/*
    * Copyright 2009-2013 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 com.orangesignal.csv.handlers;
  
  import java.io.IOException;
  import java.sql.ResultSet;
  import java.sql.ResultSetMetaData;
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.List;
  
  import com.orangesignal.csv.CsvHandler;
  import com.orangesignal.csv.CsvReader;
  import com.orangesignal.csv.CsvResultSet;
  import com.orangesignal.csv.CsvWriter;
  
  /**
   * データベースの結果セットで区切り文字形式データアクセスを行うハンドラを提供します。
   *
   * @author Koji Sugisawa
   */
  public class ResultSetHandler implements CsvHandler<ResultSet> {
  
  	/**
  	 * 区切り文字形式データの列見出し (ヘッダ) 行を出力するかどうかを保持します。
  	 * 
  	 * @since 2.1
  	 */
  	private boolean header = true;
  
  	/**
  	 * デフォルトコンストラクタです。
  	 */
  	public ResultSetHandler() {
  	}
  
  	/**
  	 * 区切り文字形式データの列見出し (ヘッダ) 行を出力するかどうかを設定します。
  	 * 
  	 * @param header 区切り文字形式データの列見出し (ヘッダ) 行を出力するかどうか
  	 * @return このオブジェクトへの参照
  	 * @since 2.1
  	 */
  	public ResultSetHandler header(final boolean header) {
  		this.header = header;
  		return this;
  	}
  
  	@Override
  	public ResultSet load(final CsvReader reader) throws IOException {
  		return new CsvResultSet(reader);
  	}
  
  	@Override
  	public void save(final ResultSet rs, final CsvWriter writer) throws IOException {
  		try {
  			final int count = writeHeader(rs.getMetaData(), writer);
  			while (rs.next()) {
  				final List<String> list = new ArrayList<String>(count);
  				for (int i = 1; i <= count; i++) {
  					final Object o = rs.getObject(i);
  					if (rs.wasNull()) {
  						list.add(null);
  					} else {
  						list.add(o.toString());
  					}
  				}
  				writer.writeValues(list);
  			}
  		} catch (SQLException e) {
  			throw new IOException(e.getMessage(), e);
  		}
  	}
  
  	private int writeHeader(final ResultSetMetaData meta, final CsvWriter writer) throws IOException {
  		try {
  			final int count = meta.getColumnCount();
  			final List<String> list = new ArrayList<String>(count);
  			for (int i = 1; i <= count; i++) {
  				list.add(meta.getColumnLabel(i));
  			}
  			if (header) {
  				writer.writeValues(list);
  			}
  			return count;
 		} catch (SQLException e) {
 			throw new IOException(e.getMessage(), e);
 		}
 	}
 
 }