/*
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements.  See the NOTICE file distributed with
 *   this work for additional information regarding copyright ownership.
 *   The ASF licenses this file to You under the Apache License, Version 2.0
 *   (the "License"); you may not use this file except in compliance with
 *   the License.  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 *
 */

package org.apache.dubbo.samples.callback.provider;

import org.apache.dubbo.config.annotation.Argument;
import org.apache.dubbo.config.annotation.DubboService;
import org.apache.dubbo.config.annotation.Method;
import org.apache.dubbo.samples.callback.api.CallbackListener;
import org.apache.dubbo.samples.callback.api.CallbackService;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

@DubboService(token = "true", connections = 1, callbacks = 1000, methods = @Method(name = "addListener", arguments = @Argument(index = 1, callback = true)))
public class CallbackServiceImpl implements CallbackService {

    private final Map<String, CallbackListener> listeners = new ConcurrentHashMap<String, CallbackListener>();

    public CallbackServiceImpl() {
        Thread t = new Thread(() -> {
            while (true) {
                try {
                    for (Map.Entry<String, CallbackListener> entry : listeners.entrySet()) {
                        try {
                            entry.getValue().changed(getChanged(entry.getKey()));
                        } catch (Throwable t1) {
                            listeners.remove(entry.getKey());
                        }
                    }
                    Thread.sleep(5000); // timely trigger change event
                } catch (Throwable t1) {
                    t1.printStackTrace();
                }
            }
        });
        t.setDaemon(true);
        t.start();
    }

    @Override
    public void addListener(String key, CallbackListener listener) {
        listeners.put(key, listener);
        listener.changed(getChanged(key)); // send notification for change
    }

    private String getChanged(String key) {
        return "Changed: " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
    }

}
