/*
    *    Copyright 2009-2021 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 org.apache.ibatis.cache.decorators;
  
  import java.util.concurrent.TimeUnit;
  
  import org.apache.ibatis.cache.Cache;
  
  /**
   * @author Clinton Begin
   */
  public class ScheduledCache implements Cache {
  
    private final Cache delegate;
    protected long clearInterval;
    protected long lastClear;
  
    public ScheduledCache(Cache delegate) {
      this.delegate = delegate;
      this.clearInterval = TimeUnit.HOURS.toMillis(1);
      this.lastClear = System.currentTimeMillis();
    }
  
    public void setClearInterval(long clearInterval) {
      this.clearInterval = clearInterval;
    }
  
    @Override
    public String getId() {
      return delegate.getId();
    }
  
    @Override
    public int getSize() {
      clearWhenStale();
      return delegate.getSize();
    }
  
    @Override
    public void putObject(Object key, Object object) {
      clearWhenStale();
      delegate.putObject(key, object);
    }
  
    @Override
    public Object getObject(Object key) {
      return clearWhenStale() ? null : delegate.getObject(key);
    }
  
    @Override
    public Object removeObject(Object key) {
      clearWhenStale();
      return delegate.removeObject(key);
    }
  
    @Override
    public void clear() {
      lastClear = System.currentTimeMillis();
      delegate.clear();
    }
  
    @Override
    public int hashCode() {
      return delegate.hashCode();
    }
  
    @Override
    public boolean equals(Object obj) {
      return delegate.equals(obj);
    }
  
    private boolean clearWhenStale() {
      if (System.currentTimeMillis() - lastClear > clearInterval) {
        clear();
        return true;
      }
      return false;
    }
  
  }