<?php
/**
 * Copyright 2009-2017 Horde LLC (http://www.horde.org/)
 *
 * See the enclosed file COPYING for license information (LGPL). If you
 * did not receive this file, see http://www.horde.org/licenses/lgpl21.
 *
 * @author   Chuck Hagenbuch <chuck@horde.org>
 * @category Horde
 * @license  http://www.horde.org/licenses/lgpl21 LGPL
 * @package  Date
 */

/**
 * Date repeater.
 *
 * @author    Chuck Hagenbuch <chuck@horde.org>
 * @category  Horde
 * @copyright 2009-2017 Horde LLC
 * @license   http://www.horde.org/licenses/lgpl21 LGPL
 * @package   Date
 */
abstract class Horde_Date_Repeater
{
    public $now;

    /**
     * returns the width (in seconds or months) of this repeatable.
     */
    abstract public function width();

    /**
     * returns the next occurance of this repeatable.
     */
    public function next($pointer = 'future')
    {
        if (is_null($this->now)) {
            throw new Horde_Date_Repeater_Exception('Start point must be set before calling next()');
        }

        if (!in_array($pointer, array('future', 'none', 'past'))) {
            throw new Horde_Date_Repeater_Exception("First argument 'pointer' must be one of 'past', 'future', 'none'");
        }
    }

    public function this($pointer = 'future')
    {
        if (is_null($this->now)) {
            throw new Horde_Date_Repeater_Exception('Start point must be set before calling this()');
        }

        if (!in_array($pointer, array('future', 'none', 'past'))) {
            throw new Horde_Date_Repeater_Exception("First argument 'pointer' must be one of 'past', 'future', 'none'");
        }
    }

    public function __toString()
    {
        return 'repeater';
    }

}