<?php
/*
WP-HTML-Compression 0.5 <http://www.svachon.com/blog/wp-html-compression/>
Reduce file size by shortening URLs and safely removing all standard comments and unnecessary white space from an HTML document.
*/
 
class WP_HTML_Compression
{
	// Settings
	protected $compress_css;
	protected $compress_js;
	protected $info_comment;
	protected $remove_comments;
	protected $shorten_urls;
 
	// Variables
	protected $html;
 
 
 
	public function __construct($html, $compress_css=true, $compress_js=false, $info_comment=true, $remove_comments=true, $shorten_urls=true)
	{
		if ($html !== '')
		{
			$this->compress_css = $compress_css;
			$this->compress_js = $compress_js;
			$this->info_comment = $info_comment;
			$this->remove_comments = $remove_comments;
			$this->shorten_urls = $shorten_urls;
 
			$this->parseHTML($html);
		}
	}
 
 
 
	public function __toString()
	{
		return $this->html;
	}
 
 
 
	protected function bottomComment($raw, $compressed)
	{
		$raw = strlen($raw);
		$compressed = strlen($compressed);
 
		$savings = ($raw-$compressed) / $raw * 100;
 
		$savings = round($savings, 2);
 
		return '<!--WP-HTML-Compression saved '.$savings.'%. Bytes before:'.$raw.', after:'.$compressed.'-->';
	}
 
 
 
	protected function callback_HTML_URLs($matches)
	{
		// [2] is an attribute value that is encapsulated with "" and [3] with ''
		return $matches[1].'="'.absolute_to_relative_url($matches[2].$matches[3]).'"';
	}
 
 
 
	protected function minifyHTML($html)
	{
		$pattern = '/<(?<script>script).*?<\/script\s*>|<(?<style>style).*?<\/style\s*>|<!(?<comment>--).*?-->|<(?<tag>[\/\w.:-]*)(?:".*?"|\'.*?\'|[^\'">]+)*>|(?<text>((<[^!\/\w.:-])?[^<]*)+)|/si';
 
		preg_match_all($pattern, $html, $matches, PREG_SET_ORDER);
 
		$overriding = false;
		$raw_tag = false;
 
		// Variable reused for output
		$html = '';
 
		foreach ($matches as $token)
		{
			$tag = (isset($token['tag'])) ? strtolower($token['tag']) : null;
 
			$content = $token[0];
 
			if (is_null($tag))
			{
				if ( !empty($token['script']) )
				{
					$strip = $this->compress_js;
 
					// Will still end up shortening URLs within the script, but should be OK..
					// Gets Shortened:   test.href="http://domain.com/wp"+"-content";
					// Gets Bypassed:    test.href = "http://domain.com/wp"+"-content";
					$relate = true;
				}
				else if ( !empty($token['style']) )
				{
					$strip = $this->compress_css;
					$relate = true;
				}
				else if ($content == '<!--wp-html-compression no compression-->')
				{
					$overriding = !$overriding;
 
					// Don't print the comment
					continue;
				}
				else if ($this->remove_comments)
				{
					if (!$overriding && $raw_tag != 'textarea')
					{
						// Remove any HTML comments, except MSIE conditional comments
						$content = preg_replace('/<!--(?!\s*(?:\[if [^\]]+]|<!|>))(?:(?!-->).)*-->/s', '', $content);
					}
				}
			}
			else	// All tags except script, style and comments
			{
				if ($tag == 'pre' || $tag == 'textarea')
				{
					$raw_tag = $tag;
				}
				else if ($tag == '/pre' || $tag == '/textarea')
				{
					$raw_tag = false;
				}
				else if ($raw_tag || $overriding)
				{
					$strip = false;
				}
				else
				{
					if ($tag != '')
					{
						if (strpos($tag, '/') === false)
						{
							// Remove any empty attributes, except:
							// action, alt, content, src
							$content = preg_replace('/(\s+)(\w++(?<!action|alt|content|src)=(""|\'\'))/i', '$1', $content);
						}
 
						// Remove any space before the end of a tag (including closing tags and self-closing tags)
						$content = preg_replace('/\s+(\/?\>)/', '$1', $content);
 
						$relate = true;
					}
					else	// Content between opening and closing tags
					{
						// Avoid multiple spaces by checking previous character in output HTML
						if (strrpos($html,' ') === strlen($html)-1)
						{
							// Remove white space at the content beginning
							$content = preg_replace('/^[\s\r\n]+/', '', $content);
						}
					}
 
					$strip = true;
				}
			}
 
			// Relate URLs
			if ($relate && $this->shorten_urls)
			{
				$content = preg_replace_callback('/(action|href|src)=(?:"([^"]*)"|\'([^\']*)\')/i', array(&$this,'callback_HTML_URLs'), $content);
			}
 
			if ($strip)
			{
				$content = $this->removeWhiteSpace($content, $html);
			}
 
			$html .= $content;
		}
 
		return $html;
	}
 
 
 
	protected function parseHTML($html)
	{
		$this->html = $this->minifyHTML($html);
 
		if ($this->info_comment)
		{
			$this->html .= "\n" . $this->bottomComment($html, $this->html);
		}
	}
 
 
 
	protected function removeWhiteSpace($html, $full_html)
	{
		$html = str_replace("\t", ' ', $html);
		$html = str_replace("\r", ' ', $html);
		$html = str_replace("\n", ' ', $html);
 
		// This is over twice the speed of a RegExp
		while (strpos($html, '  ') !== false)
		{
			$html = str_replace('  ', ' ', $html);
		}
 
		return $html;
	}
}
 
 
 
function wp_html_compression_finish($html)
{
	// Plugin may be active, or another plugin may have already included this library
	if (!function_exists('absolute_to_relative_url'))
	{
		require_once dirname(__FILE__) . '/external/absolute-to-relative-urls.php';
	}
 
	return new WP_HTML_Compression($html);
}
 
 
 
function wp_html_compression_start()
{
	ob_start('wp_html_compression_finish');
}
 
 
wp_html_compression_start();
?>