package main

import (
  "fmt"
  "net"
  "io"
  "strconv"
  "time"
  "strings"
)

const (
  NORMAL_MESSAGE = iota
  LIST_MESSAGE
)

var clientSenders = make(map[string] chan string)

func send (addr string, conn *net.Conn){
  senderChan := clientSenders[addr]
  for s := range senderChan{
    (*conn).Write([]byte(s))
  }
}

func sendUsersInfo(addr string){
  senderChan := clientSenders[addr]
  if nil != senderChan{
    ls := strconv.Itoa(LIST_MESSAGE)
    cs := strconv.Itoa(NORMAL_MESSAGE) + "已登录客户端列表：\n"
    i := 1
    for k := range clientSenders{
      a := ""
      if k == addr {
        a = "（我）"
      }
      cs = cs + strconv.Itoa(i) + "）" + k + a + "\n"
      ls += k + "\n"
      i ++
    }
    cs += "发送消息，可使用 1<-这是给1号客户端的消息\n（请使用英文以获取最佳体验）\n"

    senderChan <- cs
    time.Sleep(time.Millisecond * 300)
    senderChan <- ls

    // 发送格式化的列表

    fmt.Println("已发送“登录用户信息”", addr)
  } else{
    fmt.Println("客户端接受通道不存在", addr)
  }
}

func serve (conn *net.Conn){
  connect := *conn

  addr := connect.RemoteAddr().String()

  fmt.Println(addr, "接入服务")

  senderChan := make(chan string, 3)
  clientSenders[addr] = senderChan

  // 启动发送
  go send(addr, conn)

  // 发送当前用户信息
  go sendUsersInfo(addr)

  buff := make([]byte, 10240)
  for {
    n, err := connect.Read(buff)
    if err != nil {
      if err == io.EOF {
        fmt.Println("客户端断开链接，", addr)
        delete(clientSenders, addr)
        return
      } else{
        fmt.Println(err)
      }
    }

    msg := string(buff[:n])

    // 刷新客户端列表
    if msg == "ls\n" {
      go sendUsersInfo(addr)
      continue
    }

    // 提取数据
    msgs := strings.Split(msg, "<-")
    if len(msg) < 2{
      senderChan <- string("数据格式不正确，请联系开发者")
      continue
    }

    aimAddr := msgs[0]
    aimSender := clientSenders[aimAddr]
    if aimSender == nil {
      senderChan <- string("客户端已下线，使用 ls 命令获取最新的客户端列表")
      continue
    }

    aimSender <- strconv.Itoa(NORMAL_MESSAGE) + "[from:" + addr + "]:" + strings.Join(msgs[1:], "<-")
  }
}

func main(){
  addr := ":8080"
  listener, err := net.Listen("tcp", addr)
  if err != nil{
    fmt.Println(err)
    return
  }

  // 启动消息调度器

  defer listener.Close()

  // 启动连接监听
  for {
    conn, err := listener.Accept()
    if err != nil {
      fmt.Println(err)
      continue
    }

    go serve(&conn)
  }
}

package main

import (
  "net"
  "fmt"
  "io"
  "os"
  "bufio"
  "sync"
  "time"
  "strings"
  "strconv"
)


var conn *net.Conn
var addrs []string

const (
  NORMAL_MESSAGE = iota
  LIST_MESSAGE
)

func read(conn2 *net.Conn){
  defer func() {
    fmt.Println("尝试重连")
    go connectServer()
  }()

  connect := *conn2
  buff := make([]byte, 20140)
  for {
    n, err := connect.Read(buff)
    if err != nil {
      if err == io.EOF{
        fmt.Println("结束")
        (*conn2).Close()
        conn = nil
        return
      } else{
        fmt.Println(err)
      }
    }

    msg := string(buff[:n])
    t, err := strconv.Atoi(string(msg[0]))
    msg = msg[1:]

    switch t {
    case NORMAL_MESSAGE:
      fmt.Print(msg)
      break
    case LIST_MESSAGE:
      // 解析客户端列表数据
      addrs = strings.Split(msg, "\n")
      fmt.Println("已接收客户端列表。\n")
      break
    default:
      fmt.Print(msg)
      break
    }
  }
}

func connectServer(){
  addr := "192.168.99.236:8080"
  fmt.Println("等待服务器开启中")
  conn2, err := net.Dial("tcp", addr)
  if err != nil {
    fmt.Print(err)
    fmt.Println("连接失败，10s后尝试")
    time.Sleep(10 * time.Second)
    go connectServer()
    return
  }

  fmt.Println("已连接")

  conn = &conn2
  go read(&conn2)
}

func send (){
  inputReader := bufio.NewReader(os.Stdout)
  for {
    input, err := inputReader.ReadString('\n')
    if err != nil {
      if err == io.EOF{
        return
      } else{
        fmt.Println(err)
      }
    }

    if input == "ls\n" {
      (*conn).Write([]byte(input))
      continue
    }

    msgs := strings.Split(input, "<-")
    if len(msgs) < 2 {
      fmt.Println("发送的姿势不正确，应该像这样 1<-给1号发送消息\n")
      continue
    }

    index, err := strconv.Atoi(msgs[0])
    if err != nil {
      fmt.Println("发送的姿势不正确，应该像这样 1<-给1号发送消息\n")
      continue
    }

    if len(addrs) <= index {
      fmt.Println("不存在第" + strconv.Itoa(index) + "个客户端\n")
      continue
    }

    addr := addrs[index-1]

    input = addr + "<-" + strings.Join(msgs[1:], "<-")

    if nil != conn {
      (*conn).Write([]byte(input))
    }
  }
}

func main (){
  var wg sync.WaitGroup
  wg.Add(2)
  go connectServer()
  go send()
  wg.Wait()

  defer func() {
    if nil != conn {
      (*conn).Close()
    }
  }()
}