package com.opencsv;
   
   /*
    * Copyright 2015 Scott Conway
    * 
    * 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.
   */
  
  import org.apache.commons.lang3.ArrayUtils;
  import org.apache.commons.lang3.ObjectUtils;
  import org.apache.commons.lang3.StringUtils;
  
  import java.io.IOException;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.util.*;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  /**
   * Helper class for processing JDBC ResultSet objects allowing the user to
   * process a subset of columns and set custom header names.
   */
  public class ResultSetColumnNameHelperService extends ResultSetHelperService implements ResultSetHelper {
      private String[] columnNames;
      private String[] columnHeaders;
      private final Map<String, Integer> columnNamePositionMap = new HashMap<>();
      private Locale errorLocale = Locale.getDefault();
  
      /**
       * Nullary constructor.
       */
      public ResultSetColumnNameHelperService() {
      }
      
      /**
       * Sets the locale for error messages.
       * @param errorLocale Locale for error messages. If null, the default locale
       *   is used.
       * @since 4.0
       */
      public void setErrorLocale(Locale errorLocale) {
          this.errorLocale = ObjectUtils.defaultIfNull(errorLocale, Locale.getDefault());
      }
      
      /**
       * Set the JDBC column names to use, and the header text for the CSV file
       * @param columnNames The JDBC column names to export, in the desired order
       * @param columnHeaders The column headers of the CSV file, in the desired order
       * @throws UnsupportedOperationException If the number of headers is different
       * than the number of columns, or if any of the columns or headers is blank
       * or null.
       */
      public void setColumnNames(String[] columnNames, String[] columnHeaders) {
          if (columnHeaders.length != columnNames.length) {
              throw new UnsupportedOperationException(ResourceBundle.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale).getString("column.count.mismatch"));
          }
          if (hasInvalidValue(columnNames)) {
              throw new UnsupportedOperationException(ResourceBundle.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale).getString("column.name.bogus"));
          }
          if (hasInvalidValue(columnHeaders)) {
              throw new UnsupportedOperationException(ResourceBundle.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale).getString("header.name.bogus"));
          }
          this.columnNames = Arrays.copyOf(columnNames, columnNames.length);
          this.columnHeaders = Arrays.copyOf(columnHeaders, columnHeaders.length);
      }
  
      private boolean hasInvalidValue(String[] strings) {
          return Stream.of(strings).anyMatch(s -> StringUtils.isBlank(s));
      }
  
      /**
       * Returns the column names from the result set.
       * @param rs ResultSet
       * @return A string array containing the column names.
       * @throws SQLException Thrown by the result set.
       */
      @Override
      public String[] getColumnNames(ResultSet rs) throws SQLException {
          if (columnNamePositionMap.isEmpty()) {
              populateColumnData(rs);
          }
          return Arrays.copyOf(columnHeaders, columnHeaders.length);
      }
  
      private void populateColumnData(ResultSet rs) throws SQLException {
          String[] realColumnNames = super.getColumnNames(rs);
  
          if (columnNames == null) {
             columnNames = Arrays.copyOf(realColumnNames, realColumnNames.length);
             columnHeaders = Arrays.copyOf(realColumnNames, realColumnNames.length);
         }
 
         for (String name : columnNames) {
             int position = ArrayUtils.indexOf(realColumnNames, name);
             if (position == ArrayUtils.INDEX_NOT_FOUND) {
                 throw new UnsupportedOperationException(String.format(ResourceBundle.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale).getString("column.nonexistant"), name));
             }
             columnNamePositionMap.put(name, position);
         }
     }
 
     /**
      * Get all the column values from the result set.
      * @param rs The ResultSet containing the values.
      * @return String array containing all the column values.
      * @throws SQLException Thrown by the result set.
      * @throws IOException Thrown by the result set.
      */
     @Override
     public String[] getColumnValues(ResultSet rs) throws SQLException, IOException {
         if (columnNamePositionMap.isEmpty()) {
             populateColumnData(rs);
         }
         String[] realColumnValues = super.getColumnValues(rs, false, dateFormat, dateTimeFormat);
         return getColumnValueSubset(realColumnValues);
     }
 
     /**
      * Get all the column values from the result set.
      * @param rs The ResultSet containing the values.
      * @param trim Values should have white spaces trimmed.
      * @return String array containing all the column values.
      * @throws SQLException Thrown by the result set.
      * @throws IOException Thrown by the result set.
      */
     @Override
     public String[] getColumnValues(ResultSet rs, boolean trim) throws SQLException, IOException {
         if (columnNamePositionMap.isEmpty()) {
             populateColumnData(rs);
         }
         String[] realColumnValues = super.getColumnValues(rs, trim, dateFormat, dateTimeFormat);
         return getColumnValueSubset(realColumnValues);
     }
 
     /**
      * Get all the column values from the result set.
      * @param rs The ResultSet containing the values.
      * @param trim Values should have white spaces trimmed.
      * @param dateFormatString Format string for dates.
      * @param timeFormatString Format string for timestamps.
      * @return String array containing all the column values.
      * @throws SQLException Thrown by the result set.
      * @throws IOException Thrown by the result set.
      */
     @Override
     public String[] getColumnValues(ResultSet rs, boolean trim, String dateFormatString, String timeFormatString) throws SQLException, IOException {
         if (columnNamePositionMap.isEmpty()) {
             populateColumnData(rs);
         }
         String[] realColumnValues = super.getColumnValues(rs, trim, dateFormatString, timeFormatString);
         return getColumnValueSubset(realColumnValues);
     }
 
     private String[] getColumnValueSubset(String[] realColumnValues) {
         return Stream.of(columnNames)
                 .map(c -> realColumnValues[columnNamePositionMap.get(c)])
                 .collect(Collectors.toList())
                 .toArray(ArrayUtils.EMPTY_STRING_ARRAY);
     }
 }