package websocket;

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.stream.Collectors;

@ServerEndpoint("/websocket")
public class ChatServer {
 //concurrent包的线程安全Set,用来存放每个客户端对应的ChatServer对象。
 // 若要实现服务端与单一客户端通信的话,可以使用Map来存放,其中Key可以为用户标识
 private static CopyOnWriteArraySet<ChatServer> webSocketSet = new CopyOnWriteArraySet<>();

 // 昵称
 private String nickname;

 //与某个客户端的连接会话,需要通过它来给客户端发送数据
 private Session session;

 /**
 * 连接建立成功调用的方法
 *
 * @param session 可选的参数。session为与某个客户端的连接会话,需要通过它来给客户端发送数据
 */
 @OnOpen
 public void onOpen(Session session) {
 this.session = session;
 webSocketSet.add(this); //加入set中
 }

 /**
 * 连接关闭调用的方法
 */
 @OnClose
 public void onClose() {
 webSocketSet.remove(this); //从set中删除
 List<String> users = webSocketSet.stream().map(u -> u.nickname).collect(Collectors.toList());
 ChatMsg chatMsg = new ChatMsg();
 chatMsg.type = ChatType.Msg.name();
 chatMsg.nickname = "系统消息";
 chatMsg.msg = "【" + nickname + "】下线";
 chatMsg.users = users;
 sendMsg2All(chatMsg, true);
 }

 /**
 * 收到客户端消息后调用的方法
 *
 * @param message 客户端发送过来的消息
 * @param session 可选的参数
 */
 @OnMessage
 public void onMessage(String message, Session session) {
 System.out.println("来自客户端的消息:" + message);
 ChatMsg chatMsg = ChatMsg.fromClientMsg(message);

 if (chatMsg.type.equals(ChatType.Connection.name())) {
 nickname = chatMsg.nickname;
 List<String> users = webSocketSet.stream().map(u -> u.nickname).collect(Collectors.toList());
 chatMsg = ChatMsg.newUser(nickname, users);
 sendMsg2All(chatMsg, false);
 return;
 }
 sendMsg2All(chatMsg, true);
 }

 /*
 * 发生错误时调用
 */
 @OnError
 public void onError(Session session, Throwable error) {
 System.out.println("发生错误");
 error.printStackTrace();
 }

 private void sendMsg2All(ChatMsg chatMsg, boolean withoutMyself) {
 String msg = chatMsg.toJson();
 for (ChatServer item : webSocketSet) {
 if (withoutMyself && this == item) {
 continue;
 }
 try {
 item.sendMessage(msg);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 }

 private void sendMessage(String message) throws IOException {
 this.session.getBasicRemote().sendText(message);
 }

}