<?php
/**
 * Compress CSS
 *
 * This is a heavy regex-based removal of whitespace, unnecessary
 * comments and tokens, and some CSS value minimization, where practical.
 * Many steps have been taken to avoid breaking comment-based hacks,
 * including the ie5/mac filter (and its inversion), but expect tricky
 * hacks involving comment tokens in 'content' value strings to break
 * minimization badly. A test suite is available.
 *
 * @package Minify
 * @author  Stephen Clay <steve@mrclay.org>
 * @author  http://code.google.com/u/1stvamp/ (Issue 64 patch)
 */
class Minify_CSS_Compressor {

	/**
	 * Minify a CSS string
	 *
	 * @param string $css
	 *
	 * @param array  $options (currently ignored)
	 *
	 * @return string
	 */
	public static function process( $css, $options = array() ) {
		$obj = new Minify_CSS_Compressor( $options );
		return $obj->_process( $css );
	}

	/**
	 * @var array
	 */
	protected $_options = null;

	/**
	 * Are we "in" a hack? I.e. are some browsers targetted until the next comment?
	 *
	 * @var bool
	 */
	protected $_inHack = false;


	/**
	 * Constructor
	 *
	 * @param array $options (currently ignored)
	 */
	private function __construct( $options ) {
		$this->_options = $options;
	}

	/**
	 * Minify a CSS string
	 *
	 * @param string $css
	 *
	 * @return string
	 */
	protected function _process( $css ) {
		$css = str_replace( "\r\n", "\n", $css );

		// preserve empty comment after '>'
		// http://www.webdevout.net/css-hacks#in_css-selectors
		$css = preg_replace( '@>/\\*\\s*\\*/@', '>/*keep*/', $css );

		// preserve empty comment between property and value
		// http://css-discuss.incutio.com/?page=BoxModelHack
		$css = preg_replace( '@/\\*\\s*\\*/\\s*:@', '/*keep*/:', $css );
		$css = preg_replace( '@:\\s*/\\*\\s*\\*/@', ':/*keep*/', $css );

		// apply callback to all valid comments (and strip out surrounding ws
		$css = preg_replace_callback( '@\\s*/\\*([\\s\\S]*?)\\*/\\s*@'
			, array( $this, '_commentCB' ), $css );

		// remove ws around { } and last semicolon in declaration block
		$css = preg_replace( '/\\s*{\\s*/', '{', $css );
		$css = preg_replace( '/;?\\s*}\\s*/', '}', $css );

		// remove ws surrounding semicolons
		$css = preg_replace( '/\\s*;\\s*/', ';', $css );

		// remove ws around urls
		$css = preg_replace( '/
                url\\(      # url(
                \\s*
                ([^\\)]+?)  # 1 = the URL (really just a bunch of non right parenthesis)
                \\s*
                \\)         # )
            /x', 'url($1)', $css );

		// remove ws between rules and colons
		$css = preg_replace( '/
                \\s*
                ([{;])              # 1 = beginning of block or rule separator 
                \\s*
                ([\\*_]?[\\w\\-]+)  # 2 = property (and maybe IE filter)
                \\s*
                :
                \\s*
                (\\b|[#\'"-])        # 3 = first character of a value
            /x', '$1$2:$3', $css );

		// remove ws in selectors
		$css = preg_replace_callback( '/
                (?:              # non-capture
                    \\s*
                    [^~>+,\\s]+  # selector part
                    \\s*
                    [,>+~]       # combinators
                )+
                \\s*
                [^~>+,\\s]+      # selector part
                {                # open declaration block
            /x'
			, array( $this, '_selectorsCB' ), $css );

		// minimize hex colors
		$css = preg_replace( '/([^=])#([a-f\\d])\\2([a-f\\d])\\3([a-f\\d])\\4([\\s;\\}])/i'
			, '$1#$2$3$4$5', $css );

		// remove spaces between font families
		$css = preg_replace_callback( '/font-family:([^;}]+)([;}])/'
			, array( $this, '_fontFamilyCB' ), $css );

		$css = preg_replace( '/@import\\s+url/', '@import url', $css );

		// replace any ws involving newlines with a single newline
		$css = preg_replace( '/[ \\t]*\\n+\\s*/', "\n", $css );

		// separate common descendent selectors w/ newlines (to limit line lengths)
		$css = preg_replace( '/([\\w#\\.\\*]+)\\s+([\\w#\\.\\*]+){/', "$1\n$2{", $css );

		// Use newline after 1st numeric value (to limit line lengths).
		$css = preg_replace( '/
            ((?:padding|margin|border|outline):\\d+(?:px|em)?) # 1 = prop : 1st numeric value
            \\s+
            /x'
			, "$1\n", $css );

		// prevent triggering IE6 bug: http://www.crankygeek.com/ie6pebug/
		$css = preg_replace( '/:first-l(etter|ine)\\{/', ':first-l$1 {', $css );

		return trim( $css );
	}

	/**
	 * Replace what looks like a set of selectors
	 *
	 * @param array $m regex matches
	 *
	 * @return string
	 */
	protected function _selectorsCB( $m ) {
		// remove ws around the combinators
		return preg_replace( '/\\s*([,>+~])\\s*/', '$1', $m[0] );
	}

	/**
	 * Process a comment and return a replacement
	 *
	 * @param array $m regex matches
	 *
	 * @return string
	 */
	protected function _commentCB( $m ) {
		$hasSurroundingWs = ( trim( $m[0] ) !== $m[1] );
		$m = $m[1];
		// $m is the comment content w/o the surrounding tokens,
		// but the return value will replace the entire comment.
		if ( $m === 'keep' ) {
			return '/**/';
		}
		if ( $m === '" "' ) {
			// component of http://tantek.com/CSS/Examples/midpass.html
			return '/*" "*/';
		}
		if ( preg_match( '@";\\}\\s*\\}/\\*\\s+@', $m ) ) {
			// component of http://tantek.com/CSS/Examples/midpass.html
			return '/*";}}/* */';
		}
		if ( $this->_inHack ) {
			// inversion: feeding only to one browser
			if ( preg_match( '@
                    ^/               # comment started like /*/
                    \\s*
                    (\\S[\\s\\S]+?)  # has at least some non-ws content
                    \\s*
                    /\\*             # ends like /*/ or /**/
                @x', $m, $n )
			) {
				// end hack mode after this comment, but preserve the hack and comment content
				$this->_inHack = false;
				return "/*/{$n[1]}/**/";
			}
		}
		if ( substr( $m, -1 ) === '\\' ) { // comment ends like \*/
			// begin hack mode and preserve hack
			$this->_inHack = true;
			return '/*\\*/';
		}
		if ( $m !== '' && $m[0] === '/' ) { // comment looks like /*/ foo */
			// begin hack mode and preserve hack
			$this->_inHack = true;
			return '/*/*/';
		}
		if ( $this->_inHack ) {
			// a regular comment ends hack mode but should be preserved
			$this->_inHack = false;
			return '/**/';
		}
		// Issue 107: if there's any surrounding whitespace, it may be important, so
		// replace the comment with a single space
		return $hasSurroundingWs // remove all other comments
			? ' '
			: '';
	}

	/**
	 * Process a font-family listing and return a replacement
	 *
	 * @param array $m regex matches
	 *
	 * @return string
	 */
	protected function _fontFamilyCB( $m ) {
		// Issue 210: must not eliminate WS between words in unquoted families
		$pieces = preg_split( '/(\'[^\']+\'|"[^"]+")/', $m[1], null, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );
		$out = 'font-family:';
		while ( null !== ( $piece = array_shift( $pieces ) ) ) {
			if ( $piece[0] !== '"' && $piece[0] !== "'" ) {
				$piece = preg_replace( '/\\s+/', ' ', $piece );
				$piece = preg_replace( '/\\s?,\\s?/', ',', $piece );
			}
			$out .= $piece;
		}
		return $out . $m[2];
	}
}

?>