PlayerServiceImpl.java

// Copyright 2022 PingCAP, Inc.
//
// 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 com.pingcap.service.impl;

import com.pingcap.dao.PlayerBean;
import com.pingcap.dao.PlayerRepository;
import com.pingcap.service.PlayerService;
import jakarta.transaction.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * PlayerServiceImpl implements PlayerService interface
 * @Transactional it means every method in this class, will package by a pair of
 *     transaction.begin() and transaction.commit(). and it will be call
 *     transaction.rollback() when method throw an exception
 */
@Service
@Transactional
public class PlayerServiceImpl implements PlayerService {
    @Autowired
    private PlayerRepository playerRepository;

    @Override
    public Integer createPlayers(List<PlayerBean> players) {
        return playerRepository.saveAll(players).size();
    }

    @Override
    public void buyGoods(Long sellId, Long buyId, Integer amount, Integer price) throws RuntimeException {
        PlayerBean buyPlayer = playerRepository.getPlayerAndLock(buyId);
        PlayerBean sellPlayer = playerRepository.getPlayerAndLock(sellId);
        if (buyPlayer == null || sellPlayer == null) {
            throw new RuntimeException("sell or buy player not exist");
        }

        if (buyPlayer.getCoins() < price || sellPlayer.getGoods() < amount) {
            throw new RuntimeException("coins or goods not enough, rollback");
        }

        buyPlayer.setGoods(buyPlayer.getGoods() + amount);
        buyPlayer.setCoins(buyPlayer.getCoins() - price);
        playerRepository.save(buyPlayer);

        sellPlayer.setGoods(sellPlayer.getGoods() - amount);
        sellPlayer.setCoins(sellPlayer.getCoins() + price);
        playerRepository.save(sellPlayer);
    }

    @Override
    public PlayerBean getPlayerByID(Long id) {
        return playerRepository.findById(id).orElse(null);
    }

    @Override
    public List<PlayerBean> getPlayers(Integer limit) {
        return playerRepository.getPlayersByLimit(limit);
    }

    @Override
    public Page<PlayerBean> getPlayersByPage(Integer index, Integer size) {
        return playerRepository.getPlayersByPage(PageRequest.of(index, size));
    }

    @Override
    public Long countPlayers() {
        return playerRepository.count();
    }
}