/*
 * Copyright 1999-2018 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.pool.ha.selector;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.logging.Log;
import com.alibaba.druid.support.logging.LogFactory;
import com.alibaba.druid.util.JdbcUtils;

import javax.sql.DataSource;

import java.sql.Connection;

/**
 * A Thread trying to test if DataSource in blacklist has been recovered.
 *
 * @author DigitalSonic
 */
public class RandomDataSourceRecoverThread implements Runnable {
    public static final int DEFAULT_RECOVER_INTERVAL_SECONDS = 120;
    private static final Log LOG = LogFactory.getLog(RandomDataSourceRecoverThread.class);

    private RandomDataSourceSelector selector;
    private int recoverIntervalSeconds = DEFAULT_RECOVER_INTERVAL_SECONDS;
    private int validationSleepSeconds;

    public RandomDataSourceRecoverThread(RandomDataSourceSelector selector) {
        this.selector = selector;
    }

    @Override
    public void run() {
        while (true) {
            if (selector != null && selector.getBlacklist() != null
                    && !selector.getBlacklist().isEmpty()) {
                LOG.info(selector.getBlacklist().size() + " DataSource in blacklist.");
                for (DataSource dataSource : selector.getBlacklist()) {
                    if (!(dataSource instanceof DruidDataSource)) {
                        continue;
                    }
                    tryOneDataSource((DruidDataSource) dataSource);
                }
            } else if (selector == null) {
                break;
            }
            sleep();
        }
    }

    private void tryOneDataSource(DruidDataSource dataSource) {
        if (dataSource == null) {
            return;
        }
        Connection connection = null;
        try {
            connection = dataSource.getConnection();
            sleepBeforeValidation();
            dataSource.validateConnection(connection);
            LOG.info(dataSource.getName() + " is available now.");
            selector.removeBlacklist(dataSource);
        } catch (Exception e) {
            LOG.warn("DataSource[" + dataSource.getName() + "] is still unavailable. Exception: "
                    + e.getMessage());
        } finally {
            JdbcUtils.close(connection);
        }
    }

    private void sleepBeforeValidation() {
        if (validationSleepSeconds > 0) {
            try {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Sleep " + validationSleepSeconds + " second(s) before validation.");
                }
                Thread.sleep(validationSleepSeconds * 1000L);
            } catch (InterruptedException e) {
                // ignore
            }
        }
    }

    private void sleep() {
        try {
            Thread.sleep(recoverIntervalSeconds * 1000L);
        } catch (InterruptedException e) {
            // ignore
        }
    }

    public int getRecoverIntervalSeconds() {
        return recoverIntervalSeconds;
    }

    public void setRecoverIntervalSeconds(int recoverIntervalSeconds) {
        this.recoverIntervalSeconds = recoverIntervalSeconds;
    }

    public int getValidationSleepSeconds() {
        return validationSleepSeconds;
    }

    public void setValidationSleepSeconds(int validationSleepSeconds) {
        this.validationSleepSeconds = validationSleepSeconds;
    }

    public RandomDataSourceSelector getSelector() {
        return selector;
    }

    public void setSelector(RandomDataSourceSelector selector) {
        this.selector = selector;
    }
}
