<?php

namespace Sabre\CalDAV\Backend;

use Sabre\VObject;
use Sabre\CalDAV;

/**
 * Abstract Calendaring backend. Extend this class to create your own backends.
 *
 * Checkout the BackendInterface for all the methods that must be implemented.
 *
 * @copyright Copyright (C) 2007-2015 fruux GmbH (https://fruux.com/).
 * @author Evert Pot (http://evertpot.com/)
 * @license http://sabre.io/license/ Modified BSD License
 */
abstract class AbstractBackend implements BackendInterface {

    /**
     * Updates properties for a calendar.
     *
     * The mutations array uses the propertyName in clark-notation as key,
     * and the array value for the property value. In the case a property
     * should be deleted, the property value will be null.
     *
     * This method must be atomic. If one property cannot be changed, the
     * entire operation must fail.
     *
     * If the operation was successful, true can be returned.
     * If the operation failed, false can be returned.
     *
     * Deletion of a non-existent property is always successful.
     *
     * Lastly, it is optional to return detailed information about any
     * failures. In this case an array should be returned with the following
     * structure:
     *
     * array(
     *   403 => array(
     *      '{DAV:}displayname' => null,
     *   ),
     *   424 => array(
     *      '{DAV:}owner' => null,
     *   )
     * )
     *
     * In this example it was forbidden to update {DAV:}displayname.
     * (403 Forbidden), which in turn also caused {DAV:}owner to fail
     * (424 Failed Dependency) because the request needs to be atomic.
     *
     * @param mixed $calendarId
     * @param array $mutations
     * @return bool|array
     */
    public function updateCalendar($calendarId, array $mutations) {

        return false;

    }

    /**
     * Performs a calendar-query on the contents of this calendar.
     *
     * The calendar-query is defined in RFC4791 : CalDAV. Using the
     * calendar-query it is possible for a client to request a specific set of
     * object, based on contents of iCalendar properties, date-ranges and
     * iCalendar component types (VTODO, VEVENT).
     *
     * This method should just return a list of (relative) urls that match this
     * query.
     *
     * The list of filters are specified as an array. The exact array is
     * documented by \Sabre\CalDAV\CalendarQueryParser.
     *
     * Note that it is extremely likely that getCalendarObject for every path
     * returned from this method will be called almost immediately after. You
     * may want to anticipate this to speed up these requests.
     *
     * This method provides a default implementation, which parses *all* the
     * iCalendar objects in the specified calendar.
     *
     * This default may well be good enough for personal use, and calendars
     * that aren't very large. But if you anticipate high usage, big calendars
     * or high loads, you are strongly adviced to optimize certain paths.
     *
     * The best way to do so is override this method and to optimize
     * specifically for 'common filters'.
     *
     * Requests that are extremely common are:
     *   * requests for just VEVENTS
     *   * requests for just VTODO
     *   * requests with a time-range-filter on either VEVENT or VTODO.
     *
     * ..and combinations of these requests. It may not be worth it to try to
     * handle every possible situation and just rely on the (relatively
     * easy to use) CalendarQueryValidator to handle the rest.
     *
     * Note that especially time-range-filters may be difficult to parse. A
     * time-range filter specified on a VEVENT must for instance also handle
     * recurrence rules correctly.
     * A good example of how to interprete all these filters can also simply
     * be found in \Sabre\CalDAV\CalendarQueryFilter. This class is as correct
     * as possible, so it gives you a good idea on what type of stuff you need
     * to think of.
     *
     * @param mixed $calendarId
     * @param array $filters
     * @return array
     */
    public function calendarQuery($calendarId, array $filters) {

        $result = array();
        $objects = $this->getCalendarObjects($calendarId);

        $validator = new \Sabre\CalDAV\CalendarQueryValidator();

        foreach($objects as $object) {

            if ($this->validateFilterForObject($object, $filters)) {
                $result[] = $object['uri'];
            }

        }

        return $result;

    }

    /**
     * This method validates if a filters (as passed to calendarQuery) matches
     * the given object.
     *
     * @param array $object
     * @param array $filters
     * @return bool
     */
    protected function validateFilterForObject(array $object, array $filters) {

        // Unfortunately, setting the 'calendardata' here is optional. If
        // it was excluded, we actually need another call to get this as
        // well.
        if (!isset($object['calendardata'])) {
            $object = $this->getCalendarObject($object['calendarid'], $object['uri']);
        }

        $data = is_resource($object['calendardata'])?stream_get_contents($object['calendardata']):$object['calendardata'];
        $vObject = VObject\Reader::read($data);

        $validator = new CalDAV\CalendarQueryValidator();
        return $validator->validate($vObject, $filters);

    }


}
