<?php
/**
 * A concrete filter for validating the username. This filter may intercept the
 * filter chain if no username is given or if the supplied username has an
 * invalid form. It could also intercept the filter chain if the username is
 * already taken.
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright(c) 2007, 2008 Roland Haeder, this is free software
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.ship-simu.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 UserNameValidatorFilter extends BaseFrameworkSystem implements Filterable {
	/**
	 * Private constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);

		// Set part description
		$this->setObjectDescription("A filter for username validation");

		// Create unique ID number
		$this->createUniqueID();

		// Clean up a little
		$this->removeNumberFormaters();
		$this->removeSystemArray();
	}

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

		// 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
	 */
	public function execute (Requestable $requestInstance, Responseable $responseInstance) {
		// Get username from request
		$userName = $requestInstance->getRequestElement('username');

		// Is the username set?
		if (is_null($userName)) {
			// Not found in form so stop the filtering process
			$requestInstance->requestIsValid(false);

			// Set a message for the response
			$responseInstance->addFatalMessage('username_unset');

			// Abort here
			return false;
		} elseif (empty($userName)) {
			// Empty field!
			$requestInstance->requestIsValid(false);

			// Set a message for the response
			$responseInstance->addFatalMessage('username_empty');

			// Abort here
			return false;
		} elseif ($this->ifUserNameIsTaken($userName)) {
			// Username is already taken
			$requestInstance->requestIsValid(false);

			// Set a message for the response
			$responseInstance->addFatalMessage('username_taken');

			// Abort here
			return false;
		}
	}

	/**
	 * Check wether the username as already been taken
	 *
	 * @param	$userName		Username to check for existence
	 * @return	$alreadyTaken	Wether the username has been taken
	 */
	private function ifUserNameIsTaken ($userName) {
		// Default is already taken
		$alreadyTaken = true;

		// Try to create a user instance
		try {
			// If this instance is created then the username *does* exist
			$userInstance = User::createUserByUsername($userName);
		} catch (UsernameMissingException $e) {
			// Okay, this user is missing!
			$alreadyTaken = false;
		}

		// Return the result
		return $alreadyTaken;
	}
}

// [EOF]
?>