/**
    *    Copyright 2009-2015 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.executor;
  
  import java.sql.SQLException;
  import java.util.List;
  
  import org.apache.ibatis.cache.Cache;
  import org.apache.ibatis.cache.CacheKey;
  import org.apache.ibatis.cache.TransactionalCacheManager;
  import org.apache.ibatis.mapping.BoundSql;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.mapping.ParameterMapping;
  import org.apache.ibatis.mapping.ParameterMode;
  import org.apache.ibatis.mapping.StatementType;
  import org.apache.ibatis.reflection.MetaObject;
  import org.apache.ibatis.session.ResultHandler;
  import org.apache.ibatis.session.RowBounds;
  import org.apache.ibatis.transaction.Transaction;
  
  /**
   * @author Clinton Begin
   * @author Eduardo Macarron
   */
  public class CachingExecutor implements Executor {
  
    private Executor delegate;
    private TransactionalCacheManager tcm = new TransactionalCacheManager();
  
    public CachingExecutor(Executor delegate) {
      this.delegate = delegate;
      delegate.setExecutorWrapper(this);
    }
  
    @Override
    public Transaction getTransaction() {
      return delegate.getTransaction();
    }
  
    @Override
    public void close(boolean forceRollback) {
      try {
        //issues #499, #524 and #573
        if (forceRollback) { 
          tcm.rollback();
        } else {
          tcm.commit();
        }
      } finally {
        delegate.close(forceRollback);
      }
    }
  
    @Override
    public boolean isClosed() {
      return delegate.isClosed();
    }
  
    @Override
    public int update(MappedStatement ms, Object parameterObject) throws SQLException {
      flushCacheIfRequired(ms);
      return delegate.update(ms, parameterObject);
    }
  
    @Override
    public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException {
      BoundSql boundSql = ms.getBoundSql(parameterObject);
      CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);
      return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
    }
  
    @Override
    public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
        throws SQLException {
      Cache cache = ms.getCache();
      if (cache != null) {
        flushCacheIfRequired(ms);
        if (ms.isUseCache() && resultHandler == null) {
          ensureNoOutParams(ms, parameterObject, boundSql);
          @SuppressWarnings("unchecked")
          List<E> list = (List<E>) tcm.getObject(cache, key);
          if (list == null) {
            list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
            tcm.putObject(cache, key, list); // issue #578 and #116
          }
          return list;
       }
     }
     return delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
   }
 
   @Override
   public List<BatchResult> flushStatements() throws SQLException {
     return delegate.flushStatements();
   }
 
   @Override
   public void commit(boolean required) throws SQLException {
     delegate.commit(required);
     tcm.commit();
   }
 
   @Override
   public void rollback(boolean required) throws SQLException {
     try {
       delegate.rollback(required);
     } finally {
       if (required) {
         tcm.rollback();
       }
     }
   }
 
   private void ensureNoOutParams(MappedStatement ms, Object parameter, BoundSql boundSql) {
     if (ms.getStatementType() == StatementType.CALLABLE) {
       for (ParameterMapping parameterMapping : boundSql.getParameterMappings()) {
         if (parameterMapping.getMode() != ParameterMode.IN) {
           throw new ExecutorException("Caching stored procedures with OUT params is not supported.  Please configure useCache=false in " + ms.getId() + " statement.");
         }
       }
     }
   }
 
   @Override
   public CacheKey createCacheKey(MappedStatement ms, Object parameterObject, RowBounds rowBounds, BoundSql boundSql) {
     return delegate.createCacheKey(ms, parameterObject, rowBounds, boundSql);
   }
 
   @Override
   public boolean isCached(MappedStatement ms, CacheKey key) {
     return delegate.isCached(ms, key);
   }
 
   @Override
   public void deferLoad(MappedStatement ms, MetaObject resultObject, String property, CacheKey key, Class<?> targetType) {
     delegate.deferLoad(ms, resultObject, property, key, targetType);
   }
 
   @Override
   public void clearLocalCache() {
     delegate.clearLocalCache();
   }
 
   private void flushCacheIfRequired(MappedStatement ms) {
     Cache cache = ms.getCache();
     if (cache != null && ms.isFlushCacheRequired()) {      
       tcm.clear(cache);
     }
   }
 
   @Override
   public void setExecutorWrapper(Executor executor) {
     throw new UnsupportedOperationException("This method should not be called");
   }
 
 }