<?php
/**
 * JSMin.php - modified PHP implementation of Douglas Crockford's JSMin.
 *
 * <code>
 * $minifiedJs = JSMin::minify($js);
 * </code>
 *
 * This is a modified port of jsmin.c. Improvements:
 *
 * Does not choke on some regexp literals containing quote characters. E.g. /'/
 *
 * Spaces are preserved after some add/sub operators, so they are not mistakenly
 * converted to post-inc/dec. E.g. a + ++b -> a+ ++b
 *
 * Preserves multi-line comments that begin with /*!
 *
 * PHP 5 or higher is required.
 *
 * Permission is hereby granted to use this version of the library under the
 * same terms as jsmin.c, which has the following license:
 *
 * --
 * Copyright (c) 2002 Douglas Crockford  (www.crockford.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * The Software shall be used for Good, not Evil.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * --
 *
 * @package JSMin
 * @author Ryan Grove <ryan@wonko.com> (PHP port)
 * @author Steve Clay <steve@mrclay.org> (modifications + cleanup)
 * @author Andrea Giammarchi <http://www.3site.eu> (spaceBeforeRegExp)
 * @copyright 2002 Douglas Crockford <douglas@crockford.com> (jsmin.c)
 * @copyright 2008 Ryan Grove <ryan@wonko.com> (PHP port)
 * @license http://opensource.org/licenses/mit-license.php MIT License
 * @link http://code.google.com/p/jsmin-php/
 */
namespace LiteSpeed\Lib ;

defined( 'WPINC' ) || exit ;

class JSMin
{
	const ORD_LF            = 10;
	const ORD_SPACE         = 32;
	const ACTION_KEEP_A     = 1;
	const ACTION_DELETE_A   = 2;
	const ACTION_DELETE_A_B = 3;

	protected $a           = "\n";
	protected $b           = '';
	protected $input       = '';
	protected $inputIndex  = 0;
	protected $inputLength = 0;
	protected $lookAhead   = null;
	protected $output      = '';
	protected $lastByteOut  = '';
	protected $keptComment = '';

	/**
	 * Minify Javascript.
	 *
	 * @param string $js Javascript to be minified
	 *
	 * @return string
	 */
	public static function minify($js)
	{
		$jsmin = new JSMin($js);
		return $jsmin->min();
	}

	/**
	 * @param string $input
	 */
	public function __construct($input)
	{
		$this->input = $input;
	}

	/**
	 * Perform minification, return result
	 *
	 * @return string
	 */
	public function min()
	{
		if ($this->output !== '') { // min already run
			return $this->output;
		}

		$mbIntEnc = null;
		if (function_exists('mb_strlen') && ((int)ini_get('mbstring.func_overload') & 2)) {
			$mbIntEnc = mb_internal_encoding();
			mb_internal_encoding('8bit');
		}

		if (isset($this->input[0]) && $this->input[0] === "\xef") {
			$this->input = substr($this->input, 3);
		}

		$this->input = str_replace("\r\n", "\n", $this->input);
		$this->inputLength = strlen($this->input);

		$this->action(self::ACTION_DELETE_A_B);

		while ($this->a !== null) {
			// determine next command
			$command = self::ACTION_KEEP_A; // default
			if ($this->a === ' ') {
				if (($this->lastByteOut === '+' || $this->lastByteOut === '-')
						&& ($this->b === $this->lastByteOut)) {
					// Don't delete this space. If we do, the addition/subtraction
					// could be parsed as a post-increment
				} elseif (! $this->isAlphaNum($this->b)) {
					$command = self::ACTION_DELETE_A;
				}
			} elseif ($this->a === "\n") {
				if ($this->b === ' ') {
					$command = self::ACTION_DELETE_A_B;

					// in case of mbstring.func_overload & 2, must check for null b,
					// otherwise mb_strpos will give WARNING
				} elseif ($this->b === null
						  || (false === strpos('{[(+-!~', $this->b)
							  && ! $this->isAlphaNum($this->b))) {
					$command = self::ACTION_DELETE_A;
				}
			} elseif (! $this->isAlphaNum($this->a)) {
				if ($this->b === ' '
					|| ($this->b === "\n"
						&& (false === strpos('}])+-"\'', $this->a)))) {
					$command = self::ACTION_DELETE_A_B;
				}
			}
			$this->action($command);
		}
		$this->output = trim($this->output);

		if ($mbIntEnc !== null) {
			mb_internal_encoding($mbIntEnc);
		}
		return $this->output;
	}

	/**
	 * ACTION_KEEP_A = Output A. Copy B to A. Get the next B.
	 * ACTION_DELETE_A = Copy B to A. Get the next B.
	 * ACTION_DELETE_A_B = Get the next B.
	 *
	 * @param int $command
	 * @throws UnterminatedRegExpException|UnterminatedStringException
	 */
	protected function action($command)
	{
		// make sure we don't compress "a + ++b" to "a+++b", etc.
		if ($command === self::ACTION_DELETE_A_B
			&& $this->b === ' '
			&& ($this->a === '+' || $this->a === '-')) {
			// Note: we're at an addition/substraction operator; the inputIndex
			// will certainly be a valid index
			if ($this->input[$this->inputIndex] === $this->a) {
				// This is "+ +" or "- -". Don't delete the space.
				$command = self::ACTION_KEEP_A;
			}
		}

		switch ($command) {
			case self::ACTION_KEEP_A: // 1
				$this->output .= $this->a;

				if ($this->keptComment) {
					$this->output = rtrim($this->output, "\n");
					$this->output .= $this->keptComment;
					$this->keptComment = '';
				}

				$this->lastByteOut = $this->a;

				// fallthrough intentional
			case self::ACTION_DELETE_A: // 2
				$this->a = $this->b;
				if ($this->a === "'" || $this->a === '"') { // string literal
					$str = $this->a; // in case needed for exception
					for(;;) {
						$this->output .= $this->a;
						$this->lastByteOut = $this->a;

						$this->a = $this->get();
						if ($this->a === $this->b) { // end quote
							break;
						}
						if ($this->isEOF($this->a)) {
							$byte = $this->inputIndex - 1;
							throw new \Exception(
								"JSMin: Unterminated String at byte {$byte}: {$str}");
						}
						$str .= $this->a;
						if ($this->a === '\\') {
							$this->output .= $this->a;
							$this->lastByteOut = $this->a;

							$this->a       = $this->get();
							$str .= $this->a;
						}
					}
				}

				// fallthrough intentional
			case self::ACTION_DELETE_A_B: // 3
				$this->b = $this->next();
				if ($this->b === '/' && $this->isRegexpLiteral()) {
					$this->output .= $this->a . $this->b;
					$pattern = '/'; // keep entire pattern in case we need to report it in the exception
					for(;;) {
						$this->a = $this->get();
						$pattern .= $this->a;
						if ($this->a === '[') {
							for(;;) {
								$this->output .= $this->a;
								$this->a = $this->get();
								$pattern .= $this->a;
								if ($this->a === ']') {
									break;
								}
								if ($this->a === '\\') {
									$this->output .= $this->a;
									$this->a = $this->get();
									$pattern .= $this->a;
								}
								if ($this->isEOF($this->a)) {
									throw new \Exception(
										"JSMin: Unterminated set in RegExp at byte "
											. $this->inputIndex .": {$pattern}");
								}
							}
						}

						if ($this->a === '/') { // end pattern
							break; // while (true)
						} elseif ($this->a === '\\') {
							$this->output .= $this->a;
							$this->a = $this->get();
							$pattern .= $this->a;
						} elseif ($this->isEOF($this->a)) {
							$byte = $this->inputIndex - 1;
							throw new \Exception(
								"JSMin: Unterminated RegExp at byte {$byte}: {$pattern}");
						}
						$this->output .= $this->a;
						$this->lastByteOut = $this->a;
					}
					$this->b = $this->next();
				}
			// end case ACTION_DELETE_A_B
		}
	}

	/**
	 * @return bool
	 */
	protected function isRegexpLiteral()
	{
		if (false !== strpos("(,=:[!&|?+-~*{;", $this->a)) {
			// we can't divide after these tokens
			return true;
		}

		// check if first non-ws token is "/" (see starts-regex.js)
		$length = strlen($this->output);
		if ($this->a === ' ' || $this->a === "\n") {
			if ($length < 2) { // weird edge case
				return true;
			}
		}

		// if the "/" follows a keyword, it must be a regexp, otherwise it's best to assume division

		$subject = $this->output . trim($this->a);
		if (!preg_match('/(?:case|else|in|return|typeof)$/', $subject, $m)) {
			// not a keyword
			return false;
		}

		// can't be sure it's a keyword yet (see not-regexp.js)
		$charBeforeKeyword = substr($subject, 0 - strlen($m[0]) - 1, 1);
		if ($this->isAlphaNum($charBeforeKeyword)) {
			// this is really an identifier ending in a keyword, e.g. "xreturn"
			return false;
		}

		// it's a regexp. Remove unneeded whitespace after keyword
		if ($this->a === ' ' || $this->a === "\n") {
			$this->a = '';
		}

		return true;
	}

	/**
	 * Return the next character from stdin. Watch out for lookahead. If the character is a control character,
	 * translate it to a space or linefeed.
	 *
	 * @return string
	 */
	protected function get()
	{
		$c = $this->lookAhead;
		$this->lookAhead = null;
		if ($c === null) {
			// getc(stdin)
			if ($this->inputIndex < $this->inputLength) {
				$c = $this->input[$this->inputIndex];
				$this->inputIndex += 1;
			} else {
				$c = null;
			}
		}
		if (ord($c) >= self::ORD_SPACE || $c === "\n" || $c === null) {
			return $c;
		}
		if ($c === "\r") {
			return "\n";
		}
		return ' ';
	}

	/**
	 * Does $a indicate end of input?
	 *
	 * @param string $a
	 * @return bool
	 */
	protected function isEOF($a)
	{
		return ord($a) <= self::ORD_LF;
	}

	/**
	 * Get next char (without getting it). If is ctrl character, translate to a space or newline.
	 *
	 * @return string
	 */
	protected function peek()
	{
		$this->lookAhead = $this->get();
		return $this->lookAhead;
	}

	/**
	 * Return true if the character is a letter, digit, underscore, dollar sign, or non-ASCII character.
	 *
	 * @param string $c
	 *
	 * @return bool
	 */
	protected function isAlphaNum($c)
	{
		return (preg_match('/^[a-z0-9A-Z_\\$\\\\]$/', $c) || ord($c) > 126);
	}

	/**
	 * Consume a single line comment from input (possibly retaining it)
	 */
	protected function consumeSingleLineComment()
	{
		$comment = '';
		while (true) {
			$get = $this->get();
			$comment .= $get;
			if (ord($get) <= self::ORD_LF) { // end of line reached
				// if IE conditional comment
				if (preg_match('/^\\/@(?:cc_on|if|elif|else|end)\\b/', $comment)) {
					$this->keptComment .= "/{$comment}";
				}
				return;
			}
		}
	}

	/**
	 * Consume a multiple line comment from input (possibly retaining it)
	 *
	 * @throws UnterminatedCommentException
	 */
	protected function consumeMultipleLineComment()
	{
		$this->get();
		$comment = '';
		for(;;) {
			$get = $this->get();
			if ($get === '*') {
				if ($this->peek() === '/') { // end of comment reached
					$this->get();
					if (0 === strpos($comment, '!')) {
						// preserved by YUI Compressor
						if (!$this->keptComment) {
							// don't prepend a newline if two comments right after one another
							$this->keptComment = "\n";
						}
						$this->keptComment .= "/*!" . substr($comment, 1) . "*/\n";
					} else if (preg_match('/^@(?:cc_on|if|elif|else|end)\\b/', $comment)) {
						// IE conditional
						$this->keptComment .= "/*{$comment}*/";
					}
					return;
				}
			} elseif ($get === null) {
				throw new \Exception(
					"JSMin: Unterminated comment at byte {$this->inputIndex}: /*{$comment}");
			}
			$comment .= $get;
		}
	}

	/**
	 * Get the next character, skipping over comments. Some comments may be preserved.
	 *
	 * @return string
	 */
	protected function next()
	{
		$get = $this->get();
		if ($get === '/') {
			switch ($this->peek()) {
				case '/':
					$this->consumeSingleLineComment();
					$get = "\n";
					break;
				case '*':
					$this->consumeMultipleLineComment();
					$get = ' ';
					break;
			}
		}
		return $get;
	}
}
