/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.zookeeper.recipes.lock;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Represents an ephemeral znode name which has an ordered sequence number
 * and can be sorted in order
 *
 */
class ZNodeName implements Comparable<ZNodeName> {
    private final String name;
    private String prefix;
    private int sequence = -1;
    private static final Logger LOG = LoggerFactory.getLogger(ZNodeName.class);
    
    public ZNodeName(String name) {
        if (name == null) {
            throw new NullPointerException("id cannot be null");
        }
        this.name = name;
        this.prefix = name;
        int idx = name.lastIndexOf('-');
        if (idx >= 0) {
            this.prefix = name.substring(0, idx);
            try {
                this.sequence = Integer.parseInt(name.substring(idx + 1));
                // If an exception occurred we misdetected a sequence suffix,
                // so return -1.
            } catch (NumberFormatException e) {
                LOG.info("Number format exception for " + idx, e);
            } catch (ArrayIndexOutOfBoundsException e) {
               LOG.info("Array out of bounds for " + idx, e);
            }
        }
    }

    @Override
    public String toString() {
        return name.toString();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        ZNodeName sequence = (ZNodeName) o;

        if (!name.equals(sequence.name)) return false;

        return true;
    }

    @Override
    public int hashCode() {
        return name.hashCode() + 37;
    }

    /**
     * Compare znodes based on their sequence number
     * @param that other znode to compare to
     * @return the difference between their sequence numbers: a positive value if this
     *         znode has a larger sequence number, 0 if they have the same sequence number
     *         or a negative number if this znode has a lower sequence number
     */
    public int compareTo(ZNodeName that) {
        int answer = this.sequence - that.sequence;
        if (answer == 0) {
            return this.prefix.compareTo(that.prefix);
        }
        return answer;
    }

    /**
     * Returns the name of the znode
     */
    public String getName() {
        return name;
    }

    /**
     * Returns the sequence number
     */
    public int getZNodeName() {
        return sequence;
    }

    /**
     * Returns the text prefix before the sequence number
     */
    public String getPrefix() {
        return prefix;
    }
}
