<?php

/**
 *  PEL: PHP Exif Library.  A library with support for reading and
 *  writing all Exif headers in JPEG and TIFF images using PHP.
 *
 *  Copyright (C) 2004, 2005, 2006  Martin Geisler.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program in the file COPYING; if not, write to the
 *  Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 *  Boston, MA 02110-1301 USA
 */

/* $Id$ */


/**
 * Abstract class for numbers.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @version $Revision$
 * @date $Date$
 * @license http://www.gnu.org/licenses/gpl.html GNU General Public
 * License (GPL)
 * @package PEL
 */

/**#@+ Required class definitions. */
require_once('PelException.php');
require_once('PelEntry.php');
/**#@-*/


/**
 * Exception cast when numbers overflow.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @package PEL
 * @subpackage Exception
 */
class PelOverflowException extends PelException {

    /**
     * Construct a new overflow exception.
     *
     * @param int the value that is out of range.
     *
     * @param int the minimum allowed value.
     *
     * @param int the maximum allowed value.
     */
    function __construct($v, $min, $max) {
        parent::__construct('Value %.0f out of range [%.0f, %.0f]',
        $v, $min, $max);
    }
}


/**
 * Class for holding numbers.
 *
 * This class can hold numbers, with range checks.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @package PEL
 */
abstract class PelEntryNumber extends PelEntry {

    /**
     * The value held by this entry.
     *
     * @var array
     */
    protected $value = array();

    /**
     * The minimum allowed value.
     *
     * Any attempt to change the value below this variable will result
     * in a {@link PelOverflowException} being thrown.
     *
     * @var int
     */
    protected $min;

    /**
     * The maximum allowed value.
     *
     * Any attempt to change the value over this variable will result in
     * a {@link PelOverflowException} being thrown.
     *
     * @var int
     */
    protected $max;

    /**
     * The dimension of the number held.
     *
     * Normal numbers have a dimension of one, pairs have a dimension of
     * two, etc.
     *
     * @var int
     */
    protected $dimension = 1;


    /**
     * Change the value.
     *
     * This method can change both the number of components and the
     * value of the components.  Range checks will be made on the new
     * value, and a {@link PelOverflowException} will be thrown if the
     * value is found to be outside the legal range.
     *
     * The method accept several number arguments.  The {@link getValue}
     * method will always return an array except for when a single
     * number is given here.
     *
     * @param int|array $value... the new value(s).  This can be zero or
     * more numbers, that is, either integers or arrays.  The input will
     * be checked to ensure that the numbers are within the valid range.
     * If not, then a {@link PelOverflowException} will be thrown.
     *
     * @see getValue
     */
    function setValue(/* $value... */) {
        $value = func_get_args();
        $this->setValueArray($value);
    }


    /**
     * Change the value.
     *
     * This method can change both the number of components and the
     * value of the components.  Range checks will be made on the new
     * value, and a {@link PelOverflowException} will be thrown if the
     * value is found to be outside the legal range.
     *
     * @param array the new values.  The array must contain the new
     * numbers.
     *
     * @see getValue
     */
    function setValueArray($value) {
        foreach ($value as $v)
        $this->validateNumber($v);

        $this->components = count($value);
        $this->value      = $value;
    }


    /**
     * Return the numeric value held.
     *
     * @return int|array this will either be a single number if there is
     * only one component, or an array of numbers otherwise.
     */
    function getValue() {
        if ($this->components == 1)
        return $this->value[0];
        else
        return $this->value;
    }


    /**
     * Validate a number.
     *
     * This method will check that the number given is within the range
     * given my {@link getMin()} and {@link getMax()}, inclusive.  If
     * not, then a {@link PelOverflowException} is thrown.
     *
     * @param int|array the number in question.
     *
     * @return void nothing, but will throw a {@link
     * PelOverflowException} if the number is found to be outside the
     * legal range and {@link Pel::$strict} is true.
     */
    function validateNumber($n) {
        if ($this->dimension == 1) {
            if ($n < $this->min || $n > $this->max)
            Pel::maybeThrow(new PelOverflowException($n,
            $this->min,
            $this->max));
        } else {
            for ($i = 0; $i < $this->dimension; $i++)
            if ($n[$i] < $this->min || $n[$i] > $this->max)
            Pel::maybeThrow(new PelOverflowException($n[$i],
            $this->min,
            $this->max));
        }
    }


    /**
     * Add a number.
     *
     * This appends a number to the numbers already held by this entry,
     * thereby increasing the number of components by one.
     *
     * @param int|array the number to be added.
     */
    function addNumber($n) {
        $this->validateNumber($n);
        $this->value[] = $n;
        $this->components++;
    }


    /**
     * Convert a number into bytes.
     *
     * The concrete subclasses will have to implement this method so
     * that the numbers represented can be turned into bytes.
     *
     * The method will be called once for each number held by the entry.
     *
     * @param int the number that should be converted.
     *
     * @param PelByteOrder one of {@link PelConvert::LITTLE_ENDIAN} and
     * {@link PelConvert::BIG_ENDIAN}, specifying the target byte order.
     *
     * @return string bytes representing the number given.
     */
    abstract function numberToBytes($number, $order);


    /**
     * Turn this entry into bytes.
     *
     * @param PelByteOrder the desired byte order, which must be either
     * {@link PelConvert::LITTLE_ENDIAN} or {@link
     * PelConvert::BIG_ENDIAN}.
     *
     * @return string bytes representing this entry.
     */
    function getBytes($o) {
        $bytes = '';
        for ($i = 0; $i < $this->components; $i++) {
            if ($this->dimension == 1) {
                $bytes .= $this->numberToBytes($this->value[$i], $o);
            } else {
                for ($j = 0; $j < $this->dimension; $j++) {
                    $bytes .= $this->numberToBytes($this->value[$i][$j], $o);
                }
            }
        }
        return $bytes;
    }


    /**
     * Format a number.
     *
     * This method is called by {@link getText} to format numbers.
     * Subclasses should override this method if they need more
     * sophisticated behavior than the default, which is to just return
     * the number as is.
     *
     * @param int the number which will be formatted.
     *
     * @param boolean it could be that there is both a verbose and a
     * brief formatting available, and this argument controls that.
     *
     * @return string the number formatted as a string suitable for
     * display.
     */
    function formatNumber($number, $brief = false) {
        return $number;
    }


    /**
     * Get the numeric value of this entry as text.
     *
     * @param boolean use brief output?  The numbers will be separated
     * by a single space if brief output is requested, otherwise a space
     * and a comma will be used.
     *
     * @return string the numbers(s) held by this entry.
     */
    function getText($brief = false) {
        if ($this->components == 0)
        return '';

        $str = $this->formatNumber($this->value[0]);
        for ($i = 1; $i < $this->components; $i++) {
            $str .= ($brief ? ' ' : ', ');
            $str .= $this->formatNumber($this->value[$i]);
        }

        return $str;
    }

}

