/*
    * Copyright 2004-2026 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 java.lang.reflect.InvocationHandler;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Proxy;
  import java.sql.SQLException;
  import java.util.Collection;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Class to lazily load results into objects.
   */
  public class LazyResultLoader implements InvocationHandler {
  
    /** 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 client. */
    protected SqlMapClientImpl client;
  
    /** The statement name. */
    protected String statementName;
  
    /** The parameter object. */
    protected Object parameterObject;
  
    /** The target type. */
    protected Class targetType;
  
    /** The loaded. */
    protected boolean loaded;
  
    /** The result object. */
    protected Object resultObject;
  
    /**
     * Constructor for a 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 LazyResultLoader(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 (!Collection.class.isAssignableFrom(targetType)) {
        return ResultLoader.getResult(client, statementName, parameterObject, targetType);
      }
      InvocationHandler handler = new LazyResultLoader(client, statementName, parameterObject, targetType);
      ClassLoader cl = targetType.getClassLoader();
      if (Set.class.isAssignableFrom(targetType)) {
        return Proxy.newProxyInstance(cl, SET_INTERFACES, handler);
      }
      return Proxy.newProxyInstance(cl, LIST_INTERFACES, handler);
    }
  
    @Override
    public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
     if ("finalize".hashCode() == method.getName().hashCode() && "finalize".equals(method.getName())) {
       return null;
     }
     loadObject();
     if (resultObject == null) {
       return null;
     }
     try {
       return method.invoke(resultObject, objects);
     } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
       throw ClassInfo.unwrapThrowable(e);
     }
   }
 
   /**
    * Load object.
    */
   private synchronized void loadObject() {
     if (!loaded) {
       try {
         loaded = true;
         resultObject = ResultLoader.getResult(client, statementName, parameterObject, targetType);
       } catch (SQLException e) {
         throw new RuntimeException("Error lazy loading result. Cause: " + e, e);
       }
     }
   }
 
 }