chat.go

package main

import (
	"bufio"
	"fmt"
	"net"
)

type msgs chan string

type client struct {
	name   string
	msgbox msgs
}

var (
	messages = make(chan string)
	entering = make(chan client)
	leaving  = make(chan client)
)

func boradcast() {
	clients := make(map[client]bool)
	for {
		select {
		case msg := <-messages:
			for cli := range clients {
				cli.msgbox <- msg
			}

		case cli := <-leaving:
			delete(clients, cli)
			close(cli.msgbox)

		case cli := <-entering:
			clients[cli] = true
		}
	}
}

func writing(conn net.Conn, cli client) {
	for msg := range cli.msgbox {
		fmt.Fprintln(conn, msg)
	}
}

func handleConnect(conn net.Conn) {
	cli := client{
		name:   conn.RemoteAddr().String(),
		msgbox: make(msgs),
	}

	go writing(conn, cli)

	entering <- cli
	messages <- cli.name + " has joined the chat"

	scanner := bufio.NewScanner(conn)
	for scanner.Scan() {
		messages <- cli.name + ": " + scanner.Text()
	}

	leaving <- cli
	messages <- cli.name + " left the chat"
	conn.Close()
}

func main() {
	ln, _ := net.Listen("tcp", ":8080")

	go boradcast()

	for {
		conn, _ := ln.Accept()

		go handleConnect(conn)
	}
}