<?php
/***********************************************
* File      :   backend.php
* Project   :   Z-Push
* Descr     :   This is what C++ people
*               (and PHP5) would call an
*               abstract class. The
*               backend module itself is
*               responsible for converting any
*               necessary types and formats.
*
*               If you wish to implement a new
*               backend, all you need to do is
*               to subclass the following class
*               (or implement an IBackend)
*               and place the subclassed file in
*               the backend/yourBackend directory. You can
*               then use your backend by
*               specifying it in the config.php file
*
* Created   :   01.10.2007
*
* Copyright 2007 - 2012 Zarafa Deutschland GmbH
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation with the following additional
* term according to sec. 7:
*
* According to sec. 7 of the GNU Affero General Public License, version 3,
* the terms of the AGPL are supplemented with the following terms:
*
* "Zarafa" is a registered trademark of Zarafa B.V.
* "Z-Push" is a registered trademark of Zarafa Deutschland GmbH
* The licensing of the Program under the AGPL does not imply a trademark license.
* Therefore any rights, title and interest in our trademarks remain entirely with us.
*
* However, if you propagate an unmodified version of the Program you are
* allowed to use the term "Z-Push" to indicate that you distribute the Program.
* Furthermore you may use our trademarks where it is necessary to indicate
* the intended purpose of a product or service provided you use it in accordance
* with honest practices in industrial or commercial matters.
* If you want to propagate modified versions of the Program under the name "Z-Push",
* you may only do so if you have a written permission by Zarafa Deutschland GmbH
* (to acquire a permission please contact Zarafa at trademark@zarafa.com).
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
* Consult LICENSE file for details
************************************************/

abstract class Backend implements IBackend {
    protected $permanentStorage;
    protected $stateStorage;

    /**
     * Constructor
     *
     * @access public
     */
    public function Backend() {
    }

    /**
     * Returns a IStateMachine implementation used to save states
     * The default StateMachine should be used here, so, false is fine
     *
     * @access public
     * @return boolean/object
     */
    public function GetStateMachine() {
        return false;
    }

    /**
     * Returns a ISearchProvider implementation used for searches
     * the SearchProvider is just a stub
     *
     * @access public
     * @return object       Implementation of ISearchProvider
     */
    public function GetSearchProvider() {
        return new SearchProvider();
    }

    /**
     * Indicates which AS version is supported by the backend.
     * By default AS version 2.5 (ASV_25) is returned (Z-Push 1 standard).
     * Subclasses can overwrite this method to set another AS version
     *
     * @access public
     * @return string       AS version constant
     */
    public function GetSupportedASVersion() {
        return ZPush::ASV_25;
    }

    /*********************************************************************
     * Methods to be implemented
     *
     * public function Logon($username, $domain, $password);
     * public function Setup($store, $checkACLonly = false, $folderid = false);
     * public function Logoff();
     * public function GetHierarchy();
     * public function GetImporter($folderid = false);
     * public function GetExporter($folderid = false);
     * public function SendMail($sm);
     * public function Fetch($folderid, $id, $contentparameters);
     * public function GetWasteBasket();
     * public function GetAttachmentData($attname);
     * public function MeetingResponse($requestid, $folderid, $response);
     *
     */

    /**
     * Deletes all contents of the specified folder.
     * This is generally used to empty the trash (wastebasked), but could also be used on any
     * other folder.
     *
     * @param string        $folderid
     * @param boolean       $includeSubfolders      (opt) also delete sub folders, default true
     *
     * @access public
     * @return boolean
     * @throws StatusException
     */
    public function EmptyFolder($folderid, $includeSubfolders = true) {
        return false;
    }

    /**
     * Indicates if the backend has a ChangesSink.
     * A sink is an active notification mechanism which does not need polling.
     *
     * @access public
     * @return boolean
     */
    public function HasChangesSink() {
        return false;
    }

    /**
     * The folder should be considered by the sink.
     * Folders which were not initialized should not result in a notification
     * of IBacken->ChangesSink().
     *
     * @param string        $folderid
     *
     * @access public
     * @return boolean      false if there is any problem with that folder
     */
     public function ChangesSinkInitialize($folderid) {
         return false;
     }

    /**
     * The actual ChangesSink.
     * For max. the $timeout value this method should block and if no changes
     * are available return an empty array.
     * If changes are available a list of folderids is expected.
     *
     * @param int           $timeout        max. amount of seconds to block
     *
     * @access public
     * @return array
     */
    public function ChangesSink($timeout = 30) {
        return array();
    }

    /**
     * Applies settings to and gets informations from the device
     *
     * @param SyncObject    $settings (SyncOOF or SyncUserInformation possible)
     *
     * @access public
     * @return SyncObject   $settings
     */
    public function Settings($settings) {
        if ($settings instanceof SyncOOF || $settings instanceof SyncUserInformation)
            $settings->Status = SYNC_SETTINGSSTATUS_SUCCESS;
        return $settings;
    }


    /**----------------------------------------------------------------------------------------------------------
     * Protected methods for BackendStorage
     *
     * Backends can use a permanent and a state related storage to save additional data
     * used during the synchronization.
     *
     * While permament storage is bound to the device and user, state related data works linked
     * to the regular states (and its counters).
     *
     * Both consist of a StateObject, while the backend can decide what to save in it.
     *
     * Before using $this->permanentStorage and $this->stateStorage the initilize methods have to be
     * called from the backend.
     *
     * Backend->LogOff() must call $this->SaveStorages() so the data is written to disk!
     *
     * These methods are an abstraction layer for StateManager->Get/SetBackendStorage()
     * which can also be used independently.
     */

    /**
     * Loads the permanent storage data of the user and device
     *
     * @access protected
     * @return
     */
    protected function InitializePermanentStorage() {
        if (!isset($this->permanentStorage)) {
            try {
                $this->permanentStorage = ZPush::GetDeviceManager()->GetStateManager()->GetBackendStorage(StateManager::BACKENDSTORAGE_PERMANENT);
            }
            catch (StateNotYetAvailableException $snyae) {
                $this->permanentStorage = new StateObject();
            }
            catch(StateNotFoundException $snfe) {
                $this->permanentStorage = new StateObject();
            }
        }
    }

   /**
     * Loads the state related storage data of the user and device
     * All data not necessary for the next state should be removed
     *
     * @access protected
     * @return
     */
    protected function InitializeStateStorage() {
        if (!isset($this->stateStorage)) {
            try {
                $this->stateStorage = ZPush::GetDeviceManager()->GetStateManager()->GetBackendStorage(StateManager::BACKENDSTORAGE_STATE);
            }
            catch (StateNotYetAvailableException $snyae) {
                $this->stateStorage = new StateObject();
            }
            catch(StateNotFoundException $snfe) {
                $this->stateStorage = new StateObject();
            }
        }
    }

   /**
     * Saves the permanent and state related storage data of the user and device
     * if they were loaded previousily
     * If the backend storage is used this should be called
     *
     * @access protected
     * @return
     */
    protected function SaveStorages() {
        if (isset($this->permanentStorage)) {
            try {
                ZPush::GetDeviceManager()->GetStateManager()->SetBackendStorage($this->permanentStorage, StateManager::BACKENDSTORAGE_PERMANENT);
            }
            catch (StateNotYetAvailableException $snyae) { }
            catch(StateNotFoundException $snfe) { }
        }
        if (isset($this->stateStorage)) {
            try {
                $this->storage_state = ZPush::GetDeviceManager()->GetStateManager()->SetBackendStorage($this->stateStorage, StateManager::BACKENDSTORAGE_STATE);
            }
            catch (StateNotYetAvailableException $snyae) { }
            catch(StateNotFoundException $snfe) { }
        }
    }

}
?>