TradeServiceImpl.java

/*
 * Copyright 2002-2013 the original author or authors.
 *
 * Licensed 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 ch.rasc.s4ws.portfolio.service;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import ch.rasc.s4ws.portfolio.Portfolio;
import ch.rasc.s4ws.portfolio.PortfolioPosition;
import ch.rasc.s4ws.portfolio.service.Trade.TradeAction;

@Service
public class TradeServiceImpl implements TradeService {

	private static final Log logger = LogFactory.getLog(TradeServiceImpl.class);

	private final SimpMessageSendingOperations messagingTemplate;

	private final PortfolioService portfolioService;

	private final List<TradeResult> tradeResults = new CopyOnWriteArrayList<>();

	@Autowired
	public TradeServiceImpl(SimpMessageSendingOperations messagingTemplate,
			PortfolioService portfolioService) {
		this.messagingTemplate = messagingTemplate;
		this.portfolioService = portfolioService;
	}

	/**
	 * In real application a trade is probably executed in an external system, i.e.
	 * asynchronously.
	 */
	@Override
	public void executeTrade(Trade trade) {

		Portfolio portfolio = this.portfolioService.findPortfolio(trade.getUsername());
		String ticker = trade.getTicker();
		int sharesToTrade = trade.getShares();

		PortfolioPosition newPosition = trade.getAction() == TradeAction.Buy
				? portfolio.buy(ticker, sharesToTrade)
				: portfolio.sell(ticker, sharesToTrade);

		if (newPosition == null) {
			String payload = "Rejected trade " + trade;
			this.messagingTemplate.convertAndSendToUser(trade.getUsername(),
					"/queue/errors", payload);
			return;
		}

		this.tradeResults.add(new TradeResult(trade.getUsername(), newPosition));
	}

	@Scheduled(fixedDelay = 1500)
	public void sendTradeNotifications() {

		for (TradeResult result : this.tradeResults) {
			if (System.currentTimeMillis() >= result.timestamp + 1500) {
				logger.debug("Sending position update: " + result.position);
				this.messagingTemplate.convertAndSendToUser(result.user,
						"/queue/position-updates", result.position);
				this.tradeResults.remove(result);
			}
		}
	}

	private static class TradeResult {

		private final String user;

		private final PortfolioPosition position;

		private final long timestamp;

		public TradeResult(String user, PortfolioPosition position) {
			this.user = user;
			this.position = position;
			this.timestamp = System.currentTimeMillis();
		}
	}

}