<?php

	function findLinks($file)
	{
		if( is_file($file) && is_readable($file) )
		{	
			$links = array();
	
			// get whole file into a string
			if( $strfile = file_get_contents($file) )
			{
				while( $trim = stristr( $strfile, "href=" ) )
				{
					// strip "href=" from link
					$ltrim   = substr( $trim,  5   );
	
					// find out how links are enclosed
					switch( $ltrim[0] )
					{
						case '"':			// "http..."
							$delim = '"';
							$ltrim   = substr( $ltrim, 1 );
							break;
						case "'":
							$delim = "'";	// 'http...'
							$ltrim   = substr( $ltrim, 1 );
							break;
						default:
							$delim = ' ';	// http... (no enclosure)
					}
					
					// If no enclosure is found, not even a space, then use '>'
					$npos	 = strpos( $ltrim,  $delim );
					$opos    = strpos( $ltrim,  ">"    );
					if( $npos > $opos || $npos == false )
						$npos = $opos;
					
					// finish trimming using the position of the end delimiter
					$rtrim   = substr( $ltrim, 0, $npos );
					
					// add link to array
					$links[] = $rtrim;
					
					// update the string to be after this link
					$strfile = substr( $ltrim, $npos+1 );
				}
				return $links;
			}
		}
		return false;
	}
	function replaceLinks($file, $oldlinks, $newlinks)
	{
		if( is_file($file) && is_writeable($file) )
		{	
			// make sure we are supplied a newlink for every oldlink
			if ( count($oldlinks) == count($newlinks) )
			{
				// open file for reading and writing
				$fp = fopen($file, 'r+');
				
				if( $fp )
				{					
					// get whole file into a string
					if( $strfile = fread($fp, filesize($file) ) )
					{
						// replace links
						$strfile = str_replace( $oldlinks, $newlinks, $strfile );
						
						// pointer goes back to the beginning of file
						rewind($fp);
						
						// overwrite file with updated links
						$byteswritten = fwrite( $fp, $strfile, strlen($strfile) );
						
						fclose( $fp );
						
						return $byteswritten;
					}
				}
			}
		}
		return false;
	}
?>