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

// Import framework stuff
use Org\Mxchange\CoreFramework\Factory\ObjectFactory;
use Org\Mxchange\CoreFramework\Generic\FrameworkInterface;
use Org\Mxchange\CoreFramework\Helper\Template\HelpableTemplate;

/**
 * A solveable graphical code CAPTCHA
 *
 * @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 GraphicalCodeCaptcha extends BaseCaptcha implements SolveableCaptcha {
	/**
	 * Hash of the CAPTCHA string
	 */
	private $hashedString = '';

	/**
	 * Encrypted string
	 */
	private $encryptedString = '';

	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this captcha class
	 *
	 * @param	$helperInstance		An instance of a helper class
	 * @param	$extraInstance		An extra instance, just for better hash data
	 * @return	$captchaInstance	An instance of this captcha class
	 */
	public static final function createGraphicalCodeCaptcha (HelpableTemplate $helperInstance, FrameworkInterface $extraInstance = NULL) {
		// Get a new instance
		$captchaInstance = new GraphicalCodeCaptcha();

		// Set template instance
		$captchaInstance->setHelperInstance($helperInstance);

		// Initialize the RNG
		$captchaInstance->initializeRandomNumberGenerator($extraInstance);

		// Return the instance
		return $captchaInstance;
	}

	/**
	 * Initiates the CAPTCHA
	 *
	 * @return	void
	 */
	public function initiateCaptcha () {
		// Get total length
		$captchaLength = $this->getConfigInstance()->getConfigEntry('captcha_string_length');

		// Get max string length
		$strLength = $this->getConfigInstance()->getConfigEntry('random_string_length');

		// Calculate starting position based on random place
		$start = $this->getRngInstance()->randomNumber(0, ($strLength - $captchaLength));

		// Test it
		assert($start >= 0);

		// Generate a random string for confirmation
		$randomString = $this->getRngInstance()->randomString($strLength);

		// Encode the string with BASE64
		$base64String = base64_encode($randomString);

		// Make this string a bit more readable for humans
		$captchaString = substr($base64String, $start, $captchaLength);

		// Get all characters we want to replace
		$searchChars = $this->getConfigInstance()->getConfigEntry('captcha_search_chars');

		// Get fixed salt and use it as "replacement characters"
		$replaceChars = $this->getRngInstance()->getExtraSalt();

		// Remove any plus, equals or slashes
		for ($searchIdx = 0; $searchIdx < strlen($searchChars); $searchIdx++) {
			// Get search character
			$search = substr($searchChars, $searchIdx, 1);

			// Random array index
			$charIdx = $this->getRngInstance()->randomNumber(0, (strlen($replaceChars) - 1));

			// Get replacement
			$replace = substr($replaceChars, $charIdx, 1);

			// Replace character
			$captchaString = str_replace($search, $replace, $captchaString, $captchaLength);
		} // END - foreach

		// Get crypto instance
		$cryptoInstance = ObjectFactory::createObjectByConfiguredName('crypto_class');

		// Hash the CAPTCHA code for later comparison
		$this->hashedString = $cryptoInstance->hashString($captchaString);

		// Encrypt the string for later usage
		$this->encryptedString = $cryptoInstance->encryptString($captchaString);
	}

	/**
	 * Render the CAPTCHA code
	 *
	 * @return	void
	 */
	public function renderCode () {
		// Get helper instance
		$helperInstance = $this->getHelperInstance();

		// Get template instance
		$templateInstance = $helperInstance->getTemplateInstance();

		// Load a template for this CAPTCHA
		$templateInstance->loadCodeTemplate('captch_graphic_code');

		// Rename variable
		$templateInstance->renameVariable('captcha_code', $helperInstance->getFormName() . '_captcha');
		$templateInstance->renameVariable('captcha_hash', $helperInstance->getFormName() . '_hash');
		$templateInstance->renameVariable('encrypted_code', $helperInstance->getFormName() . '_encrypt');

		// Assign variables
		$templateInstance->assignVariable($helperInstance->getFormName() . '_encrypt', urlencode(base64_encode($this->encryptedString)));
		$templateInstance->assignVariable($helperInstance->getFormName() . '_hash', $this->hashedString);

		// Compile the template
		$templateInstance->compileTemplate();

		// Get the content back
		$this->addContent($templateInstance->getRawTemplateData());
	}

}