/src/Basset/Filter/UriRewriteFilter.php

<?php namespace Basset\Filter;

use Assetic\Asset\AssetInterface;
use Assetic\Filter\FilterInterface;

/**
 * UriRewriteFilter is a rewrite and port of the popular CssUriRewrite class written by Steve Clay.
 * Original source can be found by following the links below.
 * 
 * @author    Steve Clay
 * @link      <https://github.com/mrclay/minify>
 * @license   <https://github.com/mrclay/minify/blob/master/LICENSE.txt>
 * @package   Minify
 * @copyright 2008 Steve Clay / Ryan Grove
 */
class UriRewriteFilter implements FilterInterface {

	/**
	 * Applications document root. This is typically the public directory.
	 * 
	 * @var string
	 */
	protected $documentRoot;

	/**
	 * Root directory of the asset.
	 * 
	 * @var string
	 */
	protected $assetDirectory;

	/**
	 * Array of symbolic links.
	 * 
	 * @var array
	 */
	protected $symlinks;

	/**
	 * Create a new UriRewriteFilter instance.
	 * 
	 * @param  string  $documentRoot
	 * @param  array  $symlinks
	 * @return void
	 */
	public function __construct($documentRoot = null, $symlinks = array())
    {
    	$this->documentRoot = $this->realPath($documentRoot ?: $_SERVER['DOCUMENT_ROOT']);
    	$this->symlinks = $symlinks;
    }

    /**
     * Apply filter on file load.
     * 
     * @param  Assetic\Asset\AssetInterface  $asset
     * @return void
     */
	public function filterLoad(AssetInterface $asset){}

	/**
	 * Apply a filter on file dump.
	 * 
	 * @param  Assetic\Asset\AssetInterface  $asset
	 * @return void
	 */
	public function filterDump(AssetInterface $asset)
	{
		$this->assetDirectory = $this->realPath($asset->getSourceRoot());
		
		$content = $asset->getContent();

		// Spin through the symlinks and normalize them.
		foreach ($this->symlinks as $link => $target)
		{
			if ($link == '//')
			{
				$link = $this->documentRoot;
			}
			else
			{
				$link = str_replace('//', $this->documentRoot.'/', $link);
			}

			$link = strtr($link, '/', DIRECTORY_SEPARATOR);

			$this->symlinks[$link] = $this->realPath($target);
		}

		$content = $this->trimUrls($content);

		$content = preg_replace_callback('/@import\\s+([\'"])(.*?)[\'"]/', array($this, 'processUriCallback'), $content);
		$content = preg_replace_callback('/url\\(\\s*([^\\)\\s]+)\\s*\\)/', array($this, 'processUriCallback'), $content);

		$asset->setContent($content);
	}

	/**
	 * Takes a path and transforms it to a real path.
	 * 
	 * @param  string  $path
	 * @return string
	 */
    protected function realPath($path)
    {
    	if ($realPath = realpath($path))
    	{
    		$path = $realPath;
    	}

    	return rtrim($path, '/\\');
    }

    /**
     * Trims URLs.
     * 
     * @param  string  $content
     * @return string
     */
	protected function trimUrls($content)
	{
		return preg_replace('/url\\(\\s*([^\\)]+?)\\s*\\)/x', 'url($1)', $content);
	}

	/**
	 * Processes a regular expression callback, determines the URI and returns the rewritten URIs.
	 * 
	 * @param  array  $matches
	 * @return string
	 */
	protected function processUriCallback($matches)
	{
		$isImport = $matches[0][0] === '@';

		// Determine what the quote character and the URI is, if there is one.
		$quoteCharacter = $uri = null;

		if ($isImport)
		{
			$quoteCharater = $matches[1];

			$uri = $matches[2];
		}
		else
		{
			if ($matches[1][0] === "'" or $matches[1][0] === '"')
			{
				$quoteCharacter = $matches[1][0];
			}

			if ( ! $quoteCharacter)
			{
				$uri = $matches[1];
			}
			else
			{
				$uri = substr($matches[1], 1, strlen($matches[1]) - 2);
			}
		}

		// Analyze the URI
		if ($uri[0] !== '/' and strpos($uri, '//') === false and strpos($uri, 'data') !== 0)
		{
			$uri = $this->rewriteRelative($uri);
		}

		if ($isImport)
		{
			return "@import {$quoteCharacter}{$uri}{$quoteCharacter}";
		}

		return "url({$quoteCharacter}{$uri}{$quoteCharacter})";
	}

	/**
	 * Rewrites a relative URI.
	 * 
	 * @param  string  $uri
	 * @return string
	 */
	protected function rewriteRelative($uri)
	{
		$path = strtr($this->assetDirectory, '/', DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR.strtr($uri, '/', DIRECTORY_SEPARATOR);

		foreach ($this->symlinks as $link => $target)
		{
			if (strpos($path, $target) === 0)
			{
				$path = $link.substr($path, strlen($target));

				break;
			}
		}

		// Strip the document root from the path.
		$path = substr($path, strlen($this->documentRoot));

		$uri = strtr($path, '/\\', '//');
		$uri = $this->removeDots($uri);

		return $uri;
	}

	/**
	 * Removes dots from a URI.
	 * 
	 * @param  string  $uri
	 * @return string
	 */
	protected function removeDots($uri)
	{
		$uri = str_replace('/./', '/', $uri);

		do
		{
			$uri = preg_replace('@/[^/]+/\\.\\./@', '/', $uri, 1, $changed);
		}
		while ($changed);

		return $uri;
	}

}