<?php
// Own namespace
namespace Org\Mxchange\CoreFramework\Filter\Verifier\Captcha;

// Import framework stuff
use Org\Mxchange\CoreFramework\Factory\ObjectFactory;
use Org\Mxchange\CoreFramework\Filter\BaseFilter;
use Org\Mxchange\CoreFramework\Filter\Filterable;
use Org\Mxchange\CoreFramework\Request\Requestable;
use Org\Mxchange\CoreFramework\Response\Responseable;

/**
 * A concrete filter for validating code graphical CAPTCHAs with hashes
 *
 * @author		Roland Haeder <webmaster@shipsimu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2017 Core Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.shipsimu.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
class GraphicalCodeCaptchaVerifierFilter extends BaseFilter implements Filterable {
	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this filter class
	 *
	 * @return	$filterInstance		An instance of this filter class
	 */
	public static final function createGraphicalCodeCaptchaVerifierFilter () {
		// Get a new instance
		$filterInstance = new GraphicalCodeCaptchaVerifierFilter();

		// Return the instance
		return $filterInstance;
	}

	/**
	 * Executes the filter with given request and response objects
	 *
	 * @param	$requestInstance	An instance of a class with an Requestable interface
	 * @param	$responseInstance	An instance of a class with an Responseable interface
	 * @return	void
	 * @throws	FilterChainException	If this filter fails to operate
	 */
	public function execute (Requestable $requestInstance, Responseable $responseInstance) {
		// Is the form set?
		if (($requestInstance->getRequestElement('command') !== 'do_form') ||  (!$requestInstance->isRequestElementSet('form'))) {
			// Required field not set
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('command_form_invalid');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		} // END - if

		// Create config entry
		$configKey = sprintf('%s_captcha_secured',
			$requestInstance->getRequestElement('form')
		);

		// Is the CAPTCHA enabled?
		if ($this->getConfigInstance()->getConfigEntry($configKey) != 'Y') {
			// Not enabled, so don't check
			return;
		} // END - if

		// Get the captcha code
		$captchaCode = $requestInstance->getRequestElement('c_code');

		// Is this set?
		if (is_null($captchaCode)) {
			// Not set so request is invalid
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('captcha_code_unset');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		} elseif (empty($captchaCode)) {
			// Empty value so request is invalid
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('captcha_code_empty');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		}

		// Get the hash as well
		$captchaHash = $requestInstance->getRequestElement('hash');

		// Is this set?
		if (is_null($captchaHash)) {
			// Not set so request is invalid
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('captcha_hash_unset');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		} elseif (empty($captchaHash)) {
			// Empty value so request is invalid
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('captcha_hash_empty');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		}

		// Now, both are set hash the given one. First get a crypto instance
		$cryptoInstance = ObjectFactory::createObjectByConfiguredName('crypto_class');

		// Then hash the code
		$hashedCode = $cryptoInstance->hashString($captchaCode, $captchaHash);

		// Is this CAPTCHA valid?
		if ($hashedCode != $captchaHash) {
			// Not the same so request is invalid
			$requestInstance->requestIsValid(false);

			// Add fatal message
			$responseInstance->addFatalMessage('captcha_hash_mismatch');

			// Skip further processing
			throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
		} // END - not the same!
	}

}