<?php
/**
 * Base renderer for rendering HTML based diffs for PHP DiffLib.
 *
 * PHP version 5
 *
 * Copyright (c) 2009 Chris Boulton <chris.boulton@interspire.com>
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 *  - Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *  - Neither the name of the Chris Boulton nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * @package DiffLib
 * @author Chris Boulton <chris.boulton@interspire.com>
 * @copyright (c) 2009 Chris Boulton
 * @license New BSD License http://www.opensource.org/licenses/bsd-license.php
 * @version 1.1
 * @link http://github.com/chrisboulton/php-diff
 */
require_once dirname ( __FILE__ ) . '/../Abstract.php';
class Diff_Renderer_Html_Array extends Diff_Renderer_Abstract {
	/**
	 *
	 * @var array Array of the default options that apply to this renderer.
	 */
	protected $defaultOptions = array (
			'tabSize' => 4 
	);
	
	/**
	 * Render and return an array structure suitable for generating HTML
	 * based differences.
	 * Generally called by subclasses that generate a
	 * HTML based diff and return an array of the changes to show in the diff.
	 *
	 * @return array An array of the generated chances, suitable for presentation in HTML.
	 */
	public function render() {
		// As we'll be modifying a & b to include our change markers,
		// we need to get the contents and store them here. That way
		// we're not going to destroy the original data
		$a = $this->diff->getA ();
		$b = $this->diff->getB ();
		
		$changes = array ();
		$opCodes = $this->diff->getGroupedOpcodes ();
		foreach ( $opCodes as $group ) {
			$blocks = array ();
			$lastTag = null;
			$lastBlock = 0;
			foreach ( $group as $code ) {
				list ( $tag, $i1, $i2, $j1, $j2 ) = $code;
				
				if ($tag == 'replace' && $i2 - $i1 == $j2 - $j1) {
					for($i = 0; $i < ($i2 - $i1); ++ $i) {
						$fromLine = $a [$i1 + $i];
						$toLine = $b [$j1 + $i];
						
						list ( $start, $end ) = $this->getChangeExtent ( $fromLine, $toLine );
						if ($start != 0 || $end != 0) {
							$last = $end + strlen ( $fromLine );
							$fromLine = substr_replace ( $fromLine, "\0", $start, 0 );
							$fromLine = substr_replace ( $fromLine, "\1", $last + 1, 0 );
							$last = $end + strlen ( $toLine );
							$toLine = substr_replace ( $toLine, "\0", $start, 0 );
							$toLine = substr_replace ( $toLine, "\1", $last + 1, 0 );
							$a [$i1 + $i] = $fromLine;
							$b [$j1 + $i] = $toLine;
						}
					}
				}
				
				if ($tag != $lastTag) {
					$blocks [] = array (
							'tag' => $tag,
							'base' => array (
									'offset' => $i1,
									'lines' => array () 
							),
							'changed' => array (
									'offset' => $j1,
									'lines' => array () 
							) 
					);
					$lastBlock = count ( $blocks ) - 1;
				}
				
				$lastTag = $tag;
				
				if ($tag == 'equal') {
					$lines = array_slice ( $a, $i1, ($i2 - $i1) );
					$blocks [$lastBlock] ['base'] ['lines'] += $this->formatLines ( $lines );
					$lines = array_slice ( $b, $j1, ($j2 - $j1) );
					$blocks [$lastBlock] ['changed'] ['lines'] += $this->formatLines ( $lines );
				} else {
					if ($tag == 'replace' || $tag == 'delete') {
						$lines = array_slice ( $a, $i1, ($i2 - $i1) );
						$lines = $this->formatLines ( $lines );
						$lines = str_replace ( array (
								"\0",
								"\1" 
						), array (
								'<del>',
								'</del>' 
						), $lines );
						$blocks [$lastBlock] ['base'] ['lines'] += $lines;
					}
					
					if ($tag == 'replace' || $tag == 'insert') {
						$lines = array_slice ( $b, $j1, ($j2 - $j1) );
						$lines = $this->formatLines ( $lines );
						$lines = str_replace ( array (
								"\0",
								"\1" 
						), array (
								'<ins>',
								'</ins>' 
						), $lines );
						$blocks [$lastBlock] ['changed'] ['lines'] += $lines;
					}
				}
			}
			$changes [] = $blocks;
		}
		return $changes;
	}
	
	/**
	 * Given two strings, determine where the changes in the two strings
	 * begin, and where the changes in the two strings end.
	 *
	 * @param string $fromLine
	 *        	The first string.
	 * @param string $toLine
	 *        	The second string.
	 * @return array Array containing the starting position (0 by default) and the ending position (-1 by default)
	 */
	private function getChangeExtent($fromLine, $toLine) {
		$start = 0;
		$limit = min ( strlen ( $fromLine ), strlen ( $toLine ) );
		while ( $start < $limit && $fromLine {$start} == $toLine {$start} ) {
			++ $start;
		}
		$end = - 1;
		$limit = $limit - $start;
		while ( - $end <= $limit && substr ( $fromLine, $end, 1 ) == substr ( $toLine, $end, 1 ) ) {
			-- $end;
		}
		return array (
				$start,
				$end + 1 
		);
	}
	
	/**
	 * Format a series of lines suitable for output in a HTML rendered diff.
	 * This involves replacing tab characters with spaces, making the HTML safe
	 * for output, ensuring that double spaces are replaced with &nbsp; etc.
	 *
	 * @param array $lines
	 *        	Array of lines to format.
	 * @return array Array of the formatted lines.
	 */
	private function formatLines($lines) {
		$lines = array_map ( array (
				$this,
				'ExpandTabs' 
		), $lines );
		$lines = array_map ( array (
				$this,
				'HtmlSafe' 
		), $lines );
		foreach ( $lines as &$line ) {
			$line = preg_replace_callback ( '# ( +)|^ #', __CLASS__ . "::fixSpaces", $line );
		}
		return $lines;
	}
	
	/**
	 * Replace a string containing spaces with a HTML representation using &nbsp;.
	 *
	 * @param string $matches
	 *        	Regex matches array.
	 * @return string The HTML representation of the string.
	 */
	public static function fixSpaces($matches) {
		$spaces = isset ( $matches [1] ) ? $matches [1] : '';
		$count = strlen ( $spaces );
		if ($count == 0) {
			return '';
		}
		
		$div = floor ( $count / 2 );
		$mod = $count % 2;
		return str_repeat ( '&nbsp; ', $div ) . str_repeat ( '&nbsp;', $mod );
	}
	
	/**
	 * Replace tabs in a single line with a number of spaces as defined by the tabSize option.
	 *
	 * @param string $line
	 *        	The containing tabs to convert.
	 * @return string The line with the tabs converted to spaces.
	 */
	private function expandTabs($line) {
		return str_replace ( "\t", str_repeat ( ' ', $this->options ['tabSize'] ), $line );
	}
	
	/**
	 * Make a string containing HTML safe for output on a page.
	 *
	 * @param string $string
	 *        	The string.
	 * @return string The string with the HTML characters replaced by entities.
	 */
	private function htmlSafe($string) {
		return htmlspecialchars ( $string, ENT_NOQUOTES, 'UTF-8' );
	}
}