<?php
/**
 *--------------------------------------------------------------------
 *
 * Sub-Class - ISBN-10 and ISBN-13
 *
 * You can provide an ISBN with 10 digits with or without the checksum.
 * You can provide an ISBN with 13 digits with or without the checksum.
 * Calculate the ISBN based on the EAN-13 encoding.
 *
 * The checksum is always displayed.
 *
 *--------------------------------------------------------------------
 * Copyright (C) Jean-Sebastien Goupil
 * http://www.barcodephp.com
 */
include_once('BCGean13.barcode.php');

class BCGisbn extends BCGean13 {
	const GS1_AUTO = 0;
	const GS1_PREFIX978 = 1;
	const GS1_PREFIX979 = 2;

	private $gs1;

	/**
	 * Constructor.
	 *
	 * @param int $gs1
	 */
	public function __construct($gs1 = self::GS1_AUTO) {
		parent::__construct();
		$this->setGS1($gs1);
	}

	/**
	 * Adds the default label.
	 */
	protected function addDefaultLabel() {
		if ($this->isDefaultEanLabelEnabled()) {
			$isbn = $this->createISBNText();
			$font = $this->font;

			$topLabel = new BCGLabel($isbn, $font, BCGLabel::POSITION_TOP, BCGLabel::ALIGN_CENTER);

			$this->addLabel($topLabel);
		}

		parent::addDefaultLabel();
	}

	/**
	 * Sets the first numbers of the barcode.
	 *  - GS1_AUTO: Adds 978 before the code
	 *  - GS1_PREFIX978: Adds 978 before the code
	 *  - GS1_PREFIX979: Adds 979 before the code
	 *
	 * @param int $gs1
	 */
	public function setGS1($gs1) {
		$gs1 = (int)$gs1;
		if ($gs1 !== self::GS1_AUTO && $gs1 !== self::GS1_PREFIX978 && $gs1 !== self::GS1_PREFIX979) {
			throw new BCGArgumentException('The GS1 argument must be BCGisbn::GS1_AUTO, BCGisbn::GS1_PREFIX978, or BCGisbn::GS1_PREFIX979', 'gs1');
		}

		$this->gs1 = $gs1;
	}

	/**
	 * Check chars allowed.
	 */
	protected function checkCharsAllowed() {
		$c = strlen($this->text);

		// Special case, if we have 10 digits, the last one can be X
		if ($c === 10) {
			if (array_search($this->text[9], $this->keys) === false && $this->text[9] !== 'X') {
				throw new BCGParseException('isbn', 'The character \'' . $this->text[9] . '\' is not allowed.');
			}

			// Drop the last char
			$this->text = substr($this->text, 0, 9);
		}

		return parent::checkCharsAllowed();
	}

	/**
	 * Check correct length.
	 */
	protected function checkCorrectLength() {
		$c = strlen($this->text);

		// If we have 13 chars just flush the last one
		if ($c === 13) {
			$this->text = substr($this->text, 0, 12);
		} elseif ($c === 9 || $c === 10) {
			if ($c === 10) {
				// Before dropping it, we check if it's legal
				if (array_search($this->text[9], $this->keys) === false && $this->text[9] !== 'X') {
					throw new BCGParseException('isbn', 'The character \'' . $this->text[9] . '\' is not allowed.');
				}

				$this->text = substr($this->text, 0, 9);
			}

			if ($this->gs1 === self::GS1_AUTO || $this->gs1 === self::GS1_PREFIX978) {
				$this->text = '978' . $this->text;
			} elseif ($this->gs1 === self::GS1_PREFIX979) {
				$this->text = '979' . $this->text;
			}
		} elseif ($c !== 12) {
			throw new BCGParseException('isbn', 'The code parsed must be 9, 10, 12, or 13 digits long.');
		}
	}

	/**
	 * Creates the ISBN text.
	 *
	 * @return string
	 */
	private function createISBNText() {
		$isbn = '';
		if (!empty($this->text)) { 
			// We try to create the ISBN Text... the hyphen really depends the ISBN agency.
			// We just put one before the checksum and one after the GS1 if present.
			$c = strlen($this->text);
			if ($c === 12 || $c === 13) {
				// If we have 13 characters now, just transform it temporarily to find the checksum...
				// Further in the code we take care of that anyway.
				$lastCharacter = '';
				if ($c === 13) {
					$lastCharacter = $this->text[12];
					$this->text = substr($this->text, 0, 12);
				}
				
				$checksum = $this->processChecksum();
				$isbn = 'ISBN ' . substr($this->text, 0, 3) . '-' . substr($this->text, 3, 9) . '-' . $checksum;
				
				// Put the last character back
				if ($c === 13) {
					$this->text .= $lastCharacter;
				}
			} elseif ($c === 9 || $c === 10) {
				$checksum = 0;
				for ($i = 10; $i >= 2; $i--) {
					$checksum += $this->text[10 - $i] * $i;
				}

				$checksum = 11 - $checksum % 11;
				if ($checksum === 10) {
					$checksum = 'X';
				}

				$isbn = 'ISBN ' . substr($this->text, 0, 9) . '-' . $checksum;
			}
		}

		return $isbn;
	}
}
?>