/*
    * Copyright 2004-2022 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
    *
    *    https://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.ibatis.sqlmap.engine.cache;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Hash value generator for cache keys.
   */
  public class CacheKey implements Cloneable, Serializable {
  
    /** The Constant DEFAULT_MULTIPLYER. */
    private static final int DEFAULT_MULTIPLYER = 37;
  
    /** The Constant DEFAULT_HASHCODE. */
    private static final int DEFAULT_HASHCODE = 17;
  
    /** The multiplier. */
    private int multiplier;
  
    /** The hashcode. */
    private int hashcode;
  
    /** The checksum. */
    private long checksum;
  
    /** The count. */
    private int count;
  
    /** The param list. */
    private List paramList = new ArrayList();
  
    /**
     * Default constructor.
     */
    public CacheKey() {
      hashcode = DEFAULT_HASHCODE;
      multiplier = DEFAULT_MULTIPLYER;
      count = 0;
    }
  
    /**
     * Constructor that supplies an initial hashcode.
     *
     * @param initialNonZeroOddNumber
     *          - the hashcode to use
     */
    public CacheKey(int initialNonZeroOddNumber) {
      hashcode = initialNonZeroOddNumber;
      multiplier = DEFAULT_MULTIPLYER;
      count = 0;
    }
  
    /**
     * Costructor that supplies an initial hashcode and multiplier.
     *
     * @param initialNonZeroOddNumber
     *          - the hashcode to use
     * @param multiplierNonZeroOddNumber
     *          - the multiplier to use
     */
    public CacheKey(int initialNonZeroOddNumber, int multiplierNonZeroOddNumber) {
      hashcode = initialNonZeroOddNumber;
      multiplier = multiplierNonZeroOddNumber;
      count = 0;
    }
  
    /**
     * Updates this object with new information based on an int value.
     *
     * @param x
     *          - the int value
     *
     * @return the cache key
     */
    public CacheKey update(int x) {
      update(Integer.valueOf(x));
      return this;
    }
  
    /**
     * Updates this object with new information based on an object.
     *
     * @param object
    *          - the object
    *
    * @return the cachekey
    */
   public CacheKey update(Object object) {
     int baseHashCode = object.hashCode();
 
     count++;
     checksum += baseHashCode;
     baseHashCode *= count;
 
     hashcode = multiplier * hashcode + baseHashCode;
 
     paramList.add(object);
 
     return this;
   }
 
   @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 < paramList.size(); i++) {
       Object thisParam = paramList.get(i);
       Object thatParam = cacheKey.paramList.get(i);
       if (thisParam == null) {
         if (thatParam != null)
           return false;
       } else {
         if (!thisParam.equals(thatParam))
           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 < paramList.size(); i++) {
       returnValue.append('|').append(paramList.get(i));
     }
 
     return returnValue.toString();
   }
 
   @Override
   public CacheKey clone() throws CloneNotSupportedException {
     CacheKey clonedCacheKey = (CacheKey) super.clone();
     clonedCacheKey.paramList = new ArrayList<Object>(paramList);
     return clonedCacheKey;
   }
 
 }