<?php
  
  /**
   * @author Robin Appelman
   * @copyright 2013 Robin Appelman icewind@owncloud.com
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
   * License as published by the Free Software Foundation; either
   * version 3 of the License, or any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
   *
   * You should have received a copy of the GNU Affero General Public
   * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  namespace OC;
  
  class SyntaxException extends \Exception {
  }
  
  class ArrayParser {
  	const TYPE_NUM = 1;
  	const TYPE_BOOL = 2;
  	const TYPE_STRING = 3;
  	const TYPE_ARRAY = 4;
  
  	function parsePHP($string) {
  		$string = $this->stripPHPTags($string);
  		$string = $this->stripAssignAndReturn($string);
  		return $this->parse($string);
  	}
  
  	function stripPHPTags($string) {
  		$string = trim($string);
  		if (substr($string, 0, 5) === '<?php') {
  			$string = substr($string, 5);
  		}
  		if (substr($string, -2) === '?>') {
  			$string = substr($string, 0, -2);
  		}
  		return $string;
  	}
  
  	function stripAssignAndReturn($string) {
  		$string = trim($string);
  		if (substr($string, 0, 6) === 'return') {
  			$string = substr($string, 6);
  		}
  		if (substr($string, 0, 1) === '$') {
  			list(, $string) = explode('=', $string, 2);
  		}
  		return $string;
  	}
  
  	function parse($string) {
  		$string = trim($string);
  		$string = trim($string, ';');
  		switch ($this->getType($string)) {
  			case self::TYPE_NUM:
  				return $this->parseNum($string);
  			case self::TYPE_BOOL:
  				return $this->parseBool($string);
  			case self::TYPE_STRING:
  				return $this->parseString($string);
  			case self::TYPE_ARRAY:
  				return $this->parseArray($string);
  		}
  		return null;
  	}
  
  	function getType($string) {
  		$string = strtolower($string);
  		$first = substr($string, 0, 1);
  		$last = substr($string, -1, 1);
  		$arrayFirst = substr($string, 0, 5);
  		if (($first === '"' or $first === "'") and ($last === '"' or $last === "'")) {
  			return self::TYPE_STRING;
  		} elseif ($string === 'false' or $string === 'true') {
  			return self::TYPE_BOOL;
  		} elseif ($arrayFirst === 'array' and $last === ')') {
  			return self::TYPE_ARRAY;
  		} else {
  			return self::TYPE_NUM;
  		}
  	}
  
  	function parseString($string) {
  		return substr($string, 1, -1);
  	}
  
  	function parseNum($string) {
  		return intval($string);
  	}
  
  	function parseBool($string) {
  		$string = strtolower($string);
  		return $string === 'true';
  	}
  
  	function parseArray($string) {
  		$body = substr($string, 5);
  		$body = trim($body);
  		$body = substr($body, 1, -1);
  		$items = $this->splitArray($body);
  		$result = array();
  		$lastKey = -1;
  		foreach ($items as $item) {
  			$item = trim($item);
  			if ($item) {
  				if (strpos($item, '=>')) {
  					list($key, $value) = explode('=>', $item, 2);
  					$key = $this->parse($key);
  					$value = $this->parse($value);
  				} else {
  					$key = ++$lastKey;
  					$value = $item;
  				}
  
  				if (is_numeric($key)) {
  					$lastKey = $key;
  				}
  				$result[$key] = $value;
  			}
  		}
  		return $result;
  	}
  
  	function splitArray($body) {
  		$inSingleQuote = false;//keep track if we are inside quotes
  		$inDoubleQuote = false;
  		$bracketDepth = 0;//keep track if we are inside brackets
  		$parts = array();
  		$start = 0;
  		$escaped = false;//keep track if we are after an escape character
  		$skips = array();//keep track of the escape characters we need to remove from the result
  		if (substr($body, -1, 1) !== ',') {
  			$body .= ',';
  		}
  		for ($i = 0; $i < strlen($body); $i++) {
  			$char = substr($body, $i, 1);
  			if ($char === '\\') {
  				if ($escaped) {
  					array_unshift($skips, $i - 1);
  				}
  				$escaped = !$escaped;
  			} else {
  				if ($char === '"' and !$inSingleQuote) {
  					if ($escaped) {
  						array_unshift($skips, $i - 1);
  					} else {
  						$inDoubleQuote = !$inDoubleQuote;
  					}
  				} elseif ($char === "'" and !$inDoubleQuote) {
  					if ($escaped) {
  						array_unshift($skips, $i - 1);
  					} else {
  						$inSingleQuote = !$inSingleQuote;
  					}
  				} elseif (!$inDoubleQuote and !$inSingleQuote) {
  					if ($char === '(') {
  						$bracketDepth++;
  					} elseif ($char === ')') {
  						if ($bracketDepth <= 0) {
  							throw new SyntaxException;
  						} else {
  							$bracketDepth--;
  						}
  					} elseif ($bracketDepth === 0 and $char === ',') {
  						$part = substr($body, $start, $i - $start);
  						foreach ($skips as $skip) {
  							$part = substr($part, 0, $skip - $start) . substr($part, $skip - $start + 1);
  						}
  						$parts[] = $part;
  						$start = $i + 1;
  						$skips = array();
  					}
  				}
  				$escaped = false;
  			}
  		}
  		return $parts;
  	}
  }