/*
 * Copyright 2010-2014 Ning, Inc.
 * Copyright 2014-2020 Groupon, Inc
 * Copyright 2020-2020 Equinix, Inc
 * Copyright 2014-2020 The Billing Project, LLC
 *
 * The Billing Project 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.killbill;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.UUID;

import org.killbill.commons.utils.Strings;
import org.killbill.commons.utils.annotation.VisibleForTesting;

public class CreatorName {

    private static final Object lock = new Object();

    // If set to true and QUEUE_CREATOR_NAME is not set, generate a UUID instead of using default hostname.
    static final String AUTO_GENERATED_QUEUE_CREATOR_NAME = "org.killbill.queue.creator.autoGeneratedName";

    // Allow to override the default naming based on Hostname
    static final String QUEUE_CREATOR_NAME = "org.killbill.queue.creator.name";

    private static String creatorName;

    public static String get() {
        if (creatorName == null) {
            synchronized (lock) {
                String tmpCreatorName = System.getProperty(QUEUE_CREATOR_NAME);
                if (Strings.emptyToNull(tmpCreatorName) == null) {
                    final boolean autoGenerateCreatorName = Boolean.parseBoolean(System.getProperty(AUTO_GENERATED_QUEUE_CREATOR_NAME, "false"));

                    if (autoGenerateCreatorName) {
                        tmpCreatorName = UUID.randomUUID().toString();
                    } else {
                        try {
                            final InetAddress addr = InetAddress.getLocalHost();
                            tmpCreatorName = addr.getHostName();
                        } catch (final UnknownHostException e) {
                            tmpCreatorName = "creatorName-unknown";
                        }
                    }
                }

                creatorName = tmpCreatorName.length() > 45 ? tmpCreatorName.substring(0, 45) : tmpCreatorName;
            }
        }

        return creatorName;
    }

    @VisibleForTesting
    static synchronized void reset() {
        creatorName = null;
    }
}
