<?php
/**
 * modified PHP implementation of Matthias Mullie's Abstract minifier class.
 *
 * @author Matthias Mullie <minify@mullie.eu>
 * @copyright Copyright (c) 2012, Matthias Mullie. All rights reserved
 * @license MIT License
 */

namespace LiteSpeed\Lib\CSS_JS_MIN\Minify;

use LiteSpeed\Lib\CSS_JS_MIN\Minify\Exception\IOException;

defined( 'WPINC' ) || exit;

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.
	 *
	 * @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;
		}

		try {
			return strlen( $path ) < PHP_MAXPATHLEN && @is_file( $path ) && is_readable( $path );
		}
		// catch openbasedir exceptions which are not caught by @ on is_file()
		catch ( \Exception $e ) {
			return false;
		}
	}

	/**
	 * 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;
	}
}
