<?php
/*
	Ross Scrivener http://scrivna.com
	PHP file diff implementation
	
	Much credit goes to...
	
	Paul's Simple Diff Algorithm v 0.1
	(C) Paul Butler 2007 <http://www.paulbutler.org/>
	May be used and distributed under the zlib/libpng license.
	
	... for the actual diff code, i changed a few things and implemented a pretty interface to it.
*/
class filediff {

	var $changes = array();
	var $diff = array();
	var $linepadding = null;
	
	function doDiff($old, $new){
		if (!is_array($old)) $old = file($old);
		if (!is_array($new)) $new = file($new);
		
		foreach($old as $oindex => $ovalue){
			$nkeys = array_keys($new, $ovalue);
			foreach($nkeys as $nindex){
				$matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ? $matrix[$oindex - 1][$nindex - 1] + 1 : 1;
				if($matrix[$oindex][$nindex] > $maxlen){
					$maxlen = $matrix[$oindex][$nindex];
					$omax = $oindex + 1 - $maxlen;
					$nmax = $nindex + 1 - $maxlen;
				}
			}       
		}
		if($maxlen == 0) return array(array('d'=>$old, 'i'=>$new));
		
		return array_merge(
			$this->doDiff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
			array_slice($new, $nmax, $maxlen),
			$this->doDiff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
		
	}
	
	function diffWrap($old, $new){
		$this->diff = $this->doDiff($old, $new);
		$this->changes = array();
		$ndiff = array();
		foreach ($this->diff as $line => $k){
			if(is_array($k)){
				if (isset($k['d'][0]) || isset($k['i'][0])){
					$this->changes[] = $line;
					$ndiff[$line] = $k;
				}
			} else {
				$ndiff[$line] = $k;
			}
		}
		$this->diff = $ndiff;
		return $this->diff;
	}
	
	function formatcode($code){
		$code = htmlentities($code);
		$code = str_replace(" ",'&nbsp;',$code);
		$code = str_replace("\t",'&nbsp;&nbsp;&nbsp;&nbsp;',$code);
		return $code;
	}
	
	function showline($line){
		if ($this->linepadding === 0){
			if (in_array($line,$this->changes)) return true;
			return false;
		}
		if(is_null($this->linepadding)) return true;

		$start = (($line - $this->linepadding) > 0) ? ($line - $this->linepadding) : 0;
		$end = ($line + $this->linepadding);
		//echo '<br />'.$line.': '.$start.': '.$end;
		$search = range($start,$end);
		//pr($search);
		foreach($search as $k){
			if (in_array($k,$this->changes)) return true;
		}
		return false;

	}
	
	function inline($old, $new, $linepadding=null){
		$this->linepadding = $linepadding;
		
		$ret = '<pre><table width="100%" border="0" cellspacing="0" cellpadding="0" class="code">';
		$ret.= '<tr><td>Stock</td><td>Skin</td><td></td></tr>';
		$count_old = 1;
		$count_new = 1;
		
		$insert = false;
		$delete = false;
		$truncate = false;
		
		$diff = $this->diffWrap($old, $new);

		foreach($diff as $line => $k){
			if ($this->showline($line)){
				$truncate = false;
				if(is_array($k)){
					foreach ($k['d'] as $val){
						$class = '';
						if (!$delete){
							$delete = true;
							$class = 'first';
							if ($insert) $class = '';
							$insert = false;
						}
						$ret.= '<tr><th>'.$count_old.'</th>';
						$ret.= '<th>&nbsp;</th>';
						$ret.= '<td class="del '.$class.'">'.$this->formatcode($val).'</td>';
						$ret.= '</tr>';
						$count_old++;
					}
					foreach ($k['i'] as $val){
						$class = '';
						if (!$insert){
							$insert = true;
							$class = 'first';
							if ($delete) $class = '';
							$delete = false;
						}
						$ret.= '<tr><th>&nbsp;</th>';
						$ret.= '<th>'.$count_new.'</th>';
						$ret.= '<td class="ins '.$class.'">'.$this->formatcode($val).'</td>';
						$ret.= '</tr>';
						$count_new++;
					}
				} else {
					$class = ($delete) ? 'del_end' : '';
					$class = ($insert) ? 'ins_end' : $class;
					$delete = false;
					$insert = false;
					$ret.= '<tr><th>'.$count_old.'</th>';
					$ret.= '<th>'.$count_new.'</th>';
					$ret.= '<td class="'.$class.'">'.$this->formatcode($k).'</td>';
					$ret.= '</tr>';
					$count_old++;
					$count_new++;
				}
			} else {
				$class = ($delete) ? 'del_end' : '';
				$class = ($insert) ? 'ins_end' : $class;
				$delete = false;
				$insert = false;
				
				if (!$truncate){
					$truncate = true;
					$ret.= '<tr><th>...</th>';
					$ret.= '<th>...</th>';
					$ret.= '<td class="truncated '.$class.'">&nbsp;</td>';
					$ret.= '</tr>';
				}
				$count_old++;
				$count_new++;

			}
		}
		$ret.= '</table></pre>';
		return $ret;
	}
}