/*
    * Copyright 2004-2023 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 com.ibatis.common.logging.Log;
  import com.ibatis.common.logging.LogFactory;
  import com.ibatis.sqlmap.engine.mapping.statement.ExecuteListener;
  import com.ibatis.sqlmap.engine.mapping.statement.MappedStatement;
  
  import java.io.*;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Properties;
  import java.util.Set;
  
  /**
   * Wrapper for Caches.
   */
  public class CacheModel implements ExecuteListener {
  
    /** The Constant log. */
    private static final Log log = LogFactory.getLog(CacheModel.class);
  
    /** The Constant MAX_OBJECT_LOG_SIZE. */
    private static final int MAX_OBJECT_LOG_SIZE = 200;
  
    /**
     * This is used to represent null objects that are returned from the cache so that they can be cached, too.
     */
    public static final Object NULL_OBJECT = "SERIALIZABLE_NULL_OBJECT";
  
    /** The requests. */
    private int requests = 0;
  
    /** The hits. */
    private int hits = 0;
  
    /** Constant to turn off periodic cache flushes. */
    private static final long NO_FLUSH_INTERVAL = -99999;
  
    /** The id. */
    private String id;
  
    /** The read only. */
    private boolean readOnly;
  
    /** The serialize. */
    private boolean serialize;
  
    /** The last flush. */
    private long lastFlush;
  
    /** The flush interval. */
    private long flushInterval;
  
    /** The flush interval seconds. */
    private long flushIntervalSeconds;
  
    /** The flush trigger statements. */
    private Set flushTriggerStatements;
  
    /** The controller. */
    private CacheController controller;
  
    /** The resource. */
    private String resource;
  
    /**
     * Default constructor.
     */
    public CacheModel() {
      this.flushInterval = NO_FLUSH_INTERVAL;
      this.flushIntervalSeconds = NO_FLUSH_INTERVAL;
      this.lastFlush = System.currentTimeMillis();
      this.flushTriggerStatements = new HashSet();
    }
  
    /**
     * Getter for the cache model's id.
     *
     * @return the id
     */
    public String getId() {
      return id;
    }
  
   /**
    * Setter for the cache model's id.
    *
    * @param id
    *          - the new id
    */
   public void setId(String id) {
     this.id = id;
   }
 
   /**
    * Getter for read-only property.
    *
    * @return true if a read-only model
    */
   public boolean isReadOnly() {
     return readOnly;
   }
 
   /**
    * Setter for read-only property.
    *
    * @param readOnly
    *          - the new setting
    */
   public void setReadOnly(boolean readOnly) {
     this.readOnly = readOnly;
   }
 
   /**
    * Getter to tell if the cache serializes.
    *
    * @return true if the cache model serializes objects
    */
   public boolean isSerialize() {
     return serialize;
   }
 
   /**
    * Setter to tell the cache to serialize objects.
    *
    * @param serialize
    *          - if the cache model is to serialize objects
    */
   public void setSerialize(boolean serialize) {
     this.serialize = serialize;
   }
 
   /**
    * Getter for resource property.
    *
    * @return the value of the resource property
    */
   public String getResource() {
     return resource;
   }
 
   /**
    * Setter for resource property.
    *
    * @param resource
    *          - the new value
    */
   public void setResource(String resource) {
     this.resource = resource;
   }
 
   /**
    * Sets up the controller for the cache model.
    *
    * @param controller
    *          the new cache controller
    *
    * @throws ClassNotFoundException
    *           - if the class cannot be found
    * @throws InstantiationException
    *           - if the class cannot be instantiated
    * @throws IllegalAccessException
    *           - if the classes constructor is not accessible
    */
   public void setCacheController(CacheController controller)
       throws ClassNotFoundException, InstantiationException, IllegalAccessException {
     this.controller = controller;
   }
 
   /**
    * Getter for flushInterval property.
    *
    * @return The flushInterval (in milliseconds)
    */
   public long getFlushInterval() {
     return flushInterval;
   }
 
   /**
    * Getter for flushInterval property.
    *
    * @return The flushInterval (in milliseconds)
    */
   public long getFlushIntervalSeconds() {
     return flushIntervalSeconds;
   }
 
   /**
    * Setter for flushInterval property.
    *
    * @param flushInterval
    *          The new flushInterval (in milliseconds)
    */
   public void setFlushInterval(long flushInterval) {
     this.flushInterval = flushInterval;
     this.flushIntervalSeconds = flushInterval / 1000;
   }
 
   /**
    * Adds a flushTriggerStatment. When a flushTriggerStatment is executed, the cache is flushed (cleared).
    *
    * @param statementName
    *          The statement to add.
    */
   public void addFlushTriggerStatement(String statementName) {
     flushTriggerStatements.add(statementName);
   }
 
   /**
    * Gets an Iterator containing all flushTriggerStatment objects for this cache.
    *
    * @return The Iterator
    */
   public Iterator getFlushTriggerStatementNames() {
     return flushTriggerStatements.iterator();
   }
 
   /**
    * ExecuteListener event. This will be called by a MappedStatement for which this cache is registered as a
    * ExecuteListener. It will be called each time an executeXXXXXX method is called. In the case of the Cache class, it
    * is registered in order to flush the cache whenever a certain statement is executed. (i.e. the flushOnExecute cache
    * policy)
    *
    * @param statement
    *          The statement to execute
    */
   public void onExecuteStatement(MappedStatement statement) {
     flush();
   }
 
   /**
    * Returns statistical information about the cache.
    *
    * @return the number of cache hits divided by the total requests
    */
   public double getHitRatio() {
     return (double) hits / (double) requests;
   }
 
   /**
    * Configures the cache.
    *
    * @param props
    *          the props
    */
   public void configure(Properties props) {
     controller.setProperties(props);
   }
 
   /**
    * Clears the cache.
    */
   public void flush() {
     synchronized (this) {
       controller.flush(this);
       lastFlush = System.currentTimeMillis();
       if (log.isDebugEnabled()) {
         log("flushed", false, null);
       }
     }
   }
 
   /**
    * Get an object out of the cache. A side effect of this method is that is may clear the cache if it has not been
    * cleared in the flushInterval.
    *
    * @param key
    *          The key of the object to be returned
    *
    * @return The cached object (or null)
    */
   public Object getObject(CacheKey key) {
     Object value = null;
     synchronized (this) {
       if (flushInterval != NO_FLUSH_INTERVAL && System.currentTimeMillis() - lastFlush > flushInterval) {
         flush();
       }
 
       value = controller.getObject(this, key);
       if (serialize && !readOnly && (value != NULL_OBJECT && value != null)) {
         try {
           ByteArrayInputStream bis = new ByteArrayInputStream((byte[]) value);
           ObjectInputStream ois = new ObjectInputStream(bis);
           value = ois.readObject();
           ois.close();
         } catch (Exception e) {
           throw new RuntimeException("Error caching serializable object.  Be sure you're not attempting to use "
               + "a serialized cache for an object that may be taking advantage of lazy loading.  Cause: " + e, e);
         }
       }
       requests++;
       if (value != null) {
         hits++;
       }
       if (log.isDebugEnabled()) {
         if (value != null) {
           log("retrieved object", true, value);
         } else {
           log("cache miss", false, null);
         }
       }
     }
     return value;
   }
 
   /**
    * Add an object to the cache.
    *
    * @param key
    *          The key of the object to be cached
    * @param value
    *          The object to be cached
    */
   public void putObject(CacheKey key, Object value) {
     if (null == value)
       value = NULL_OBJECT;
     synchronized (this) {
       if (serialize && !readOnly && value != NULL_OBJECT) {
         try {
           ByteArrayOutputStream bos = new ByteArrayOutputStream();
           ObjectOutputStream oos = new ObjectOutputStream(bos);
           oos.writeObject(value);
           oos.flush();
           oos.close();
           value = bos.toByteArray();
         } catch (IOException e) {
           throw new RuntimeException("Error caching serializable object.  Cause: " + e, e);
         }
       }
       controller.putObject(this, key, value);
       if (log.isDebugEnabled()) {
         log("stored object", true, value);
       }
     }
   }
 
   /**
    * Get the maximum size of an object in the log output.
    *
    * @return Maximum size of a logged object in the output
    */
   protected int getMaxObjectLogSize() {
     return MAX_OBJECT_LOG_SIZE;
   }
 
   /**
    * Log a cache action. Since this method is pretty heavy weight, it's best to enclose it with a log.isDebugEnabled()
    * when called.
    *
    * @param action
    *          String to output
    * @param addValue
    *          Add the value being cached to the log
    * @param cacheValue
    *          The value being logged
    */
   protected void log(String action, boolean addValue, Object cacheValue) {
     StringBuilder output = new StringBuilder("Cache '");
     output.append(getId());
     output.append("': ");
     output.append(action);
     if (addValue) {
       String cacheObjectStr = (cacheValue == null ? "null" : cacheValue.toString());
       output.append(" '");
       if (cacheObjectStr.length() < getMaxObjectLogSize()) {
         output.append(cacheObjectStr);
       } else {
         output.append(cacheObjectStr.substring(1, getMaxObjectLogSize()));
         output.append("...");
       }
       output.append("'");
     }
     log.debug(output.toString());
   }
 
   /**
    * Sets the controller properties.
    *
    * @param cacheProps
    *          the new controller properties
    */
   public void setControllerProperties(Properties cacheProps) {
     controller.setProperties(cacheProps);
   }
 }