package main

import (
	"fmt"
	"log"
	"net"
	"strings"
	"sync"
)

type Server struct { // 服務(wù)端內(nèi)容
	clients map[string]*Client
	lock    sync.Mutex
}

func (s *Server) delClient(client *Client) { // 客戶(hù)端關(guān)閉
	s.lock.Lock()
	defer s.lock.Unlock()
	delete(s.clients, client.name)
}

func (s *Server) addClient(client *Client) { // 客戶(hù)端關(guān)閉
	s.lock.Lock()
	defer s.lock.Unlock()
	s.clients[client.name] = client
}

func (s *Server) sendMsgToOtherClient(msg string, client *Client) { // 將消息發(fā)送給其他所有客戶(hù)端
	s.lock.Lock()
	defer s.lock.Unlock()
	// 將消息轉(zhuǎn)發(fā)給其他客戶(hù)端
	for _, c := range s.clients {
		if c != client {
			c.msgCh <- "msg-> " + client.name + ": " + msg + "\n"
		}
	}
}

type Client struct { // 定義客戶(hù)端
	conn   net.Conn
	name   string      // 當(dāng)前客戶(hù)端的名稱(chēng)
	msgCh  chan string // 發(fā)送消息的管道
	server *Server
}

func (c *Client) receive() { // 接收消息
	for msg := range c.msgCh {
		_, _ = c.conn.Write([]byte(msg))
	}
}

func (c *Client) close() {
	c.server.delClient(c)
	close(c.msgCh)
	_ = c.conn.Close()
}

func (c *Client) handle() { // 開(kāi)始處理連接
	_, _ = c.conn.Write([]byte(fmt.Sprintf("hello %s!\n", c.name))) // 發(fā)送歡迎信息
	c.server.sendMsgToOtherClient("join", c)                        // 通知大家, 有人加入了聊天室
	defer c.close()
	for {
		buf := make([]byte, 2048)
		n, err := c.conn.Read(buf) // 接收客戶(hù)端發(fā)送的消息
		if err != nil {
			log.Printf("receive client data error: %s", err.Error())
			return
		}

		msg := strings.TrimSpace(string(buf[:n]))
		if len(msg) == 0 {
			continue
		}
		if msg == "quit" {
			c.server.sendMsgToOtherClient("quit", c) // 通知大家, 有人退出了聊天室
			return
		}
		c.server.sendMsgToOtherClient(msg, c)
	}
}

func main() {
	// 監(jiān)聽(tīng)端口
	listener, err := net.Listen("tcp", ":8080")
	if err != nil {
		panic(err)
	}
	server := &Server{
		clients: make(map[string]*Client),
		lock:    sync.Mutex{},
	}

	nameIndex := 1
	for {
		conn, err := listener.Accept() // 建立連接
		if err != nil {
			log.Println(err)
			continue
		}

		client := &Client{
			conn:   conn,
			msgCh:  make(chan string, 100),
			name:   fmt.Sprintf("user%d", nameIndex),
			server: server,
		}
		nameIndex++
		server.addClient(client)
		go client.handle()
		go client.receive()
		log.Printf("new client: %s\n", conn.RemoteAddr())
	}
}