/*

* Copyright 2009-2014 the original author or authors.

*

* 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.yoiojava.cache;

import java.io.Serializable;

import java.lang.reflect.Array;

import java.util.ArrayList;

import java.util.List;

/**

* @author Clinton Begin

*/

public class CacheKey implements Cloneable, Serializable {

private static final long serialVersionUID = 1146682552656046210L;

public static final CacheKey NULL_CACHE_KEY = new NullCacheKey();

private static final int DEFAULT_MULTIPLYER = 37;

private static final int DEFAULT_HASHCODE = 17;

private int multiplier;

private int hashcode;

private long checksum;

private int count;

private List<Object> updateList;

public CacheKey() {

this.hashcode = DEFAULT_HASHCODE;

this.multiplier = DEFAULT_MULTIPLYER;

this.count = 0;

this.updateList = new ArrayList<Object>();

}

public CacheKey(Object[] objects) {

this();

updateAll(objects);

}

public int getUpdateCount() {

return updateList.size();

}

public void update(Object object) {

if (object != null && object.getClass().isArray()) {

int length = Array.getLength(object);

for (int i = 0; i < length; i++) {

Object element = Array.get(object, i);

doUpdate(element);

}

} else {

doUpdate(object);

}

}

private void doUpdate(Object object) {

int baseHashCode = object == null ? 1 : object.hashCode();

count++;

checksum += baseHashCode;

baseHashCode *= count;

hashcode = multiplier * hashcode + baseHashCode;

updateList.add(object);

}

public void updateAll(Object[] objects) {

for (Object o : objects) {

update(o);

}

}

@Override

public boolean equals(Object object) {

if (this == object) {

return true;

}

if (!(object instanceof CacheKey)) {

return false;

}

final CacheKey cacheKey = (CacheKey) object;

if (hashcode != cacheKey.hashcode) {

return false;

}

if (checksum != cacheKey.checksum) {

return false;

}

if (count != cacheKey.count) {

return false;

}

for (int i = 0; i < updateList.size(); i++) {

Object thisObject = updateList.get(i);

Object thatObject = cacheKey.updateList.get(i);

if (thisObject == null) {

if (thatObject != null) {

return false;

}

} else {

if (!thisObject.equals(thatObject)) {

return false;

}

}

}

return true;

}

@Override

public int hashCode() {

return hashcode;

}

@Override

public String toString() {

StringBuilder returnValue = new StringBuilder().append(hashcode).append(':').append(checksum);

for (int i = 0; i < updateList.size(); i++) {

returnValue.append(':').append(updateList.get(i));

}

return returnValue.toString();

}

@Override

public CacheKey clone() throws CloneNotSupportedException {

CacheKey clonedCacheKey = (CacheKey) super.clone();

clonedCacheKey.updateList = new ArrayList<Object>(updateList);

return clonedCacheKey;

}

}