/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.nio.model;

import java.util.Date;

import com.rapidminer.operator.OperatorException;
import com.rapidminer.tools.Ontology;
import com.rapidminer.tools.ProgressListener;
/**
 * This interface represents a ResultSet like view on a data source.
 * It is just the interface for iterating over the raw data. The 
 * 
 * @author Tobias Malbrecht, Sebastian Loh, Sebastian Land
 */
public interface DataResultSet {

	public enum ValueType {
		STRING(Ontology.POLYNOMINAL),
		DATE(Ontology.DATE_TIME),
		//INTEGER(Ontology.INTEGER),
		NUMBER(Ontology.NUMERICAL),
		EMPTY(Ontology.ATTRIBUTE_VALUE);
		
		private final int rapidMinerAttributeType;
		private ValueType(int rapidMinerAttributeType) {
			this.rapidMinerAttributeType = rapidMinerAttributeType;
		}
		public int getRapidMinerAttributeType() {
			return rapidMinerAttributeType;
		}
	}
	
	/**
	 * This returns if another row exists.
	 */
	public boolean hasNext();
	
	/**
	 * Proceed to the next row if existent. Will throw NoSuchElementException if no further row exists
	 * @param listener 
	 * 
	 * @return
	 */
	public void next(ProgressListener listener) throws OperatorException;

	/**
	 * Returns the number of columns found so far. If there are any rows containing
	 * more columns that this value, an error has to be registered.

	 */
	public int getNumberOfColumns();

	/**
	 * This returns the names of the columns according to the underlying technical system. For
	 * example the database column name might be returned.
	 * This method is only used, if there's no user specific setting in the {@link DataResultSetTranslationConfiguration} or annotations
	 * present in the {@link DataResultSetTranslationConfiguration}. 
	 */
	public String[] getColumnNames();
	
	/**
	 * Returns whether the value in the specified column in the current row is missing.
	 * 
	 * @param columnIndex
	 *            index of the column
	 * @return
	 */
	public boolean isMissing(int columnIndex);

	/**
	 * Returns a numerical value contained in the specified column in the current row. Should return null if the
	 * value is not a numerical or if the value is missing.
	 * 
	 * @param columnIndex
	 * @return
	 * @throws ParseException 
	 */
	public abstract Number getNumber(int columnIndex) throws ParseException;

	/**
	 * Returns a nominal value contained in the specified column in the current row. Should return null if the value
	 * is not a nominal or a kind of string type or if the value is missing.
	 * 
	 * @param columnIndex
	 * @return
	 */
	public abstract String getString(int columnIndex) throws ParseException;

	/**
	 * Returns a date, time or date_time value contained in the specified column in the current row. Should return
	 * null if the value is not a date or time value or if the value is missing.
	 * 
	 * @param columnIndex
	 * @return
	 */
	public abstract Date getDate(int columnIndex) throws ParseException;

	/**
	 * 
	 * @return The type which most closely matches the value type of the underlying data source.
	 *   The corresponding getter method for this type must not throw an RuntimeException when
	 *   invoked for this column. 
	 */
	public ValueType getNativeValueType(int columnIndex) throws ParseException;
	
	/**
	 * Closes the data source. May tear down a database connection or close a file which is read from.
	 * The underlying {@link DataResultSetFactory} may choose to keep the connection open for performance
	 * reasons and must be closed independently.
	 * 
	 * @throws OperatorException
	 */
	public abstract void close() throws OperatorException;

	/**
	 * This will reset the current iteration and start at the first row
	 * @param listener 
	 * @throws OperatorException 
	 */
	public void reset(ProgressListener listener) throws OperatorException;

	/**
	 * This will return an integer array containing the value types of all columns. This might be determined by
	 * the underlying technical system like data bases. If not, just an Array Containing 0 might be returned.
	 */
	public int[] getValueTypes();

	public int getCurrentRow();

}