protohackers/cmd/budgetchat/main.go

package main

import (
	"bufio"
	"fmt"
	"log"
	"net"
	"protohackers/pkg/conn"
)

type message struct {
	msg    []byte
	client *client
}

func msg(s string, c *client) message {
	return message{[]byte(s), c}
}

var (
	room     = make([]*client, 0)
	messages = make(chan message, 32)
)

func main() {
	go broadcast()
	err := conn.StartSimpleTCP(newUserHandler)
	if err != nil {
		log.Fatalln(err)
	}
}

func broadcast() {
	for {
		select {
		case m := <-messages:
			for _, cl := range room {
				if m.client == cl {
					continue
				}
				cl.sendMessage(m.msg)
			}
		}
	}
}

func userList() []byte {
	m := "* The room contains: "
	if len(room) > 0 {
		for _, c := range room {
			m += fmt.Sprintf("%s, ", c.name)
		}
		m = m[:len(m)-2]
	}
	return []byte(m + "\n")
}

func newUserHandler(c net.Conn) {
	cl, err := newClient(c)
	if err != nil {
		return
	}

	cl.sendMessage(userList())
	fmt.Printf("New client %s\n", cl.name)
	messages <- msg(fmt.Sprintf("* %s has entered the room\n", cl.name), cl)
	room = append(room, cl)

	input := bufio.NewScanner(cl.c)
	for input.Scan() {
		m := fmt.Sprintf("[%s] %s\n", cl.name, input.Text())
		messages <- msg(m, cl)
	}

	for i, p := range room {
		if p == cl {
			name := cl.name
			cl.c.Close()
			room = append(room[:i], room[i+1:]...)
			fmt.Printf("%s has left", cl.name)
			messages <- msg(fmt.Sprintf("* %s has left the room\n", name), cl)
			break
		}
	}
}