<?php
namespace mp_timetable\classes\libs;
/**
 * GUMP - A fast, extensible PHP input validation class.
 *
 * @author      Sean Nieuwoudt (http://twitter.com/SeanNieuwoudt)
 * @copyright   Copyright (c) 2015 wixelhq.com
 *
 * @link        http://github.com/Wixel/GUMP
 *
 * @version     1.0
 */
class GUMP {
	// Validation rules for execution
	protected $validation_rules = array();

	// Filter rules for execution
	protected $filter_rules = array();

	// Instance attribute containing errors from last run
	protected $errors = array();

	// Contain readable field names that have been set manually
	protected static $fields = array();

	// Custom validation methods
	protected static $validation_methods = array();

	// Customer filter methods
	protected static $filter_methods = array();

	// ** ------------------------- Validation Data ------------------------------- ** //

	public static $basic_tags = '<br><p><a><strong><b><i><em><img><blockquote><code><dd><dl><hr><h1><h2><h3><h4><h5><h6><label><ul><li><span><sub><sup>';

	public static $en_noise_words = "about,after,all,also,an,and,another,any,are,as,at,be,because,been,before,
				  				  	 being,between,both,but,by,came,can,come,could,did,do,each,for,from,get,
				  				  	 got,has,had,he,have,her,here,him,himself,his,how,if,in,into,is,it,its,it's,like,
			      				  	 make,many,me,might,more,most,much,must,my,never,now,of,on,only,or,other,
				  				  	 our,out,over,said,same,see,should,since,some,still,such,take,than,that,
				  				  	 the,their,them,then,there,these,they,this,those,through,to,too,under,up,
				  				  	 very,was,way,we,well,were,what,where,which,while,who,with,would,you,your,a,
				  				  	 b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,$,1,2,3,4,5,6,7,8,9,0,_";

	// field characters below will be replaced with a space.
	protected $fieldCharsToRemove = array('_', '-');

	// ** ------------------------- Validation Helpers ---------------------------- ** //

	/**
	 * Shorthand method for inline validation.
	 *
	 * @param array $data The data to be validated
	 * @param array $validators The GUMP validators
	 *
	 * @return mixed True(boolean) or the array of error messages
	 */
	public static function is_valid(array $data, array $validators) {
		$gump = new self();

		$gump->validation_rules($validators);

		if ($gump->run($data) === false) {
			return $gump->get_readable_errors(false);
		} else {
			return true;
		}
	}

	/**
	 * Shorthand method for running only the data filters.
	 *
	 * @param array $data
	 * @param array $filters
	 *
	 * @return mixed
	 */
	public static function filter_input(array $data, array $filters) {
		$gump = new self();

		return $gump->filter($data, $filters);
	}

	/**
	 * Magic method to generate the validation error messages.
	 *
	 * @return string
	 */
	public function __toString() {
		return $this->get_readable_errors(true);
	}

	/**
	 * Perform XSS clean to prevent cross site scripting.
	 *
	 * @static
	 *
	 * @param array $data
	 *
	 * @return array
	 */
	public static function xss_clean(array $data) {
		foreach ($data as $k => $v) {
			$data[$k] = static::polyfill_filter_var_string($v);
		}

		return $data;
	}

	/**
	 * Adds a custom validation rule using a callback function.
	 *
	 * @param string $rule
	 * @param callable $callback
	 *
	 * @return bool
	 *
	 * @throws Exception
	 */
	public static function add_validator($rule, $callback) {
		$method = 'validate_' . $rule;

		if (method_exists(__CLASS__, $method) || isset(self::$validation_methods[$rule])) {
			throw new \Exception("Validator rule '$rule' already exists.");
		}

		self::$validation_methods[$rule] = $callback;

		return true;
	}

	/**
	 * Adds a custom filter using a callback function.
	 *
	 * @param string $rule
	 * @param callable $callback
	 *
	 * @return bool
	 *
	 * @throws Exception
	 */
	public static function add_filter($rule, $callback) {
		$method = 'filter_' . $rule;

		if (method_exists(__CLASS__, $method) || isset(self::$filter_methods[$rule])) {
			throw new \Exception("Filter rule '$rule' already exists.");
		}

		self::$filter_methods[$rule] = $callback;

		return true;
	}

	/**
	 * Helper method to extract an element from an array safely
	 *
	 * @param mixed $key
	 * @param array $array
	 * @param mixed $default
	 *
	 * @return mixed
	 */
	public static function field($key, array $array, $default = null) {
		if (!is_array($array)) {
			return null;
		}

		if (isset($array[$key])) {
			return $array[$key];
		} else {
			return $default;
		}
	}

	/**
	 * Getter/Setter for the validation rules.
	 *
	 * @param array $rules
	 *
	 * @return array
	 */
	public function validation_rules(array $rules = array()) {
		if (empty($rules)) {
			return $this->validation_rules;
		}

		$this->validation_rules = $rules;
	}

	/**
	 * Getter/Setter for the filter rules.
	 *
	 * @param array $rules
	 *
	 * @return array
	 */
	public function filter_rules(array $rules = array()) {
		if (empty($rules)) {
			return $this->filter_rules;
		}

		$this->filter_rules = $rules;
	}

	/**
	 * Run the filtering and validation after each other.
	 *
	 * @param array $data
	 * @param bool $check_fields
	 *
	 * @return array
	 *
	 * @throws Exception
	 */
	public function run(array $data, $check_fields = false) {
		$data = $this->filter($data, $this->filter_rules());

		$validated = $this->validate(
			$data, $this->validation_rules()
		);

		if ($check_fields === true) {
			$this->check_fields($data);
		}

		if ($validated !== true) {
			return false;
		}

		return $data;
	}

	/**
	 * Ensure that the field counts match the validation rule counts.
	 *
	 * @param array $data
	 */
	private function check_fields(array $data) {
		$ruleset = $this->validation_rules();
		$mismatch = array_diff_key($data, $ruleset);
		$fields = array_keys($mismatch);

		foreach ($fields as $field) {
			$this->errors[] = array(
				'field' => $field,
				'value' => $data[$field],
				'rule' => 'mismatch',
				'param' => null,
			);
		}
	}

	/**
	 * Sanitize the input data.
	 *
	 * @param array $input
	 * @param null $fields
	 * @param bool $utf8_encode
	 *
	 * @return array
	 */
	public function sanitize(array $input, array $fields = array(), $utf8_encode = true) {

		if (empty($fields)) {
			$fields = array_keys($input);
		}

		$return = array();

		foreach ($fields as $field) {
			if (!isset($input[$field])) {
				continue;
			} else {
				$value = $input[$field];
				if (is_array($value)) {
					$value = null;
				}
				if (is_string($value)) {

					if (strpos($value, "\r") !== false) {
						$value = trim($value);
					}

					if (function_exists('iconv') && function_exists('mb_detect_encoding') && $utf8_encode) {
						$current_encoding = mb_detect_encoding($value);

						if ($current_encoding != 'UTF-8' && $current_encoding != 'UTF-16') {
							$value = iconv($current_encoding, 'UTF-8', $value);
						}
					}

					$value = static::polyfill_filter_var_string($value);
				}

				$return[$field] = $value;
			}
		}

		return $return;
	}

	/**
	 * Return the error array from the last validation run.
	 *
	 * @return array
	 */
	public function errors() {
		return $this->errors;
	}

	/**
	 * Perform data validation against the provided ruleset.
	 *
	 * @param mixed $input
	 * @param array $ruleset
	 *
	 * @return mixed
	 *
	 * @throws Exception
	 */
	public function validate(array $input, array $ruleset) {
		$this->errors = array();

		foreach ($ruleset as $field => $rules) {

			$rules = explode('|', $rules);

			if (in_array('required', $rules) || (isset($input[$field]) && !is_array($input[$field]))) {
				foreach ($rules as $rule) {
					$method = null;
					$param = null;

					// Check if we have rule parameters
					if (strstr($rule, ',') !== false) {
						$rule = explode(',', $rule);
						$method = 'validate_' . $rule[0];
						$param = $rule[1];
						$rule = $rule[0];
					} else {
						$method = 'validate_' . $rule;
					}

					//self::$validation_methods[$rule] = $callback;

					if (is_callable(array($this, $method))) {
						$result = $this->$method(
							$field, $input, $param
						);

						if (is_array($result)) {
							$this->errors[] = $result;
						}
					} elseif (isset(self::$validation_methods[$rule])) {

						$result = call_user_func(self::$validation_methods[$rule], $field, $input, $param);

						if ($result === false) {
							$this->errors[] = array(
								'field' => $field,
								'value' => $input,
								'rule' => self::$validation_methods[$rule],
								'param' => $param,
							);
						}

					} else {
						throw new \Exception("Validator method '$method' does not exist.");
					}
				}
			}
		}

		return (count($this->errors) > 0) ? $this->errors : true;
	}

	/**
	 * Overloadable method to invoke validation.
	 *
	 * @param array $input
	 * @param $rules
	 * @param $field
	 *
	 * @return bool
	 */
	protected function shouldRunValidation(array $input, $rules, $field) {
		return in_array('required', $rules) || (isset($input[$field]) && trim($input[$field]) != '');
	}

	/**
	 * Set a readable name for a specified field names.
	 *
	 * @param string $field
	 * @param string $readable_name
	 */
	public static function set_field_name($field, $readable_name) {
		self::$fields[$field] = $readable_name;
	}

	/**
	 * Set readable name for specified fields in an array.
	 *
	 * Usage:
	 *
	 * GUMP::set_field_names(array(
	 *    "name" => "My Lovely Name",
	 *    "username" => "My Beloved Username",
	 * ));
	 *
	 * @param array $array
	 */
	public static function set_field_names(array $array) {
		foreach ($array as $field => $readable_name) {
			self::$fields[$field] = $readable_name;
		}
	}

	/**
	 * Process the validation errors and return human readable error messages.
	 *
	 * @param bool $convert_to_string = false
	 * @param string $field_class
	 * @param string $error_class
	 *
	 * @return array
	 * @return string
	 */
	public function get_readable_errors($convert_to_string = false, $field_class = 'gump-field', $error_class = 'gump-error-message') {
		if (empty($this->errors)) {
			return ($convert_to_string) ? null : array();
		}

		$resp = array();

		foreach ($this->errors as $e) {
			$field = ucwords(str_replace($this->fieldCharsToRemove, chr(32), $e['field']));
			$param = $e['param'];

			// Let's fetch explicit field names if they exist
			if (array_key_exists($e['field'], self::$fields)) {
				$field = self::$fields[$e['field']];
			}

			switch ($e['rule']) {
				case 'mismatch' :
					$resp[] = sprintf( 'There is no validation rule for <span class="%1$s">%2$s</span>', $field_class, $field );
					break;
				case 'validate_required' :
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field is required', $field_class, $field );
					break;
				case 'validate_valid_email':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field is required to be a valid email address', $field_class, $field );
					break;
				case 'validate_max_len':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be %d or shorter in length', $field_class, $field, $param );
					break;
				case 'validate_min_len':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be %d or longer in length', $field_class, $field, $param );
					break;
				case 'validate_exact_len':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be exactly %d characters in length', $field_class, $field, $param );
					break;
				case 'validate_alpha':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain alpha characters(a-z)', $field_class, $field );
					break;
				case 'validate_alpha_numeric':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain alpha-numeric characters', $field_class, $field );
					break;
				case 'validate_alpha_dash':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain alpha characters &amp; dashes', $field_class, $field );
					break;
				case 'validate_numeric':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain numeric characters', $field_class, $field );
					break;
				case 'validate_integer':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain a numeric value', $field_class, $field );
					break;
				case 'validate_boolean':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain a true or false value', $field_class, $field );
					break;
				case 'validate_float':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field may only contain a float value', $field_class, $field );
					break;
				case 'validate_valid_url':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field is required to be a valid URL', $field_class, $field );
					break;
				case 'validate_url_exists':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> URL does not exist', $field_class, $field );
					break;
				case 'validate_valid_ip':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to contain a valid IP address', $field_class, $field );
					break;
				case 'validate_valid_cc':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to contain a valid credit card number', $field_class, $field );
					break;
				case 'validate_valid_name':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to contain a valid human name', $field_class, $field );
					break;
				case 'validate_contains':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to contain one of these values:', $field_class, $field ) . ' ' . implode(', ', $param);
					break;
				case 'validate_contains_list':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs contain a value from its drop down list', $field_class, $field );
					break;
				case 'validate_doesnt_contain_list':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field contains a value that is not accepted', $field_class, $field );
					break;
				case 'validate_street_address':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be a valid street address', $field_class, $field );
					break;
				case 'validate_date':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be a valid date', $field_class, $field );
					break;
				case 'validate_min_numeric':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be a numeric value, equal to, or higher than', $field_class, $field ) . $param;
					break;
				case 'validate_max_numeric':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to be a numeric value, equal to, or lower than', $field_class, $field ) . ' ' . $param;
					break;
				case 'validate_starts':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to start with', $field_class, $field ) . ' ' . $param;
					break;
				case 'validate_extension':
					$resp[] = sprintf( 'The <span class"%1$s">%2$s</span> field can have the following extensions', $field_class, $field ) . ' '. $param;
					break;
				case 'validate_required_file':
					$resp[] = sprintf( 'The <span class"%1$s">%2$s</span> field is required', $field_class, $field ) .' ' . $param;
					break;
				case 'validate_equalsfield':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field does not equal %d field', $field_class, $field, $param ) ;
					break;
				case 'validate_min_age':
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field needs to have an age greater than or equal to', $field_class, $field ) . ' '. $param;;
					break;
				default:
					$resp[] = sprintf( 'The <span class="%1$s">%2$s</span> field is invalid', $field_class, $field );
			}
		}

		if (!$convert_to_string) {
			return $resp;
		} else {
			$buffer = '';
			foreach ($resp as $s) {
				$buffer .= "<span class=\"$error_class\">$s</span>";
			}

			return $buffer;
		}
	}

	/**
	 * Process the validation errors and return an array of errors with field names as keys.
	 *
	 * @param $convert_to_string
	 *
	 * @return array | null (if empty)
	 */
	public function get_errors_array($convert_to_string = null) {
		if (empty($this->errors)) {
			return ($convert_to_string) ? null : array();
		}

		$resp = array();

		foreach ($this->errors as $e) {
			$field = ucwords(str_replace(array('_', '-'), chr(32), $e['field']));
			$param = $e['param'];

			// Let's fetch explicit field names if they exist
			if (array_key_exists($e['field'], self::$fields)) {
				$field = self::$fields[$e['field']];
			}

			switch ($e['rule']) {
				case 'mismatch' :
					$resp[$field] = 'There is no validation rule for' . ' ' . $field;
					break;
				case 'validate_required':
					$resp[$field] = sprintf( 'The %s field is required', $field);
					break;
				case 'validate_valid_email':
					$resp[$field] = sprintf( 'The %s field is required to be a valid email address', $field);
					break;
				case 'validate_max_len':
					$resp[$field] = sprintf( 'The %s field needs to be %d or shorter in length', $field, $param);
					break;
				case 'validate_min_len':
					$resp[$field] = sprintf( 'The %s field needs to be %d or longer in length', $field, $param);
					break;
				case 'validate_exact_len':
					$resp[$field] = sprintf( 'The %s field needs to be exactly %d characters in length', $field, $param);
					break;
				case 'validate_alpha':
					$resp[$field] = sprintf( 'The %s field may only contain alpha characters(a-z)', $field);
					break;
				case 'validate_alpha_numeric':
					$resp[$field] = sprintf( 'The %s field may only contain alpha-numeric characters', $field);
					break;
				case 'validate_alpha_dash':
					$resp[$field] = sprintf( 'The %s field may only contain alpha characters &amp; dashes', $field);
					break;
				case 'validate_numeric':
					$resp[$field] = sprintf( 'The %s field may only contain numeric characters', $field);
					break;
				case 'validate_integer':
					$resp[$field] = sprintf( 'The %s field may only contain a numeric value', $field);
					break;
				case 'validate_boolean':
					$resp[$field] = sprintf( 'The %s field may only contain a true or false value', $field);
					break;
				case 'validate_float':
					$resp[$field] = sprintf( 'The %s field may only contain a float value', $field);
					break;
				case 'validate_valid_url':
					$resp[$field] = sprintf( 'The %s field is required to be a valid URL', $field);
					break;
				case 'validate_url_exists':
					$resp[$field] = sprintf( 'The %s URL does not exist', $field);
					break;
				case 'validate_valid_ip':
					$resp[$field] = sprintf( 'The %s field needs to contain a valid IP address', $field);
					break;
				case 'validate_valid_cc':
					$resp[$field] = sprintf( 'The %s field needs to contain a valid credit card number', $field);
					break;
				case 'validate_valid_name':
					$resp[$field] = sprintf( 'The %s field needs to contain a valid human name', $field);
					break;
				case 'validate_contains':
					$resp[$field] = sprintf( 'The %s field needs to contain one of these values:', $field) . ' ' . implode(', ', $param);
					break;
				case 'validate_street_address':
					$resp[$field] = sprintf( 'The %s field needs to be a valid street address', $field);
					break;
				case 'validate_date':
					$resp[$field] = sprintf( 'The %s field needs to be a valid date', $field);
					break;
				case 'validate_min_numeric':
					$resp[$field] = sprintf( 'The %s field needs to be a numeric value, equal to, or higher than %d', $field, $param);
					break;
				case 'validate_max_numeric':
					$resp[$field] = sprintf( 'The %s field needs to be a numeric value, equal to, or lower than %d', $field, $param);
					break;
				case 'validate_min_age':
					$resp[$field] = sprintf( 'The %s field needs to have an age greater than or equal to %d', $field, $param);
					break;
				default:
					$resp[$field] = sprintf( 'The %s field is invalid', $field );
			}
		}

		return $resp;
	}


	/**
	 * Filter the input data according to the specified filter set.
	 *
	 * @param mixed $input
	 * @param array $filterset
	 *
	 * @throws Exception
	 *
	 * @return mixed
	 *
	 * @throws Exception
	 */
	public function filter(array $input, array $filterset) {
		foreach ($filterset as $field => $filters) {
			if (!array_key_exists($field, $input)) {
				continue;
			}

			$filters = explode('|', $filters);

			foreach ($filters as $filter) {
				$params = null;

				if (strstr($filter, ',') !== false) {
					$filter = explode(',', $filter);

					$params = array_slice($filter, 1, count($filter) - 1);

					$filter = $filter[0];
				}

				if (is_callable(array($this, 'filter_' . $filter))) {
					$method = 'filter_' . $filter;
					$input[$field] = $this->$method($input[$field], $params);
				} elseif (function_exists($filter)) {
					$input[$field] = $filter($input[$field]);
				} elseif (isset(self::$filter_methods[$filter])) {
					$input[$field] = call_user_func(self::$filter_methods[$filter], $input[$field], $params);
				} else {
					throw new \Exception("Filter method '$filter' does not exist.");
				}
			}
		}

		return $input;
	}

	// ** ------------------------- Filters --------------------------------------- ** //

	/**
	 * Replace noise words in a string (http://tax.cchgroup.com/help/Avoiding_noise_words_in_your_search.htm).
	 *
	 * Usage: '<index>' => 'noise_words'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_noise_words($value, $params = null) {
		$value = preg_replace('/\s\s+/u', chr(32), $value);

		$value = " $value ";

		$words = explode(',', self::$en_noise_words);

		foreach ($words as $word) {
			$word = trim($word);

			$word = " $word "; // Normalize

			if (stripos($value, $word) !== false) {
				$value = str_ireplace($word, chr(32), $value);
			}
		}

		return trim($value);
	}

	/**
	 * Remove all known punctuation from a string.
	 *
	 * Usage: '<index>' => 'rmpunctuataion'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_rmpunctuation($value, $params = null) {
		return preg_replace("/(?![.=$'€%-])\p{P}/u", '', $value);
	}

	/**
	 * Translate an input string to a desired language [DEPRECIATED].
	 *
	 * Any ISO 639-1 2 character language code may be used
	 *
	 * See: http://www.science.co.il/language/Codes.asp?s=code2
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	/*
	protected function filter_translate($value, $params = NULL)
	{
		$input_lang  = 'en';
		$output_lang = 'en';

		if(is_null($params))
		{
			return $value;
		}

		switch(count($params))
		{
			case 1:
				$input_lang  = $params[0];
				break;
			case 2:
				$input_lang  = $params[0];
				$output_lang = $params[1];
				break;
		}

		$text = urlencode($value);

		$translation = file_get_contents(
			"http://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q={$text}&langpair={$input_lang}|{$output_lang}"
		);

		$json = json_decode($translation, true);

		if($json['responseStatus'] != 200)
		{
			return $value;
		}
		else
		{
			return $json['responseData']['translatedText'];
		}
	}
	*/

	/**
	 * Sanitize the string by removing any script tags.
	 *
	 * Usage: '<index>' => 'sanitize_string'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_sanitize_string($value, $params = null) {
		return self::polyfill_filter_var_string($value);
	}

	private static function polyfill_filter_var_string($value)
	{
		$str = preg_replace('/x00|<[^>]*>?/', '', $value);
		return (string)str_replace(['', ''], ['&#39;', '&#34;'], $str);
	}

	/**
	 * Sanitize the string by urlencoding characters.
	 *
	 * Usage: '<index>' => 'urlencode'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_urlencode($value, $params = null) {
		return filter_var($value, FILTER_SANITIZE_ENCODED);
	}

	/**
	 * Sanitize the string by converting HTML characters to their HTML entities.
	 *
	 * Usage: '<index>' => 'htmlencode'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_htmlencode($value, $params = null) {
		return filter_var($value, FILTER_SANITIZE_SPECIAL_CHARS);
	}

	/**
	 * Sanitize the string by removing illegal characters from emails.
	 *
	 * Usage: '<index>' => 'sanitize_email'
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_sanitize_email($value, $params = null) {
		return filter_var($value, FILTER_SANITIZE_EMAIL);
	}

	/**
	 * Sanitize the string by removing illegal characters from numbers.
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_sanitize_numbers($value, $params = null) {
		return filter_var($value, FILTER_SANITIZE_NUMBER_INT);
	}

	/**
	 * Filter out all HTML tags except the defined basic tags.
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_basic_tags($value, $params = null) {
		return strip_tags($value, self::$basic_tags);
	}

	/**
	 * Convert the provided numeric value to a whole number.
	 *
	 * @param string $value
	 * @param array $params
	 *
	 * @return string
	 */
	protected function filter_whole_number($value, $params = null) {
		return intval($value);
	}

	// ** ------------------------- Validators ------------------------------------ ** //


	/**
	 * Verify that a value is contained within the pre-defined value set.
	 *
	 * Usage: '<index>' => 'contains,value value value'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_contains($field, $input, $param = null) {
		if (!isset($input[$field])) {
			return;
		}

		$param = trim(strtolower($param));

		$value = trim(strtolower($input[$field]));

		if (preg_match_all('#\'(.+?)\'#', $param, $matches, PREG_PATTERN_ORDER)) {
			$param = $matches[1];
		} else {
			$param = explode(chr(32), $param);
		}

		if (in_array($value, $param)) { // valid, return nothing
			return;
		}

		return array(
			'field' => $field,
			'value' => $value,
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Verify that a value is contained within the pre-defined value set.
	 * OUTPUT: will NOT show the list of values.
	 *
	 * Usage: '<index>' => 'contains_list,value;value;value'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_contains_list($field, $input, $param = null) {
		$param = trim(strtolower($param));

		$value = trim(strtolower($input[$field]));

		$param = explode(';', $param);

		// consider: in_array(strtolower($value), array_map('strtolower', $param)

		if (in_array($value, $param)) { // valid, return nothing
			return;
		} else {
			return array(
				'field' => $field,
				'value' => $value,
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Verify that a value is NOT contained within the pre-defined value set.
	 * OUTPUT: will NOT show the list of values.
	 *
	 * Usage: '<index>' => 'doesnt_contain_list,value;value;value'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_doesnt_contain_list($field, $input, $param = null) {
		$param = trim(strtolower($param));

		$value = trim(strtolower($input[$field]));

		$param = explode(';', $param);

		if (!in_array($value, $param)) { // valid, return nothing
			return;
		} else {
			return array(
				'field' => $field,
				'value' => $value,
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Check if the specified key is present and not empty.
	 *
	 * Usage: '<index>' => 'required'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_required($field, $input, $param = null) {
		if (isset($input[$field]) && ($input[$field] === false || $input[$field] === 0 || $input[$field] === 0.0 || $input[$field] === '0' || !empty($input[$field]))) {
			return;
		}

		return array(
			'field' => $field,
			'value' => null,
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided email is valid.
	 *
	 * Usage: '<index>' => 'valid_email'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_valid_email($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!filter_var($input[$field], FILTER_VALIDATE_EMAIL)) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value length is less or equal to a specific value.
	 *
	 * Usage: '<index>' => 'max_len,240'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_max_len($field, $input, $param = null) {
		if (!isset($input[$field])) {
			return;
		}

		if (function_exists('mb_strlen')) {
			if (mb_strlen($input[$field]) <= (int)$param) {
				return;
			}
		} else {
			if (strlen($input[$field]) <= (int)$param) {
				return;
			}
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided value length is more or equal to a specific value.
	 *
	 * Usage: '<index>' => 'min_len,4'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_min_len($field, $input, $param = null) {
		if (!isset($input[$field])) {
			return;
		}

		if (function_exists('mb_strlen')) {
			if (mb_strlen($input[$field]) >= (int)$param) {
				return;
			}
		} else {
			if (strlen($input[$field]) >= (int)$param) {
				return;
			}
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided value length matches a specific value.
	 *
	 * Usage: '<index>' => 'exact_len,5'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_exact_len($field, $input, $param = null) {
		if (!isset($input[$field])) {
			return;
		}

		if (function_exists('mb_strlen')) {
			if (mb_strlen($input[$field]) == (int)$param) {
				return;
			}
		} else {
			if (strlen($input[$field]) == (int)$param) {
				return;
			}
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided value contains only alpha characters.
	 *
	 * Usage: '<index>' => 'alpha'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_alpha($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!preg_match('/^([a-zÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïðòóôõöùúûüýÿ])+$/i', $input[$field]) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value contains only alpha-numeric characters.
	 *
	 * Usage: '<index>' => 'alpha_numeric'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_alpha_numeric($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!preg_match('/^([a-z0-9ÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïðòóôõöùúûüýÿ])+$/i', $input[$field]) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value contains only alpha characters with dashed and underscores.
	 *
	 * Usage: '<index>' => 'alpha_dash'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_alpha_dash($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!preg_match('/^([a-z0-9ÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïðòóôõöùúûüýÿ_-])+$/i', $input[$field]) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value contains only alpha numeric characters with spaces.
	 *
	 * Usage: '<index>' => 'alpha_space'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_alpha_space($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!preg_match("/^([a-z0-9ÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïðòóôõöùúûüýÿ\s])+$/i", $input[$field]) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid number or numeric string.
	 *
	 * Usage: '<index>' => 'numeric'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_numeric($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!is_numeric($input[$field])) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid integer.
	 *
	 * Usage: '<index>' => 'integer'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_integer($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (filter_var($input[$field], FILTER_VALIDATE_INT) === false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a PHP accepted boolean.
	 *
	 * Usage: '<index>' => 'boolean'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_boolean($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field]) && $input[$field] !== 0) {
			return;
		}

		if ($input[$field] === true || $input[$field] === false) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided value is a valid float.
	 *
	 * Usage: '<index>' => 'float'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_float($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (filter_var($input[$field], FILTER_VALIDATE_FLOAT) === false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid URL.
	 *
	 * Usage: '<index>' => 'valid_url'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_valid_url($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!filter_var($input[$field], FILTER_VALIDATE_URL)) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if a URL exists & is accessible.
	 *
	 * Usage: '<index>' => 'url_exists'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_url_exists($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$url = parse_url(strtolower($input[$field]));

		if (isset($url['host'])) {
			$url = $url['host'];
		}

		if (function_exists('checkdnsrr')) {
			if (checkdnsrr($url) === false) {
				return array(
					'field' => $field,
					'value' => $input[$field],
					'rule' => __FUNCTION__,
					'param' => $param,
				);
			}
		} else {
			if (gethostbyname($url) == $url) {
				return array(
					'field' => $field,
					'value' => $input[$field],
					'rule' => __FUNCTION__,
					'param' => $param,
				);
			}
		}
	}

	/**
	 * Determine if the provided value is a valid IP address.
	 *
	 * Usage: '<index>' => 'valid_ip'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_valid_ip($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!filter_var($input[$field], FILTER_VALIDATE_IP) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid IPv4 address.
	 *
	 * Usage: '<index>' => 'valid_ipv4'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 *
	 * @see http://pastebin.com/UvUPPYK0
	 */

	/*
	 * What about private networks? http://en.wikipedia.org/wiki/Private_network
	 * What about loop-back address? 127.0.0.1
	 */
	protected function validate_valid_ipv4($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!filter_var($input[$field], FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
			// removed !== FALSE

			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid IPv6 address.
	 *
	 * Usage: '<index>' => 'valid_ipv6'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_valid_ipv6($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!filter_var($input[$field], FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the input is a valid credit card number.
	 *
	 * See: http://stackoverflow.com/questions/174730/what-is-the-best-way-to-validate-a-credit-card-in-php
	 * Usage: '<index>' => 'valid_cc'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_valid_cc($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$number = preg_replace('/\D/', '', $input[$field]);

		if (function_exists('mb_strlen')) {
			$number_length = mb_strlen($number);
		} else {
			$number_length = strlen($number);
		}

		$parity = $number_length % 2;

		$total = 0;

		for ($i = 0; $i < $number_length; ++$i) {
			$digit = $number[$i];

			if ($i % 2 == $parity) {
				$digit *= 2;

				if ($digit > 9) {
					$digit -= 9;
				}
			}

			$total += $digit;
		}

		if ($total % 10 == 0) {
			return; // Valid
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the input is a valid human name [Credits to http://github.com/ben-s].
	 *
	 * See: https://github.com/Wixel/GUMP/issues/5
	 * Usage: '<index>' => 'valid_name'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_valid_name($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!preg_match("/^([a-zÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïñðòóôõöùúûüýÿ '-])+$/i", $input[$field]) !== false) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided input is likely to be a street address using weak detection.
	 *
	 * Usage: '<index>' => 'street_address'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_street_address($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		// Theory: 1 number, 1 or more spaces, 1 or more words
		$hasLetter = preg_match('/[a-zA-Z]/', $input[$field]);
		$hasDigit = preg_match('/\d/', $input[$field]);
		$hasSpace = preg_match('/\s/', $input[$field]);

		$passes = $hasLetter && $hasDigit && $hasSpace;

		if (!$passes) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided value is a valid IBAN.
	 *
	 * Usage: '<index>' => 'iban'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_iban($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		static $character = array(
			'A' => 10, 'C' => 12, 'D' => 13, 'E' => 14, 'F' => 15, 'G' => 16,
			'H' => 17, 'I' => 18, 'J' => 19, 'K' => 20, 'L' => 21, 'M' => 22,
			'N' => 23, 'O' => 24, 'P' => 25, 'Q' => 26, 'R' => 27, 'S' => 28,
			'T' => 29, 'U' => 30, 'V' => 31, 'W' => 32, 'X' => 33, 'Y' => 34,
			'Z' => 35, 'B' => 11
		);

		if (!preg_match("/\A[A-Z]{2}\d{2} ?[A-Z\d]{4}( ?\d{4}){1,} ?\d{1,4}\z/", $input[$field])) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}

		$iban = str_replace(' ', '', $input[$field]);
		$iban = substr($iban, 4) . substr($iban, 0, 4);
		$iban = strtr($iban, $character);

		if (bcmod($iban, 97) != 1) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided input is a valid date (ISO 8601).
	 *
	 * Usage: '<index>' => 'date'
	 *
	 * @param string $field
	 * @param string $input date ('Y-m-d') or datetime ('Y-m-d H:i:s')
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_date($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$cdate1 = date('Y-m-d', strtotime($input[$field]));
		$cdate2 = date('Y-m-d H:i:s', strtotime($input[$field]));

		if ($cdate1 != $input[$field] && $cdate2 != $input[$field]) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided input meets age requirement (ISO 8601).
	 *
	 * Usage: '<index>' => 'min_age,13'
	 *
	 * @param string $field
	 * @param string $input date ('Y-m-d') or datetime ('Y-m-d H:i:s')
	 * @param string $param int
	 *
	 * @return mixed
	 */
	protected function validate_min_age($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$cdate1 = new \DateTime(date('Y-m-d', strtotime($input[$field])));
		$today = new \DateTime(date('d-m-Y'));

		$interval = $cdate1->diff($today);
		$age = $interval->y;

		if ($age <= $param) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided numeric value is lower or equal to a specific value.
	 *
	 * Usage: '<index>' => 'max_numeric,50'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_max_numeric($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (is_numeric($input[$field]) && is_numeric($param) && ($input[$field] <= $param)) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided numeric value is higher or equal to a specific value.
	 *
	 * Usage: '<index>' => 'min_numeric,1'
	 *
	 * @param string $field
	 * @param array $input
	 * @param null $param
	 *
	 * @return mixed
	 */
	protected function validate_min_numeric($field, $input, $param = null) {
		if (!isset($input[$field])) {
			return;
		}

		if (is_numeric($input[$field]) && is_numeric($param) && ($input[$field] >= $param)) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided value starts with param.
	 *
	 * Usage: '<index>' => 'starts,Z'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_starts($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (strpos($input[$field], $param) !== 0) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * checks if a file was uploaded.
	 *
	 * Usage: '<index>' => 'required_file'
	 *
	 * @param  string $field
	 * @param  array $input
	 *
	 * @return mixed
	 */
	protected function validate_required_file($field, $input, $param = null) {
		if ($input[$field]['error'] !== 4) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * check the uploaded file for extension
	 * for now checks onlt the ext should add mime type check.
	 *
	 * Usage: '<index>' => 'starts,Z'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_extension($field, $input, $param = null) {
		if ($input[$field]['error'] !== 4) {
			$param = trim(strtolower($param));
			$allowed_extensions = explode(';', $param);

			$path_info = pathinfo($input[$field]['name']);
			$extension = $path_info['extension'];

			if (in_array($extension, $allowed_extensions)) {
				return;
			}

			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Determine if the provided field value equals current field value.
	 *
	 * Usage: '<index>' => 'equalsfield,Z'
	 *
	 * @param string $field
	 * @param string $input
	 * @param string $param field to compare with
	 *
	 * @return mixed
	 */
	protected function validate_equalsfield($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if ($input[$field] == $input[$param]) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Determine if the provided field value is a valid GUID (v4)
	 *
	 * Usage: '<index>' => 'guidv4'
	 *
	 * @param string $field
	 * @param string $input
	 * @param string $param field to compare with
	 *
	 * @return mixed
	 */
	protected function validate_guidv4($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (preg_match("/\{?[A-Z0-9]{8}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{12}\}?$/", $input[$field])) {
			return;
		}

		return array(
			'field' => $field,
			'value' => $input[$field],
			'rule' => __FUNCTION__,
			'param' => $param,
		);
	}

	/**
	 * Trims whitespace only when the value is a scalar.
	 *
	 * @param mixed $value
	 *
	 * @return mixed
	 */
	private function trimScalar($value) {
		if (is_scalar($value)) {
			$value = trim($value);
		}

		return $value;
	}

	/**
	 * Determine if the provided value is a valid phone number.
	 *
	 * Usage: '<index>' => 'phone_number'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 *
	 * Examples:
	 *
	 *  555-555-5555: valid
	 *    5555425555: valid
	 *    555 555 5555: valid
	 *    1(519) 555-4444: valid
	 *    1 (519) 555-4422: valid
	 *    1-555-555-5555: valid
	 *    1-(555)-555-5555: valid
	 */
	protected function validate_phone_number($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$regex = '/^(\d[\s-]?)?[\(\[\s-]{0,2}?\d{3}[\)\]\s-]{0,2}?\d{3}[\s-]?\d{4}$/i';
		if (!preg_match($regex, $input[$field])) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Custom regex validator.
	 *
	 * Usage: '<index>' => 'regex&&&/regex/'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_regex($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		$regex = $param;
		if (!preg_match($regex, $input[$field])) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}

	/**
	 * Json validatior.
	 *
	 * Usage: '<index>' => 'valid_json_string'
	 *
	 * @param string $field
	 * @param array $input
	 *
	 * @return mixed
	 */
	protected function validate_valid_json_string($field, $input, $param = null) {
		if (!isset($input[$field]) || empty($input[$field])) {
			return;
		}

		if (!is_string($input[$field]) || !is_object(json_decode($input[$field]))) {
			return array(
				'field' => $field,
				'value' => $input[$field],
				'rule' => __FUNCTION__,
				'param' => $param,
			);
		}
	}
} // EOC
