/**
    *    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.resultset;
  
  import java.sql.ResultSet;
  import java.sql.ResultSetMetaData;
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  import org.apache.ibatis.io.Resources;
  import org.apache.ibatis.mapping.ResultMap;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.type.JdbcType;
  import org.apache.ibatis.type.ObjectTypeHandler;
  import org.apache.ibatis.type.TypeHandler;
  import org.apache.ibatis.type.TypeHandlerRegistry;
  import org.apache.ibatis.type.UnknownTypeHandler;
  
  /**
   * @author Iwao AVE!
   */
  class ResultSetWrapper {
  
    private final ResultSet resultSet;
    private final TypeHandlerRegistry typeHandlerRegistry;
    private final List<String> columnNames = new ArrayList<String>();
    private final List<String> classNames = new ArrayList<String>();
    private final List<JdbcType> jdbcTypes = new ArrayList<JdbcType>();
    private final Map<String, Map<Class<?>, TypeHandler<?>>> typeHandlerMap = new HashMap<String, Map<Class<?>, TypeHandler<?>>>();
    private Map<String, List<String>> mappedColumnNamesMap = new HashMap<String, List<String>>();
    private Map<String, List<String>> unMappedColumnNamesMap = new HashMap<String, List<String>>();
  
    public ResultSetWrapper(ResultSet rs, Configuration configuration) throws SQLException {
      super();
      this.typeHandlerRegistry = configuration.getTypeHandlerRegistry();
      this.resultSet = rs;
      final ResultSetMetaData metaData = rs.getMetaData();
      final int columnCount = metaData.getColumnCount();
      for (int i = 1; i <= columnCount; i++) {
        columnNames.add(configuration.isUseColumnLabel() ? metaData.getColumnLabel(i) : metaData.getColumnName(i));
        jdbcTypes.add(JdbcType.forCode(metaData.getColumnType(i)));
        classNames.add(metaData.getColumnClassName(i));
      }
    }
  
    public ResultSet getResultSet() {
      return resultSet;
    }
  
    public List<String> getColumnNames() {
      return this.columnNames;
    }
  
    public List<String> getClassNames() {
      return Collections.unmodifiableList(classNames);
    }
  
    /**
     * Gets the type handler to use when reading the result set.
     * Tries to get from the TypeHandlerRegistry by searching for the property type.
     * If not found it gets the column JDBC type and tries to get a handler for it.
     * 
     * @param propertyType
     * @param columnName
     * @return
     */
    public TypeHandler<?> getTypeHandler(Class<?> propertyType, String columnName) {
      TypeHandler<?> handler = null;
      Map<Class<?>, TypeHandler<?>> columnHandlers = typeHandlerMap.get(columnName);
      if (columnHandlers == null) {
        columnHandlers = new HashMap<Class<?>, TypeHandler<?>>();
        typeHandlerMap.put(columnName, columnHandlers);
      } else {
        handler = columnHandlers.get(propertyType);
      }
      if (handler == null) {
        handler = typeHandlerRegistry.getTypeHandler(propertyType);
        // Replicate logic of UnknownTypeHandler#resolveTypeHandler
        // See issue #59 comment 10
        if (handler == null || handler instanceof UnknownTypeHandler) {
         final int index = columnNames.indexOf(columnName);
         final JdbcType jdbcType = jdbcTypes.get(index);
         final Class<?> javaType = resolveClass(classNames.get(index));
         if (javaType != null && jdbcType != null) {
           handler = typeHandlerRegistry.getTypeHandler(javaType, jdbcType);
         } else if (javaType != null) {
           handler = typeHandlerRegistry.getTypeHandler(javaType);
         } else if (jdbcType != null) {
           handler = typeHandlerRegistry.getTypeHandler(jdbcType);
         }
       }
       if (handler == null || handler instanceof UnknownTypeHandler) {
         handler = new ObjectTypeHandler();
       }
       columnHandlers.put(propertyType, handler);
     }
     return handler;
   }
 
   private Class<?> resolveClass(String className) {
     try {
       return Resources.classForName(className);
     } catch (ClassNotFoundException e) {
       return null;
     }
   }
 
   private void loadMappedAndUnmappedColumnNames(ResultMap resultMap, String columnPrefix) throws SQLException {
     List<String> mappedColumnNames = new ArrayList<String>();
     List<String> unmappedColumnNames = new ArrayList<String>();
     final String upperColumnPrefix = columnPrefix == null ? null : columnPrefix.toUpperCase(Locale.ENGLISH);
     final Set<String> mappedColumns = prependPrefixes(resultMap.getMappedColumns(), upperColumnPrefix);
     for (String columnName : columnNames) {
       final String upperColumnName = columnName.toUpperCase(Locale.ENGLISH);
       if (mappedColumns.contains(upperColumnName)) {
         mappedColumnNames.add(upperColumnName);
       } else {
         unmappedColumnNames.add(columnName);
       }
     }
     mappedColumnNamesMap.put(getMapKey(resultMap, columnPrefix), mappedColumnNames);
     unMappedColumnNamesMap.put(getMapKey(resultMap, columnPrefix), unmappedColumnNames);
   }
 
   public List<String> getMappedColumnNames(ResultMap resultMap, String columnPrefix) throws SQLException {
     List<String> mappedColumnNames = mappedColumnNamesMap.get(getMapKey(resultMap, columnPrefix));
     if (mappedColumnNames == null) {
       loadMappedAndUnmappedColumnNames(resultMap, columnPrefix);
       mappedColumnNames = mappedColumnNamesMap.get(getMapKey(resultMap, columnPrefix));
     }
     return mappedColumnNames;
   }
 
   public List<String> getUnmappedColumnNames(ResultMap resultMap, String columnPrefix) throws SQLException {
     List<String> unMappedColumnNames = unMappedColumnNamesMap.get(getMapKey(resultMap, columnPrefix));
     if (unMappedColumnNames == null) {
       loadMappedAndUnmappedColumnNames(resultMap, columnPrefix);
       unMappedColumnNames = unMappedColumnNamesMap.get(getMapKey(resultMap, columnPrefix));
     }
     return unMappedColumnNames;
   }
 
   private String getMapKey(ResultMap resultMap, String columnPrefix) {
     return resultMap.getId() + ":" + columnPrefix;
   }
 
   private Set<String> prependPrefixes(Set<String> columnNames, String prefix) {
     if (columnNames == null || columnNames.isEmpty() || prefix == null || prefix.length() == 0) {
       return columnNames;
     }
     final Set<String> prefixed = new HashSet<String>();
     for (String columnName : columnNames) {
       prefixed.add(prefix + columnName);
     }
     return prefixed;
   }
   
 }