<?php
  /**
   * ownCloud
   *
   * @author Sam Tuke
   * @copyright 2012 Sam Tuke samtuke@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 OCA\Encryption;
  
  /**
   * Class for handling encryption related session data
   */
  
  class Session {
  
  	private $view;

  	const NOT_INITIALIZED = '0';
  	const INIT_EXECUTED = '1';
  	const INIT_SUCCESSFUL = '2';

  	/**

  	 * if session is started, check if ownCloud key pair is set up, if not create it
  	 * @param \OC\Files\View $view

  	 *
  	 * @note The ownCloud key pair is used to allow public link sharing even if encryption is enabled
  	 */
  	public function __construct($view) {
  
  		$this->view = $view;
  
  		if (!$this->view->is_dir('owncloud_private_key')) {
  
  			$this->view->mkdir('owncloud_private_key');
  
  		}

  		$appConfig = \OC::$server->getAppConfig();
  
  		$publicShareKeyId = $appConfig->getValue('files_encryption', 'publicShareKeyId');

  
  		if ($publicShareKeyId === null) {
  			$publicShareKeyId = 'pubShare_' . substr(md5(time()), 0, 8);

  			$appConfig->setValue('files_encryption', 'publicShareKeyId', $publicShareKeyId);

  		}
  
  		if (
  			!$this->view->file_exists("/public-keys/" . $publicShareKeyId . ".public.key")
  			|| !$this->view->file_exists("/owncloud_private_key/" . $publicShareKeyId . ".private.key")
  		) {
  
  			$keypair = Crypt::createKeypair();
  
  			// Disable encryption proxy to prevent recursive calls
  			$proxyStatus = \OC_FileProxy::$enabled;
  			\OC_FileProxy::$enabled = false;
  
  			// Save public key
  
  			if (!$view->is_dir('/public-keys')) {
  				$view->mkdir('/public-keys');
  			}
  
  			$this->view->file_put_contents('/public-keys/' . $publicShareKeyId . '.public.key', $keypair['publicKey']);
  
  			// Encrypt private key empty passphrase

  			$cipher = \OCA\Encryption\Helper::getCipher();
  			$encryptedKey = \OCA\Encryption\Crypt::symmetricEncryptFileContent($keypair['privateKey'], '', $cipher);
  			if ($encryptedKey) {
  				Keymanager::setPrivateSystemKey($encryptedKey, $publicShareKeyId . '.private.key');
  			} else {
  				\OCP\Util::writeLog('files_encryption', 'Could not create public share keys', \OCP\Util::ERROR);
  			}

  
  			\OC_FileProxy::$enabled = $proxyStatus;
  
  		}
  
  		if (\OCA\Encryption\Helper::isPublicAccess()) {
  			// Disable encryption proxy to prevent recursive calls
  			$proxyStatus = \OC_FileProxy::$enabled;
  			\OC_FileProxy::$enabled = false;
  
  			$encryptedKey = $this->view->file_get_contents(
  				'/owncloud_private_key/' . $publicShareKeyId . '.private.key');

  			$privateKey = Crypt::decryptPrivateKey($encryptedKey, '');

  			$this->setPublicSharePrivateKey($privateKey);

  			$this->setInitialized(\OCA\Encryption\Session::INIT_SUCCESSFUL);

  			\OC_FileProxy::$enabled = $proxyStatus;
  		}
  	}
  
  	/**

  	 * Sets user private key to session

  	 * @param string $privateKey
  	 * @return bool
  	 *
  	 * @note this should only be set on login
  	 */
  	public function setPrivateKey($privateKey) {

  		\OC::$session->set('privateKey', $privateKey);

  
  		return true;
  
  	}
  
  	/**

  	 * remove keys from session
  	 */
  	public function removeKeys() {
  		\OC::$session->remove('publicSharePrivateKey');
  		\OC::$session->remove('privateKey');
  	}
  
  	/**

  	 * Sets status of encryption app
  	 * @param string $init INIT_SUCCESSFUL, INIT_EXECUTED, NOT_INITIALIZED

  	 * @return bool
  	 *
  	 * @note this doesn not indicate of the init was successful, we just remeber the try!
  	 */
  	public function setInitialized($init) {
  
  		\OC::$session->set('encryptionInitialized', $init);
  
  		return true;
  
  	}

  	/**

  	 * remove encryption keys and init status from session

  	 */
  	public function closeSession() {
  		\OC::$session->remove('encryptionInitialized');
  		\OC::$session->remove('privateKey');
  	}

  
  	/**

  	 * Gets status if we already tried to initialize the encryption app
  	 * @return string init status INIT_SUCCESSFUL, INIT_EXECUTED, NOT_INITIALIZED

  	 *
  	 * @note this doesn not indicate of the init was successful, we just remeber the try!
  	 */
  	public function getInitialized() {
  		if (!is_null(\OC::$session->get('encryptionInitialized'))) {
  			return \OC::$session->get('encryptionInitialized');
  		} else {
  			return self::NOT_INITIALIZED;
  		}
  	}
  
  	/**

  	 * Gets user or public share private key from session
  	 * @return string $privateKey The user's plaintext private key

  	 *
  	 */
  	public function getPrivateKey() {

  		// return the public share private key if this is a public access
  		if (\OCA\Encryption\Helper::isPublicAccess()) {
  			return $this->getPublicSharePrivateKey();
  		} else {

  			if (!is_null(\OC::$session->get('privateKey'))) {
  				return \OC::$session->get('privateKey');

  			} else {
  				return false;
  			}
  		}
  	}
  
  	/**

  	 * Sets public user private key to session

  	 * @param string $privateKey
  	 * @return bool
  	 */
  	public function setPublicSharePrivateKey($privateKey) {

  		\OC::$session->set('publicSharePrivateKey', $privateKey);

  
  		return true;
  
  	}
  
  	/**

  	 * Gets public share private key from session
  	 * @return string $privateKey

  	 *
  	 */
  	public function getPublicSharePrivateKey() {

  		if (!is_null(\OC::$session->get('publicSharePrivateKey'))) {
  			return \OC::$session->get('publicSharePrivateKey');

  		} else {
  			return false;
  		}

  	}
  
  
  	/**

  	 * Sets user legacy key to session
  	 * @param string $legacyKey

  	 * @return bool
  	 */
  	public function setLegacyKey($legacyKey) {

  		\OC::$session->set('legacyKey', $legacyKey);

  
  		return true;
  	}
  
  	/**

  	 * Gets user legacy key from session
  	 * @return string $legacyKey The user's plaintext legacy key

  	 *
  	 */
  	public function getLegacyKey() {

  		if (!is_null(\OC::$session->get('legacyKey'))) {

  			return \OC::$session->get('legacyKey');

  
  		} else {
  
  			return false;
  
  		}
  
  	}
  
  }