package main

import (
   "fmt"
   "net"
   "sync"
)

var mux sync.RWMutex
var onlineUser = make(map[string]net.Conn)
var messageChan = make(chan string)

func main() {
   listen, err := net.Listen("tcp", "127.0.0.1:8888")
   if err != nil {
      fmt.Printf("listen error %s\n", err)
   }

   defer listen.Close()

   go listenBroadMessage()

   for {
      conn, err := listen.Accept()
      if err != nil {
         fmt.Printf("conn error %s \n", err)
      }

      go handlerConn(conn)

   }
}

// listen broad message and send to all user
func listenBroadMessage() {
   for {
      msg := <-messageChan
      fmt.Println("收到消息：" + msg)
      for _, conn := range onlineUser {
         conn.Write([]byte(msg))
      }
   }
}

//broadcast message
func broadMessage(conn net.Conn, message string) {
   messageChan <- generateMessage(conn, message)
}


func generateMessage(conn net.Conn, msg string) string {
   return "[" + conn.RemoteAddr().String() + "]" + " " + msg + "\n"
}

// handler each user
func handlerConn(conn net.Conn) {
   addr := conn.RemoteAddr().String()
   broadMessage(conn, "进入了房间")

   mux.Lock()
   onlineUser[addr] = conn
   mux.Unlock()

   var isQuit = make(chan bool)
   go func() {
      buff := make([]byte, 4098)
      for {
         n, _ := conn.Read(buff)
         if n == 0 {
            isQuit <- true
            return
         }
         buffMsg := string(buff[:n-1])
         if buffMsg != "" {
            broadMessage(conn, buffMsg)
         }
      }

   }()

   for {
      select {
      case <-isQuit:
         delete(onlineUser, addr)
         broadMessage(conn, "离开了房间")
         return
      }
   }
}