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/**
 * eobjects.org MetaModel
 * Copyright (C) 2010 eobjects.org
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.eobjects.metamodel.csv;

import java.io.BufferedReader;
import java.io.IOException;

import org.eobjects.metamodel.MetaModelException;
import org.eobjects.metamodel.data.AbstractDataSet;
import org.eobjects.metamodel.data.DataSetHeader;
import org.eobjects.metamodel.data.Row;
import org.eobjects.metamodel.schema.Column;
import org.eobjects.metamodel.util.FileHelper;

import au.com.bytecode.opencsv.CSVParser;

/**
 * A specialized DataSet implementation for the CSV module under circumstances
 * where multiline values are disabled. In this case we can use a optimized
 * CSVParser and also lazy evaluate lines read from the file.
 */
final class SingleLineCsvDataSet extends AbstractDataSet {

    private final BufferedReader _reader;
    private final CSVParser _csvParser;
    private final int _columnsInTable;
    private final boolean _failOnInconsistentRowLength;

    private volatile int _rowNumber;
    private volatile Integer _rowsRemaining;
    private volatile Row _row;

    public SingleLineCsvDataSet(BufferedReader reader, CSVParser csvParser, Column[] columns, Integer maxRows,
            int columnsInTable, boolean failOnInconsistentRowLength) {
        super(columns);
        _reader = reader;
        _csvParser = csvParser;
        _columnsInTable = columnsInTable;
        _failOnInconsistentRowLength = failOnInconsistentRowLength;
        _rowNumber = 0;
        _rowsRemaining = maxRows;
    }

    @Override
    public void close() {
        FileHelper.safeClose(_reader);
        _row = null;
        _rowsRemaining = null;
    }

    @Override
    public boolean next() {
        if (_rowsRemaining != null && _rowsRemaining > 0) {
            _rowsRemaining--;
            return nextInternal();
        } else if (_rowsRemaining == null) {
            return nextInternal();
        } else {
            return false;
        }
    }

    @Override
    protected DataSetHeader getHeader() {
        // re-make this method protected so that it's visible for
        // SingleLineCsvRow.
        return super.getHeader();
    }

    protected boolean isFailOnInconsistentRowLength() {
        return _failOnInconsistentRowLength;
    }

    protected int getColumnsInTable() {
        return _columnsInTable;
    }

    protected CSVParser getCsvParser() {
        return _csvParser;
    }

    public boolean nextInternal() {
        if (_reader == null) {
            return false;
        }

        try {
            final String line = _reader.readLine();
            if (line == null) {
                close();
                return false;
            }

            _rowNumber++;
            _row = new SingleLineCsvRow(this, line, _columnsInTable, _failOnInconsistentRowLength, _rowNumber);
            return true;
        } catch (IOException e) {
            close();
            throw new MetaModelException("IOException occurred while reading next line of CSV resource", e);
        }
    }

    @Override
    public Row getRow() {
        return _row;
    }

}