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<?php

/**

 * Abstract minifier class.

 *

 * Please report bugs on https://github.com/matthiasmullie/minify/issues

 *

 * @author Matthias Mullie <minify@mullie.eu>

 * @copyright Copyright (c) 2012, Matthias Mullie. All rights reserved

 * @license MIT License

 */

namespace MatthiasMullie\Minify;

use MatthiasMullie\Minify\Exceptions\IOException;

use Psr\Cache\CacheItemInterface;

/**

 * Abstract minifier class.

 *

 * Please report bugs on https://github.com/matthiasmullie/minify/issues

 *

 * @author Matthias Mullie <minify@mullie.eu>

 * @copyright Copyright (c) 2012, Matthias Mullie. All rights reserved

 * @license MIT License

 */

abstract class Minify

{

    /**

     * The data to be minified.

     *

     * @var string[]

     */

    protected $data = array();

    /**

     * Array of patterns to match.

     *

     * @var string[]

     */

    protected $patterns = array();

    /**

     * This array will hold content of strings and regular expressions that have

     * been extracted from the JS source code, so we can reliably match "code",

     * without having to worry about potential "code-like" characters inside.

     *

     * @internal

     *

     * @var string[]

     */

    public $extracted = array();

    /**

     * Init the minify class - optionally, code may be passed along already.

     */

    public function __construct(/* $data = null, ... */)

    {

        // it's possible to add the source through the constructor as well ;)

        if (func_num_args()) {

            call_user_func_array(array($this, 'add'), func_get_args());

        }

    }

    /**

     * Add a file or straight-up code to be minified.

     *

     * @param string|string[] $data

     *

     * @return static

     */

    public function add($data /* $data = null, ... */)

    {

        // bogus "usage" of parameter $data: scrutinizer warns this variable is

        // not used (we're using func_get_args instead to support overloading),

        // but it still needs to be defined because it makes no sense to have

        // this function without argument :)

        $args = array($data) + func_get_args();

        // this method can be overloaded

        foreach ($args as $data) {

            if (is_array($data)) {

                call_user_func_array(array($this, 'add'), $data);

                continue;

            }

            // redefine var

            $data = (string) $data;

            // load data

            $value = $this->load($data);

            $key = ($data != $value) ? $data : count($this->data);

            // replace CR linefeeds etc.

            // @see https://github.com/matthiasmullie/minify/pull/139

            $value = str_replace(array("\r\n", "\r"), "\n", $value);

            // store data

            $this->data[$key] = $value;

        }

        return $this;

    }

    /**

     * Add a file to be minified.

     *

     * @param string|string[] $data

     *

     * @return static

     *

     * @throws IOException

     */

    public function addFile($data /* $data = null, ... */)

    {

        // bogus "usage" of parameter $data: scrutinizer warns this variable is

        // not used (we're using func_get_args instead to support overloading),

        // but it still needs to be defined because it makes no sense to have

        // this function without argument :)

        $args = array($data) + func_get_args();

        // this method can be overloaded

        foreach ($args as $path) {

            if (is_array($path)) {

                call_user_func_array(array($this, 'addFile'), $path);

                continue;

            }

            // redefine var

            $path = (string) $path;

            // check if we can read the file

            if (!$this->canImportFile($path)) {

                throw new IOException('The file "' . $path . '" could not be opened for reading. Check if PHP has enough permissions.');

            }

            $this->add($path);

        }

        return $this;

    }

    /**

     * Minify the data & (optionally) saves it to a file.

     *

     * @param string[optional] $path Path to write the data to

     *

     * @return string The minified data

     */

    public function minify($path = null)

    {

        $content = $this->execute($path);

        // save to path

        if ($path !== null) {

            $this->save($content, $path);

        }

        return $content;

    }

    /**

     * Minify & gzip the data & (optionally) saves it to a file.

     *

     * @param string[optional] $path  Path to write the data to

     * @param int[optional]    $level Compression level, from 0 to 9

     *

     * @return string The minified & gzipped data

     */

    public function gzip($path = null, $level = 9)

    {

        $content = $this->execute($path);

        $content = gzencode($content, $level, FORCE_GZIP);

        // save to path

        if ($path !== null) {

            $this->save($content, $path);

        }

        return $content;

    }

    /**

     * Minify the data & write it to a CacheItemInterface object.

     *

     * @param CacheItemInterface $item Cache item to write the data to

     *

     * @return CacheItemInterface Cache item with the minifier data

     */

    public function cache(CacheItemInterface $item)

    {

        $content = $this->execute();

        $item->set($content);

        return $item;

    }

    /**

     * Minify the data.

     *

     * @param string[optional] $path Path to write the data to

     *

     * @return string The minified data

     */

    abstract public function execute($path = null);

    /**

     * Load data.

     *

     * @param string $data Either a path to a file or the content itself

     *

     * @return string

     */

    protected function load($data)

    {

        // check if the data is a file

        if ($this->canImportFile($data)) {

            $data = file_get_contents($data);

            // strip BOM, if any

            if (substr($data, 0, 3) == "\xef\xbb\xbf") {

                $data = substr($data, 3);

            }

        }

        return $data;

    }

    /**

     * Save to file.

     *

     * @param string $content The minified data

     * @param string $path    The path to save the minified data to

     *

     * @throws IOException

     */

    protected function save($content, $path)

    {

        $handler = $this->openFileForWriting($path);

        $this->writeToFile($handler, $content);

        @fclose($handler);

    }

    /**

     * Register a pattern to execute against the source content.

     *

     * If $replacement is a string, it must be plain text. Placeholders like $1 or \2 don't work.

     * If you need that functionality, use a callback instead.

     *

     * @param string          $pattern     PCRE pattern

     * @param string|callable $replacement Replacement value for matched pattern

     */

    protected function registerPattern($pattern, $replacement = '')

    {

        // study the pattern, we'll execute it more than once

        $pattern .= 'S';

        $this->patterns[] = array($pattern, $replacement);

    }

    /**

     * Both JS and CSS use the same form of multi-line comment, so putting the common code here.

     */

    protected function stripMultilineComments()

    {

        // First extract comments we want to keep, so they can be restored later

        // PHP only supports $this inside anonymous functions since 5.4

        $minifier = $this;

        $callback = function ($match) use ($minifier) {

            $count = count($minifier->extracted);

            $placeholder = '/*'.$count.'*/';

            $minifier->extracted[$placeholder] = $match[0];

            return $placeholder;

        };

        $this->registerPattern('/

            # optional newline

            \n?

            # start comment

            \/\*

            # comment content

            (?:

                # either starts with an !

                !

            |

                # or, after some number of characters which do not end the comment

                (?:(?!\*\/).)*?

                # there is either a @license or @preserve tag

                @(?:license|preserve)

            )

            # then match to the end of the comment

            .*?\*\/\n?

            /ixs', $callback);

        // Then strip all other comments

        $this->registerPattern('/\/\*.*?\*\//s', '');

    }

    /**

     * We can't "just" run some regular expressions against JavaScript: it's a

     * complex language. E.g. having an occurrence of // xyz would be a comment,

     * unless it's used within a string. Of you could have something that looks

     * like a 'string', but inside a comment.

     * The only way to accurately replace these pieces is to traverse the JS one

     * character at a time and try to find whatever starts first.

     *

     * @param string $content The content to replace patterns in

     *

     * @return string The (manipulated) content

     */

    protected function replace($content)

    {

        $contentLength = strlen($content);

        $output = '';

        $processedOffset = 0;

        $positions = array_fill(0, count($this->patterns), -1);

        $matches = array();

        while ($processedOffset < $contentLength) {

            // find first match for all patterns

            foreach ($this->patterns as $i => $pattern) {

                list($pattern, $replacement) = $pattern;

                // we can safely ignore patterns for positions we've unset earlier,

                // because we know these won't show up anymore

                if (array_key_exists($i, $positions) == false) {

                    continue;

                }

                // no need to re-run matches that are still in the part of the

                // content that hasn't been processed

                if ($positions[$i] >= $processedOffset) {

                    continue;

                }

                $match = null;

                if (preg_match($pattern, $content, $match, PREG_OFFSET_CAPTURE, $processedOffset)) {

                    $matches[$i] = $match;

                    // we'll store the match position as well; that way, we

                    // don't have to redo all preg_matches after changing only

                    // the first (we'll still know where those others are)

                    $positions[$i] = $match[0][1];

                } else {

                    // if the pattern couldn't be matched, there's no point in

                    // executing it again in later runs on this same content;

                    // ignore this one until we reach end of content

                    unset($matches[$i], $positions[$i]);

                }

            }

            // no more matches to find: everything's been processed, break out

            if (!$matches) {

                // output the remaining content

                $output .= substr($content, $processedOffset);

                break;

            }

            // see which of the patterns actually found the first thing (we'll

            // only want to execute that one, since we're unsure if what the

            // other found was not inside what the first found)

            $matchOffset = min($positions);

            $firstPattern = array_search($matchOffset, $positions);

            $match = $matches[$firstPattern];

            // execute the pattern that matches earliest in the content string

            list(, $replacement) = $this->patterns[$firstPattern];

            // add the part of the input between $processedOffset and the first match;

            // that content wasn't matched by anything

            $output .= substr($content, $processedOffset, $matchOffset - $processedOffset);

            // add the replacement for the match

            $output .= $this->executeReplacement($replacement, $match);

            // advance $processedOffset past the match

            $processedOffset = $matchOffset + strlen($match[0][0]);

        }

        return $output;

    }

    /**

     * If $replacement is a callback, execute it, passing in the match data.

     * If it's a string, just pass it through.

     *

     * @param string|callable $replacement Replacement value

     * @param array           $match       Match data, in PREG_OFFSET_CAPTURE form

     *

     * @return string

     */

    protected function executeReplacement($replacement, $match)

    {

        if (!is_callable($replacement)) {

            return $replacement;

        }

        // convert $match from the PREG_OFFSET_CAPTURE form to the form the callback expects

        foreach ($match as &$matchItem) {

            $matchItem = $matchItem[0];

        }

        return $replacement($match);

    }

    /**

     * Strings are a pattern we need to match, in order to ignore potential

     * code-like content inside them, but we just want all of the string

     * content to remain untouched.

     *

     * This method will replace all string content with simple STRING#

     * placeholder text, so we've rid all strings from characters that may be

     * misinterpreted. Original string content will be saved in $this->extracted

     * and after doing all other minifying, we can restore the original content

     * via restoreStrings().

     *

     * @param string[optional] $chars

     * @param string[optional] $placeholderPrefix

     */

    protected function extractStrings($chars = '\'"', $placeholderPrefix = '')

    {

        // PHP only supports $this inside anonymous functions since 5.4

        $minifier = $this;

        $callback = function ($match) use ($minifier, $placeholderPrefix) {

            // check the second index here, because the first always contains a quote

            if ($match[2] === '') {

                /*

                 * Empty strings need no placeholder; they can't be confused for

                 * anything else anyway.

                 * But we still needed to match them, for the extraction routine

                 * to skip over this particular string.

                 */

                return $match[0];

            }

            $count = count($minifier->extracted);

            $placeholder = $match[1] . $placeholderPrefix . $count . $match[1];

            $minifier->extracted[$placeholder] = $match[1] . $match[2] . $match[1];

            return $placeholder;

        };

        /*

         * The \\ messiness explained:

         * * Don't count ' or " as end-of-string if it's escaped (has backslash

         * in front of it)

         * * Unless... that backslash itself is escaped (another leading slash),

         * in which case it's no longer escaping the ' or "

         * * So there can be either no backslash, or an even number

         * * multiply all of that times 4, to account for the escaping that has

         * to be done to pass the backslash into the PHP string without it being

         * considered as escape-char (times 2) and to get it in the regex,

         * escaped (times 2)

         */

        $this->registerPattern('/([' . $chars . '])(.*?(?<!\\\\)(\\\\\\\\)*+)\\1/s', $callback);

    }

    /**

     * This method will restore all extracted data (strings, regexes) that were

     * replaced with placeholder text in extract*(). The original content was

     * saved in $this->extracted.

     *

     * @param string $content

     *

     * @return string

     */

    protected function restoreExtractedData($content)

    {

        if (!$this->extracted) {

            // nothing was extracted, nothing to restore

            return $content;

        }

        $content = strtr($content, $this->extracted);

        $this->extracted = array();

        return $content;

    }

    /**

     * Check if the path is a regular file and can be read.

     *

     * @param string $path

     *

     * @return bool

     */

    protected function canImportFile($path)

    {

        $parsed = parse_url($path);

        if (

            // file is elsewhere

            isset($parsed['host']) ||

            // file responds to queries (may change, or need to bypass cache)

            isset($parsed['query'])

        ) {

            return false;

        }

        return strlen($path) < PHP_MAXPATHLEN && @is_file($path) && is_readable($path);

    }

    /**

     * Attempts to open file specified by $path for writing.

     *

     * @param string $path The path to the file

     *

     * @return resource Specifier for the target file

     *

     * @throws IOException

     */

    protected function openFileForWriting($path)

    {

        if ($path === '' || ($handler = @fopen($path, 'w')) === false) {

            throw new IOException('The file "' . $path . '" could not be opened for writing. Check if PHP has enough permissions.');

        }

        return $handler;

    }

    /**

     * Attempts to write $content to the file specified by $handler. $path is used for printing exceptions.

     *

     * @param resource $handler The resource to write to

     * @param string   $content The content to write

     * @param string   $path    The path to the file (for exception printing only)

     *

     * @throws IOException

     */

    protected function writeToFile($handler, $content, $path = '')

    {

        if (

            !is_resource($handler) ||

            ($result = @fwrite($handler, $content)) === false ||

            ($result < strlen($content))

        ) {

            throw new IOException('The file "' . $path . '" could not be written to. Check your disk space and file permissions.');

        }

    }

    protected static function str_replace_first($search, $replace, $subject)

    {

        $pos = strpos($subject, $search);

        if ($pos !== false) {

            return substr_replace($subject, $replace, $pos, strlen($search));

        }

        return $subject;

    }

}