<?php

/**
 * ownCloud
 *
 * @author Sam Tuke
 * @copyright 2012 Sam Tuke samtuke@owncloud.org
 *
 * 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 hook specific logic
 */

class Hooks {

	// TODO: use passphrase for encrypting private key that is separate to 
	// the login password

	/**
	 * @brief Startup encryption backend upon user login
	 * @note This method should never be called for users using client side encryption
	 */
	public static function login( $params ) {
	
		// Manually initialise Filesystem{} singleton with correct 
		// fake root path, in order to avoid fatal webdav errors
		\OC\Files\Filesystem::init( $params['uid'], '/' . 'files' . '/' );
	
		$view = new \OC_FilesystemView( '/' );

		$util = new Util( $view, $params['uid'] );
		
		// Check files_encryption infrastructure is ready for action
		if ( ! $util->ready() ) {
			
			\OC_Log::write( 'Encryption library', 'User account "' . $params['uid'] . '" is not ready for encryption; configuration started', \OC_Log::DEBUG );
			
			return $util->setupServerSide( $params['password'] );

		}
	
		\OC_FileProxy::$enabled = false;
		
		$encryptedKey = Keymanager::getPrivateKey( $view, $params['uid'] );
		
		\OC_FileProxy::$enabled = true;
		
		$privateKey = Crypt::symmetricDecryptFileContent( $encryptedKey, $params['password'] );
		
		$session = new Session( $view );
		
		$session->setPrivateKey( $privateKey, $params['uid'] );
		
		$view1 = new \OC_FilesystemView( '/' . $params['uid'] );
		
		// Set legacy encryption key if it exists, to support 
		// depreciated encryption system
		if ( 
			$view1->file_exists( 'encryption.key' )
			&& $encLegacyKey = $view1->file_get_contents( 'encryption.key' ) 
		) {
		
			$plainLegacyKey = Crypt::legacyDecrypt( $encLegacyKey, $params['password'] );
			
			$session->setLegacyKey( $plainLegacyKey );
		
		}
		
		\OC_FileProxy::$enabled = false;
		
		$publicKey = Keymanager::getPublicKey( $view, $params['uid'] );
		
		\OC_FileProxy::$enabled = false;
		
		// Encrypt existing user files:
		// This serves to upgrade old versions of the encryption
		// app (see appinfo/spec.txt)
		if ( 
			$util->encryptAll( $publicKey,  '/' . $params['uid'] . '/' . 'files', $session->getLegacyKey(), $params['password'] )
		) {
			
			\OC_Log::write( 
				'Encryption library', 'Encryption of existing files belonging to "' . $params['uid'] . '" started at login'
				, \OC_Log::INFO 
			);
		
		}

		return true;

	}
	
	/**
	 * @brief Change a user's encryption passphrase
	 * @param array $params keys: uid, password
	 */
	public static function setPassphrase( $params ) {
		
		// Only attempt to change passphrase if server-side encryption
		// is in use (client-side encryption does not have access to 
		// the necessary keys)
		if ( Crypt::mode() == 'server' ) {
			
			$session = new Session();
			
			// Get existing decrypted private key
			$privateKey = $session->getPrivateKey();
			
			// Encrypt private key with new user pwd as passphrase
			$encryptedPrivateKey = Crypt::symmetricEncryptFileContent( $privateKey, $params['password'] );
			
			// Save private key
			Keymanager::setPrivateKey( $encryptedPrivateKey );
			
			// NOTE: Session does not need to be updated as the 
			// private key has not changed, only the passphrase 
			// used to decrypt it has changed
			
		}
	
	}
	
	/**
	 * @brief update the encryption key of the file uploaded by the client
	 */
	public static function updateKeyfile( $params ) {
	
		if ( Crypt::mode() == 'client' ) {
			
			if ( isset( $params['properties']['key'] ) ) {
				
				$view = new \OC_FilesystemView( '/' );
				$userId = \OCP\User::getUser();
				
				Keymanager::setFileKey( $view, $params['path'], $userId, $params['properties']['key'] );
				
			} else {
				
				\OC_Log::write( 
					'Encryption library', "Client side encryption is enabled but the client doesn't provide a encryption key for the file!"
					, \OC_Log::ERROR 
				);
				
			}
			
		}
		
	}
	
	/**
	 * @brief 
	 */
	public static function postShared($params) {

		// NOTE: $params has keys:
		// [itemType] => file
		// itemSource -> int, filecache file ID
		// [parent] => 
		// [itemTarget] => /13
		// shareWith -> string, uid of user being shared to
		// fileTarget -> path of file being shared
		// uidOwner -> owner of the original file being shared
		// [shareType] => 0
		// [shareWith] => test1
		// [uidOwner] => admin
		// [permissions] => 17
		// [fileSource] => 13
		// [fileTarget] => /test8
		// [id] => 10
		// [token] =>
		// TODO: Should other kinds of item be encrypted too?
		if ($params['itemType'] === 'file' || $params['itemType'] === 'folder') {

			$view = new \OC_FilesystemView('/');
			$session = new Session($view);
			$userId = \OCP\User::getUser();
			$util = new Util($view, $userId);
			$path = $util->fileIdToPath($params['itemSource']);

			//check if this is a reshare action, that's true if the item source is already shared with me
			$sharedItem = \OCP\Share::getItemSharedWithBySource($params['itemType'], $params['itemSource']);
			if ($sharedItem) {
				// if it is a re-share than the file is located in my Shared folder
				$path = '/Shared'.$sharedItem['file_target'];
			} else {
				$path = $util->fileIdToPath($params['itemSource']);
			}

			$sharingEnabled = \OCP\Share::isEnabled();

			// if a folder was shared, get a list if all (sub-)folders
			if ($params['itemType'] === 'folder') {
				$allFiles = $util->getAllFiles($path);
			} else {
				$allFiles = array($path);
			}

			foreach ($allFiles as $path) {
				$usersSharing = $util->getSharingUsersArray($sharingEnabled, $path);

				$failed = array();

				// Attempt to set shareKey
				if (!$util->setSharedFileKeyfiles($session, $usersSharing, $path)) {

					$failed[] = $path;
				}
			}

			// If no attempts to set keyfiles failed
			if (empty($failed)) {

				return true;
			} else {

				return false;
			}
		}
	}
	
	/**
	 * @brief 
	 */
	public static function postUnshare( $params ) {
		
		// NOTE: $params has keys:
		// [itemType] => file
		// [itemSource] => 13
		// [shareType] => 0
		// [shareWith] => test1
	
		if ( $params['itemType'] === 'file' ||  $params['itemType'] === 'folder' ) {
		
			$view = new \OC_FilesystemView( '/' );
			$session = new Session($view);
			$userId = \OCP\User::getUser();
			$util = new Util( $view, $userId );
			$path = $util->fileIdToPath( $params['itemSource'] );

			// for group shares get a list of the group members
			if ($params['shareType'] == \OCP\Share::SHARE_TYPE_GROUP) {
				$userIds = \OC_Group::usersInGroup($params['shareWith']);
			} else {
				$userIds = array($params['shareWith']);
			}

			// if we unshare a folder we need a list of all (sub-)files
			if ($params['itemType'] === 'folder') {
				$allFiles = $util->getAllFiles($path);
			} else {
				$allFiles = array($path);
			}

			
			foreach ( $allFiles as $path ) {

				// check if the user still has access to the file, otherwise delete share key
				$sharingUsers = $util->getSharingUsersArray(true, $path);

				// Unshare every user who no longer has access to the file
				$delUsers = array_diff($userIds, $sharingUsers);
				if ( ! Keymanager::delShareKey( $view, $delUsers, $path ) ) {
				
					$failed[] = $path;
					
				}
				
			}
			
			// If no attempts to set keyfiles failed
			if ( empty( $failed ) ) {
			
				return true;
				
			} else {
			
				return false;
				
			}

		}

	}
	
	/**
	 * @brief 
	 */
	public static function postUnshareAll( $params ) {
	
		// NOTE: It appears that this is never called for files, so 
		// we may not need to implement it
		
	}
	
}