lock()
+			for _, c := range s.clients {
+				c.Messages <- message
+			}
+			s.mu.Unlock()
+		}
+	}
+}
+
+// Connect adds a new client to the chat server
+func (s *ChatServer) Connect(username string) (*Client, error) {
+	// TODO: Implement this method
+	// Hint: check username, create client, add to map
+	if _, ok := s.clients[username]; ok {
+		return nil, ErrUsernameAlreadyTaken
+	}
+
+	c := &Client{
+		Username:  username,
+		Connected: true,
+		ready:     make(chan bool, 1),
+		Messages:  make(chan string),
+		server:    s,
+		msgMutx:   sync.RWMutex{},
+	}
+
+	s.join <- c
+	<-c.ready
+	return c, nil
+}
+
+// Disconnect removes a client from the chat server
+func (s *ChatServer) Disconnect(client *Client) {
+	// TODO: Implement this method
+	// Hint: remove from map, close channels
+	if _, exists := s.clients[client.Username]; !exists {
+		return
+	}
+	client.Connected = false
+	s.leave <- client
+	<-client.ready
+	close(client.Messages)
+}
+
+// Broadcast sends a message to all connected clients
+func (s *ChatServer) Broadcast(sender *Client, message string) {
+	// TODO: Implement this method
+	// Hint: format message, send to all clients
+	msg := fmt.Sprintf("[%s] %s", sender.Username, message)
+
+	s.broadcast <- msg
+}
+
+// PrivateMessage sends a message to a specific client
+func (s *ChatServer) PrivateMessage(sender *Client, recipient string, message string) error {
+	// TODO: Implement this method
+	// Hint: find recipient, check errors, send message
+	if !sender.Connected {
+		return ErrClientDisconnected
+	}
+	r, exists := s.clients[recipient]
+	if !exists {
+		return ErrRecipientNotFound
+	}
+	r.Messages <- fmt.Sprintf("[%s] %s", sender.Username, message)
+
+	return nil
+}
+
+// Common errors that can be returned by the Chat Server
+var (
+	ErrUsernameAlreadyTaken = errors.New("username already taken")
+	ErrRecipientNotFound    = errors.New("recipient not found")
+	ErrClientDisconnected   = errors.New("client disconnected")
+	// Add more error types as needed
+)