/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * 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.alibaba.druid.spring;

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

public class SequenceService implements SequenceServiceMBean, ISequenceService {
    private Lock          lock      = new ReentrantLock();

    private ISequenceDao  dao;
    private String        name      = "druid-spring-test";

    private String        seed;

    private AtomicInteger increment = new AtomicInteger();

    public ISequenceDao getDao() {
        return dao;
    }

    public void setDao(ISequenceDao dao) {
        this.dao = dao;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSeed() {
        return this.seed;
    }

    @Transactional(propagation = Propagation.NOT_SUPPORTED)
    public long nextValue() {
        if (seed == null) {
            init();
        }

        int value = increment.getAndIncrement();

        String text = seed + "9" + Integer.toString(value);

        return Long.parseLong(text);
    }

    @Transactional(propagation = Propagation.NOT_SUPPORTED)
    public void init() {
        lock.lock();
        try {
            this.seed = nextSeed();
        } finally {
            lock.unlock();
        }
    }

    @Transactional(propagation = Propagation.NOT_SUPPORTED)
    public String nextSeed() {
        lock.lock();
        try {
            for (; ; ) {
                int value = dao.getValue(name);
                if (dao.compareAndSet(name, value + 1, value)) {
                    if (value == 0) {
                        return "";
                    } else {
                        return Integer.toString(value, 9);
                    }
                }
            }
        } finally {
            lock.unlock();
        }
    }

}