<?php

namespace PhpOffice\PhpSpreadsheet\Worksheet;

/**
 * Copyright (c) 2006 - 2016 PhpSpreadsheet.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * @category   PhpSpreadsheet
 *
 * @copyright  Copyright (c) 2006 - 2016 PhpSpreadsheet (https://github.com/PHPOffice/PhpSpreadsheet)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 */
class Iterator implements \Iterator
{
    /**
     * Spreadsheet to iterate.
     *
     * @var \PhpOffice\PhpSpreadsheet\Spreadsheet
     */
    private $subject;

    /**
     * Current iterator position.
     *
     * @var int
     */
    private $position = 0;

    /**
     * Create a new worksheet iterator.
     *
     * @param \PhpOffice\PhpSpreadsheet\Spreadsheet $subject
     */
    public function __construct(\PhpOffice\PhpSpreadsheet\Spreadsheet $subject = null)
    {
        // Set subject
        $this->subject = $subject;
    }

    /**
     * Destructor.
     */
    public function __destruct()
    {
        unset($this->subject);
    }

    /**
     * Rewind iterator.
     */
    public function rewind()
    {
        $this->position = 0;
    }

    /**
     * Current Worksheet.
     *
     * @return \PhpOffice\PhpSpreadsheet\Worksheet
     */
    public function current()
    {
        return $this->subject->getSheet($this->position);
    }

    /**
     * Current key.
     *
     * @return int
     */
    public function key()
    {
        return $this->position;
    }

    /**
     * Next value.
     */
    public function next()
    {
        ++$this->position;
    }

    /**
     * Are there more Worksheet instances available?
     *
     * @return bool
     */
    public function valid()
    {
        return $this->position < $this->subject->getSheetCount();
    }
}