<?php
	#
	#
	# A PHP auto-linking library
	#
	# $Id: lib_autolink.php,v 1.4 2006/12/09 20:36:50 cal Exp $
	#
	# http://appliedthinking.org/autolinking/
	#
	# By Cal Henderson <hide@address.com>
	# This code is licensed under a Creative Commons Attribution-ShareAlike 2.5 License
	# http://creativecommons.org/licenses/by-sa/2.5/
	#
	#

	####################################################################

	function autolink($text, $limit=30, $tagfill=''){

		$text = autolink_do($text, 'https://',	$limit, $tagfill);
		$text = autolink_do($text, 'http://',	$limit, $tagfill);
		$text = autolink_do($text, 'ftp://',	$limit, $tagfill);
		$text = autolink_do($text, 'www.',	$limit, $tagfill);
		return $text;
	}

	####################################################################

	function autolink_do($text, $sub, $limit, $tagfill){

		$sub_len = strlen($sub);

		$text_l = StrToLower($text);
		$cursor = 0;
		$loop = 1;
		$buffer = '';

		while (($cursor < strlen($text)) && $loop){

			$ok = 1;
			$pos = strpos($text_l, $sub, $cursor);

			if ($pos === false){

				$loop = 0;
				$ok = 0;

			}else{

				$pre_hit = substr($text, $cursor, $pos-$cursor);
				$hit = substr($text, $pos, $sub_len);
				$pre = substr($text, 0, $pos);
				$post = substr($text, $pos + $sub_len);

				$fail_text = $pre_hit.$hit;
				$fail_len = strlen($fail_text);

				#
				# substring found - first check to see if we're inside a link tag already...
				#

				$bits = preg_split("!</a>!i", $pre);
				$last_bit = array_pop($bits);
				if (preg_match("!<a\s!i", $last_bit)){

					#echo "fail 1 at $cursor<br />\n";

					$ok = 0;
					$cursor += $fail_len;
					$buffer .= $fail_text;
				}
			}

			#
			# looks like a nice spot to autolink from - check the pre
			# to see if there was whitespace before this match
			#

			if ($ok){

				if ($pre){
					if (!preg_match('![\s\(\[\{]$!s', $pre)){

						#echo "fail 2 at $cursor ($pre)<br />\n";

						$ok = 0;
						$cursor += $fail_len;
						$buffer .= $fail_text;
					}
				}
			}

			#
			# we want to autolink here - find the extent of the url
			#

			if ($ok){
				if (preg_match('/^([a-z0-9\-\.\/\-_%~!?=,:;&+*#@\(\)\$]+)/i', $post, $matches)){

					$url = $hit.$matches[1];

					#
					# remove trailing punctuation from url
					#

					if (preg_match('|[.,!;:?]$|', $url)){
						$url = substr($url, 0, strlen($url)-1);
					}
					foreach (array('()', '[]', '{}') as $pair){
						$o = substr($pair, 0, 1);
						$c = substr($pair, 1, 1);
						if (preg_match("!^(\\$c|^)[^\\$o]+\\$c$!", $url)){
							$url = substr($url, 0, strlen($url)-1);
						}
					}

					#
					# commit
					#

					$cursor += strlen($url) + strlen($pre_hit);
					$buffer .= $pre_hit;

					#
					# nice-i-fy url here
					#

					$link_url = $url;
					$display_url = $url;

					if (preg_match('!^([a-z]+)://!i', $url, $m)){
						$display_url = substr($display_url, strlen($m[1])+3);
					}else{
						$link_url = "http://$link_url";
					}

					$display_url = autolink_label($display_url, $limit);

					#
					# add the url
					#

					$buffer .= "<a href=\"$link_url\"$tagfill>$display_url</a>";
				
				}else{
					#echo "fail 3 at $cursor<br />\n";

					$ok = 0;
					$cursor += $fail_len;
					$buffer .= $fail_text;
				}
			}

		}

		#
		# add everything from the cursor to the end onto the buffer.
		#

		$buffer .= substr($text, $cursor);

		return $buffer;
	}

	####################################################################

	function autolink_label($text, $limit){

		if (!$limit){ return $text; }

		if (strlen($text) > $limit){
			return substr($text, 0, $limit-3).'...';
		}

		return $text;
	}

	####################################################################

	function autolink_email($text, $tagfill=''){

		$atom = '[^()<>@,;:\\\\".\\[\\]\\x00-\\x20\\x7f]+'; # from RFC822

		#die($atom);

		$text_l = StrToLower($text);
		$cursor = 0;
		$loop = 1;
		$buffer = '';

		while(($cursor < strlen($text)) && $loop){

			#
			# find an '@' symbol
			#

			$ok = 1;
			$pos = strpos($text_l, '@', $cursor);

			if ($pos === false){

				$loop = 0;
				$ok = 0;

			}else{

				$pre = substr($text, $cursor, $pos-$cursor);
				$hit = substr($text, $pos, 1);
				$post = substr($text, $pos + 1);

				$fail_text = $pre.$hit;
				$fail_len = strlen($fail_text);

				#die("$pre::$hit::$post::$fail_text");

				#
				# substring found - first check to see if we're inside a link tag already...
				#

				$bits = preg_split("!</a>!i", $pre);
				$last_bit = array_pop($bits);
				if (preg_match("!<a\s!i", $last_bit)){

					#echo "fail 1 at $cursor<br />\n";

					$ok = 0;
					$cursor += $fail_len;
					$buffer .= $fail_text;
				}
			}

			#
			# check backwards
			#

			if ($ok){
				if (preg_match("!($atom(\.$atom)*)\$!", $pre, $matches)){

					# move matched part of address into $hit

					$len = strlen($matches[1]);
					$plen = strlen($pre);

					$hit = substr($pre, $plen-$len).$hit;
					$pre = substr($pre, 0, $plen-$len);

				}else{

					#echo "fail 2 at $cursor ($pre)<br />\n";

					$ok = 0;
					$cursor += $fail_len;
					$buffer .= $fail_text;
				}
			}

			#
			# check forwards
			#

			if ($ok){
				if (preg_match("!^($atom(\.$atom)*)!", $post, $matches)){

					# move matched part of address into $hit

					$len = strlen($matches[1]);

					$hit .= substr($post, 0, $len);
					$post = substr($post, $len);

				}else{
					#echo "fail 3 at $cursor ($post)<br />\n";

					$ok = 0;
					$cursor += $fail_len;
					$buffer .= $fail_text;
				}
			}

			#
			# commit
			#

			if ($ok) {

				$cursor += strlen($pre) + strlen($hit);
				$buffer .= $pre;
				$buffer .= "<a href=\"mailto:$hit\"$tagfill>$hit</a>";

			}

		}

		#
		# add everything from the cursor to the end onto the buffer.
		#

		$buffer .= substr($text, $cursor);

		return $buffer;
	}

	####################################################################

?>