/*
    * Copyright 2004-2025 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.mapping.result.loader;
  
  import com.ibatis.common.beans.ClassInfo;
  import com.ibatis.sqlmap.engine.impl.SqlMapClientImpl;
  import com.ibatis.sqlmap.engine.type.DomTypeMarker;
  
  import java.sql.SQLException;
  import java.util.Collection;
  import java.util.List;
  import java.util.Set;
  
  import net.sf.cglib.proxy.Enhancer;
  import net.sf.cglib.proxy.LazyLoader;
  import net.sf.cglib.proxy.NoOp;
  
  /**
   * Class to lazily load results into objects (uses CGLib to improve performance).
   */
  public class EnhancedLazyResultLoader {
  
    /** The Constant SET_INTERFACES. */
    private static final Class[] SET_INTERFACES = { Set.class };
  
    /** The Constant LIST_INTERFACES. */
    private static final Class[] LIST_INTERFACES = { List.class };
  
    /** The loader. */
    private Object loader;
  
    /**
     * Constructor for an enhanced lazy list loader.
     *
     * @param client
     *          - the client that is creating the lazy list
     * @param statementName
     *          - the statement to be used to build the list
     * @param parameterObject
     *          - the parameter object to be used to build the list
     * @param targetType
     *          - the type we are putting data into
     */
    public EnhancedLazyResultLoader(SqlMapClientImpl client, String statementName, Object parameterObject,
        Class targetType) {
      loader = new EnhancedLazyResultLoaderImpl(client, statementName, parameterObject, targetType);
    }
  
    /**
     * Loads the result.
     *
     * @return the results - a list or object
     *
     * @throws SQLException
     *           if there is a problem
     */
    public Object loadResult() throws SQLException {
      return ((EnhancedLazyResultLoaderImpl) loader).loadResult();
    }
  
    /**
     * The Class EnhancedLazyResultLoaderImpl.
     */
    private static class EnhancedLazyResultLoaderImpl implements LazyLoader {
  
      /** The client. */
      protected SqlMapClientImpl client;
  
      /** The statement name. */
      protected String statementName;
  
      /** The parameter object. */
      protected Object parameterObject;
  
      /** The target type. */
      protected Class targetType;
  
      /**
       * Constructor for an enhanced lazy list loader implementation.
       *
       * @param client
       *          - the client that is creating the lazy list
       * @param statementName
       *          - the statement to be used to build the list
       * @param parameterObject
       *          - the parameter object to be used to build the list
      * @param targetType
      *          - the type we are putting data into
      */
     public EnhancedLazyResultLoaderImpl(SqlMapClientImpl client, String statementName, Object parameterObject,
         Class targetType) {
       this.client = client;
       this.statementName = statementName;
       this.parameterObject = parameterObject;
       this.targetType = targetType;
     }
 
     /**
      * Loads the result.
      *
      * @return the results - a list or object
      *
      * @throws SQLException
      *           if there is a problem
      */
     public Object loadResult() throws SQLException {
       if (DomTypeMarker.class.isAssignableFrom(targetType)) {
         return ResultLoader.getResult(client, statementName, parameterObject, targetType);
       }
       if (Collection.class.isAssignableFrom(targetType)) {
         if (Set.class.isAssignableFrom(targetType)) {
           return Enhancer.create(Object.class, SET_INTERFACES, this);
         }
         return Enhancer.create(Object.class, LIST_INTERFACES, this);
       }
       if (targetType.isArray() || ClassInfo.isKnownType(targetType)) {
         return ResultLoader.getResult(client, statementName, parameterObject, targetType);
       }
       return Enhancer.create(targetType, this);
     }
 
     @Override
     public Object loadObject() throws Exception {
       try {
         Object result = ResultLoader.getResult(client, statementName, parameterObject, targetType);
         if (result == null) {
           // if no result is available return a proxy with a default object is returned
           // because the loadObject() method must not return null
           result = Enhancer.create(targetType, NoOp.INSTANCE);
         }
         return result;
       } catch (SQLException e) {
         throw new RuntimeException("Error lazy loading result. Cause: " + e, e);
       }
     }
   }
 
 }