/**
    *    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.Statement;
  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.session.ExecutorType;
  import org.apache.ibatis.session.RowBounds;
  
  /**
   * @author Clinton Begin
   * @author Jeff Butler
   */
  public class SelectKeyGenerator implements KeyGenerator {
    
    public static final String SELECT_KEY_SUFFIX = "!selectKey";
    private boolean executeBefore;
    private MappedStatement keyStatement;
  
    public SelectKeyGenerator(MappedStatement keyStatement, boolean executeBefore) {
      this.executeBefore = executeBefore;
      this.keyStatement = keyStatement;
    }
  
    @Override
    public void processBefore(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
      if (executeBefore) {
        processGeneratedKeys(executor, ms, parameter);
      }
    }
  
    @Override
    public void processAfter(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
      if (!executeBefore) {
        processGeneratedKeys(executor, ms, parameter);
      }
    }
  
    private void processGeneratedKeys(Executor executor, MappedStatement ms, Object parameter) {
      try {
        if (parameter != null && keyStatement != null && keyStatement.getKeyProperties() != null) {
          String[] keyProperties = keyStatement.getKeyProperties();
          final Configuration configuration = ms.getConfiguration();
          final MetaObject metaParam = configuration.newMetaObject(parameter);
          if (keyProperties != null) {
            // Do not close keyExecutor.
            // The transaction will be closed by parent executor.
            Executor keyExecutor = configuration.newExecutor(executor.getTransaction(), ExecutorType.SIMPLE);
            List<Object> values = keyExecutor.query(keyStatement, parameter, RowBounds.DEFAULT, Executor.NO_RESULT_HANDLER);
            if (values.size() == 0) {
              throw new ExecutorException("SelectKey returned no data.");            
            } else if (values.size() > 1) {
              throw new ExecutorException("SelectKey returned more than one value.");
            } else {
              MetaObject metaResult = configuration.newMetaObject(values.get(0));
              if (keyProperties.length == 1) {
                if (metaResult.hasGetter(keyProperties[0])) {
                  setValue(metaParam, keyProperties[0], metaResult.getValue(keyProperties[0]));
                } else {
                  // no getter for the property - maybe just a single value object
                  // so try that
                  setValue(metaParam, keyProperties[0], values.get(0));
                }
              } else {
                handleMultipleProperties(keyProperties, metaParam, metaResult);
              }
            }
          }
        }
      } catch (ExecutorException e) {
        throw e;
      } catch (Exception e) {
        throw new ExecutorException("Error selecting key or setting result to parameter object. Cause: " + e, e);
      }
    }
  
    private void handleMultipleProperties(String[] keyProperties,
        MetaObject metaParam, MetaObject metaResult) {
      String[] keyColumns = keyStatement.getKeyColumns();
        
     if (keyColumns == null || keyColumns.length == 0) {
       // no key columns specified, just use the property names
       for (int i = 0; i < keyProperties.length; i++) {
         setValue(metaParam, keyProperties[i], metaResult.getValue(keyProperties[i]));
       }
     } else {
       if (keyColumns.length != keyProperties.length) {
         throw new ExecutorException("If SelectKey has key columns, the number must match the number of key properties.");
       }
       for (int i = 0; i < keyProperties.length; i++) {
         setValue(metaParam, keyProperties[i], metaResult.getValue(keyColumns[i]));
       }
     }
   }
 
   private void setValue(MetaObject metaParam, String property, Object value) {
     if (metaParam.hasSetter(property)) {
       metaParam.setValue(property, value);
     } else {
       throw new ExecutorException("No setter found for the keyProperty '" + property + "' in " + metaParam.getOriginalObject().getClass().getName() + ".");
     }
   }
 }