/**
    *    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.keygen;
  
  import java.sql.ResultSet;
  import java.sql.ResultSetMetaData;
  import java.sql.SQLException;
  import java.sql.Statement;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.ibatis.executor.Executor;
  import org.apache.ibatis.executor.ExecutorException;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.reflection.MetaObject;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.type.TypeHandler;
  import org.apache.ibatis.type.TypeHandlerRegistry;
  
  /**
   * @author Clinton Begin
   */
  public class Jdbc3KeyGenerator implements KeyGenerator {
  
    @Override
    public void processBefore(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
      // do nothing
    }
  
    @Override
    public void processAfter(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
      List<Object> parameters = new ArrayList<Object>();
      parameters.add(parameter);
      processBatch(ms, stmt, parameters);
    }
  
    public void processBatch(MappedStatement ms, Statement stmt, List<Object> parameters) {
      ResultSet rs = null;
      try {
        rs = stmt.getGeneratedKeys();
        final Configuration configuration = ms.getConfiguration();
        final TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
        final String[] keyProperties = ms.getKeyProperties();
        final ResultSetMetaData rsmd = rs.getMetaData();
        TypeHandler<?>[] typeHandlers = null;
        if (keyProperties != null && rsmd.getColumnCount() >= keyProperties.length) {
          for (Object parameter : parameters) {
            // there should be one row for each statement (also one for each parameter)
            if (!rs.next()) {
              break;
            }
            final MetaObject metaParam = configuration.newMetaObject(parameter);
            if (typeHandlers == null) {
              typeHandlers = getTypeHandlers(typeHandlerRegistry, metaParam, keyProperties);
            }
            populateKeys(rs, metaParam, keyProperties, typeHandlers);
          }
        }
      } catch (Exception e) {
        throw new ExecutorException("Error getting generated key or setting result to parameter object. Cause: " + e, e);
      } finally {
        if (rs != null) {
          try {
            rs.close();
          } catch (Exception e) {
            // ignore
          }
        }
      }
    }
  
    private TypeHandler<?>[] getTypeHandlers(TypeHandlerRegistry typeHandlerRegistry, MetaObject metaParam, String[] keyProperties) {
      TypeHandler<?>[] typeHandlers = new TypeHandler<?>[keyProperties.length];
      for (int i = 0; i < keyProperties.length; i++) {
        if (metaParam.hasSetter(keyProperties[i])) {
          Class<?> keyPropertyType = metaParam.getSetterType(keyProperties[i]);
          TypeHandler<?> th = typeHandlerRegistry.getTypeHandler(keyPropertyType);
          typeHandlers[i] = th;
        }
      }
      return typeHandlers;
    }
  
    private void populateKeys(ResultSet rs, MetaObject metaParam, String[] keyProperties, TypeHandler<?>[] typeHandlers) throws SQLException {
      for (int i = 0; i < keyProperties.length; i++) {
        TypeHandler<?> th = typeHandlers[i];
       if (th != null) {
         Object value = th.getResult(rs, i + 1);
         metaParam.setValue(keyProperties[i], value);
       }
     }
   }
 
 }