/**
* Actually write the resource to the database.  All checking of whether this is reasonable
* should be done before this is called.
* 
* @param DAVResource $resource The resource being written
* @param string $caldav_data The actual data to be written
* @param DAVResource $collection The collection containing the resource being written
* @param int $author The user_no who wants to put this resource on the server
* @param string $etag An etag unique for this event
* @param string $put_action_type INSERT or UPDATE depending on what we are to do
* @param boolean $caldav_context True, if we are responding via CalDAV, false for other ways of calling this
* @param string Either 'INSERT' or 'UPDATE': the type of action we are doing
* @param boolean $log_action Whether to log the fact that we are writing this into an action log (if configured)
* @param string $weak_etag An etag that is NOT modified on ATTENDEE changes for this event
* 
* @return boolean True for success, false for failure.
*/
function write_resource(DAVResource $resource, $caldav_data, DAVResource $collection, $author, &$etag, $put_action_type, $caldav_context, $log_action = true, $weak_etag = null)
{
    global $tz_regex, $session;
    $path = $resource->bound_from();
    $user_no = $collection->user_no();
    $vcal = new vCalendar($caldav_data);
    $resources = $vcal->GetComponents('VTIMEZONE', false);
    // Not matching VTIMEZONE
    if (!isset($resources[0])) {
        $resource_type = 'Unknown';
        /** @todo Handle writing non-calendar resources, like address book entries or random file data */
        rollback_on_error($caldav_context, $user_no, $path, translate('No calendar content'), 412);
        return false;
    } else {
        $first = $resources[0];
        if (!$first instanceof vComponent) {
            print $vcal->Render();
            fatal('This is not a vComponent!');
        }
        $resource_type = $first->GetType();
    }
    $collection_id = $collection->collection_id();
    $qry = new AwlQuery();
    $qry->Begin();
    $dav_params = array(':etag' => $etag, ':dav_data' => $caldav_data, ':caldav_type' => $resource_type, ':session_user' => $author, ':weak_etag' => $weak_etag);
    $calitem_params = array(':etag' => $etag);
    if ($put_action_type == 'INSERT') {
        $qry->QDo('SELECT nextval(\'dav_id_seq\') AS dav_id, null AS caldav_data');
    } else {
        $qry->QDo('SELECT dav_id, caldav_data FROM caldav_data WHERE dav_name = :dav_name ', array(':dav_name' => $path));
    }
    if ($qry->rows() != 1 || !($row = $qry->Fetch())) {
        // No dav_id?  => We're toast!
        trace_bug('No dav_id for "%s" on %s!!!', $path, $create_resource ? 'create' : 'update');
        rollback_on_error($caldav_context, $user_no, $path);
        return false;
    }
    $dav_id = $row->dav_id;
    $old_dav_data = $row->caldav_data;
    $dav_params[':dav_id'] = $dav_id;
    $calitem_params[':dav_id'] = $dav_id;
    $due = null;
    if ($first->GetType() == 'VTODO') {
        $due = $first->GetPValue('DUE');
    }
    $calitem_params[':due'] = $due;
    $dtstart = $first->GetPValue('DTSTART');
    if (empty($dtstart)) {
        $dtstart = $due;
    }
    $calitem_params[':dtstart'] = $dtstart;
    $dtend = $first->GetPValue('DTEND');
    if (isset($dtend) && $dtend != '') {
        dbg_error_log('PUT', ' DTEND: "%s", DTSTART: "%s", DURATION: "%s"', $dtend, $dtstart, $first->GetPValue('DURATION'));
        $calitem_params[':dtend'] = $dtend;
        $dtend = ':dtend';
    } else {
        // In this case we'll construct the SQL directly as a calculation relative to :dtstart
        $dtend = 'NULL';
        if ($first->GetPValue('DURATION') != '' and $dtstart != '') {
            $duration = trim(preg_replace('#[PT]#', ' ', $first->GetPValue('DURATION')));
            if ($duration == '') {
                $duration = '0 seconds';
            }
            $dtend = '(:dtstart::timestamp with time zone + :duration::interval)';
            $calitem_params[':duration'] = $duration;
        } elseif ($first->GetType() == 'VEVENT') {
            /**
             * From RFC2445 4.6.1:
             * For cases where a "VEVENT" calendar component specifies a "DTSTART"
             * property with a DATE data type but no "DTEND" property, the events
             * non-inclusive end is the end of the calendar date specified by the
             * "DTSTART" property. For cases where a "VEVENT" calendar component specifies
             * a "DTSTART" property with a DATE-TIME data type but no "DTEND" property,
             * the event ends on the same calendar date and time of day specified by the
             * "DTSTART" property.
             *
             * So we're looking for 'VALUE=DATE', to identify the duration, effectively.
             *
             */
            $dtstart_prop = $first->GetProperty('DTSTART');
            $value_type = $dtstart_prop->GetParameterValue('VALUE');
            dbg_error_log('PUT', 'DTSTART without DTEND. DTSTART value type is %s', $value_type);
            if (isset($value_type) && $value_type == 'DATE') {
                $dtend = '(:dtstart::timestamp with time zone::date + \'1 day\'::interval)';
            } else {
                $dtend = ':dtstart';
            }
        }
    }
    $dtstamp = $first->GetPValue('DTSTAMP');
    if (!isset($dtstamp) || $dtstamp == '') {
        // Strictly, we're dealing with an out of spec component here, but we'll try and survive
        $dtstamp = gmdate('Ymd\\THis\\Z');
    }
    $calitem_params[':dtstamp'] = $dtstamp;
    $last_modified = $first->GetPValue('LAST-MODIFIED');
    if (!isset($last_modified) || $last_modified == '') {
        $last_modified = $dtstamp;
    }
    $dav_params[':modified'] = $last_modified;
    $calitem_params[':modified'] = $last_modified;
    $created = $first->GetPValue('CREATED');
    if ($created == '00001231T000000Z') {
        $created = '20001231T000000Z';
    }
    $class = $first->GetPValue('CLASS');
    /* Check and see if we should over ride the class. */
    /** @todo is there some way we can move this out of this function? Or at least get rid of the need for the SQL query here. */
    if (public_events_only($user_no, $path)) {
        $class = 'PUBLIC';
    }
    /*
     * It seems that some calendar clients don't set a class...
     * RFC2445, 4.8.1.3:
     * Default is PUBLIC
     */
    if (!isset($class) || $class == '') {
        $class = 'PUBLIC';
    }
    $calitem_params[':class'] = $class;
    /** Calculate what timezone to set, first, if possible */
    $last_olson = 'Turkmenikikamukau';
    // I really hope this location doesn't exist!
    $tzid = GetTZID($first);
    if (!empty($tzid)) {
        $timezones = $vcal->GetComponents('VTIMEZONE');
        foreach ($timezones as $k => $tz) {
            if ($tz->GetPValue('TZID') != $tzid) {
                /**
                 * We'll skip any tz definitions that are for a TZID other than the DTSTART/DUE on the first VEVENT/VTODO 
                 */
                dbg_error_log('ERROR', ' Event uses TZID[%s], skipping included TZID[%s]!', $tz->GetPValue('TZID'), $tzid);
                continue;
            }
            $olson = olson_from_tzstring($tzid);
            if (empty($olson)) {
                $olson = $tz->GetPValue('X-LIC-LOCATION');
                if (!empty($olson)) {
                    $olson = olson_from_tzstring($olson);
                }
            }
        }
        dbg_error_log('PUT', ' Using TZID[%s] and location of [%s]', $tzid, isset($olson) ? $olson : '');
        if (!empty($olson) && $olson != $last_olson && preg_match($tz_regex, $olson)) {
            dbg_error_log('PUT', ' Setting timezone to %s', $olson);
            if ($olson != '') {
                $qry->QDo('SET TIMEZONE TO \'' . $olson . "'");
            }
            $last_olson = $olson;
        }
        $params = array(':tzid' => $tzid);
        $qry = new AwlQuery('SELECT 1 FROM timezones WHERE tzid = :tzid', $params);
        if ($qry->Exec('PUT', __LINE__, __FILE__) && $qry->rows() == 0) {
            $params[':olson_name'] = $olson;
            $params[':vtimezone'] = isset($tz) ? $tz->Render() : null;
            $qry->QDo('INSERT INTO timezones (tzid, olson_name, active, vtimezone) VALUES(:tzid,:olson_name,false,:vtimezone)', $params);
        }
        if (!isset($olson) || $olson == '') {
            $olson = $tzid;
        }
    }
    $qry->QDo('SELECT new_sync_token(0,' . $collection_id . ')');
    $calitem_params[':tzid'] = $tzid;
    $calitem_params[':uid'] = $first->GetPValue('UID');
    $calitem_params[':summary'] = $first->GetPValue('SUMMARY');
    $calitem_params[':location'] = $first->GetPValue('LOCATION');
    $calitem_params[':transp'] = $first->GetPValue('TRANSP');
    $calitem_params[':description'] = $first->GetPValue('DESCRIPTION');
    $calitem_params[':rrule'] = $first->GetPValue('RRULE');
    $calitem_params[':url'] = $first->GetPValue('URL');
    $calitem_params[':priority'] = $first->GetPValue('PRIORITY');
    $calitem_params[':percent_complete'] = $first->GetPValue('PERCENT-COMPLETE');
    $calitem_params[':status'] = $first->GetPValue('STATUS');
    if (!$collection->IsSchedulingCollection()) {
        if (do_scheduling_requests($vcal, $put_action_type == 'INSERT', $old_dav_data, true)) {
            $dav_params[':dav_data'] = $vcal->Render(null, true);
            $etag = null;
        }
    }
    if (!isset($dav_params[':modified'])) {
        $dav_params[':modified'] = 'now';
    }
    if ($put_action_type == 'INSERT') {
        $sql = 'INSERT INTO caldav_data ( dav_id, user_no, dav_name, dav_etag, caldav_data, caldav_type, logged_user, created, modified, collection_id, weak_etag )
            VALUES( :dav_id, :user_no, :dav_name, :etag, :dav_data, :caldav_type, :session_user, :created, :modified, :collection_id, :weak_etag )';
        $dav_params[':collection_id'] = $collection_id;
        $dav_params[':user_no'] = $user_no;
        $dav_params[':dav_name'] = $path;
        $dav_params[':created'] = isset($created) && $created != '' ? $created : $dtstamp;
    } else {
        $sql = 'UPDATE caldav_data SET caldav_data=:dav_data, dav_etag=:etag, caldav_type=:caldav_type, logged_user=:session_user,
            modified=:modified, weak_etag=:weak_etag WHERE dav_id=:dav_id';
    }
    $qry = new AwlQuery($sql, $dav_params);
    if (!$qry->Exec('PUT', __LINE__, __FILE__)) {
        fatal('Insert into calendar_item failed...');
        rollback_on_error($caldav_context, $user_no, $path);
        return false;
    }
    if ($put_action_type == 'INSERT') {
        $sql = <<<EOSQL
INSERT INTO calendar_item (user_no, dav_name, dav_id, dav_etag, uid, dtstamp,
                dtstart, dtend, summary, location, class, transp,
                description, rrule, tz_id, last_modified, url, priority,
                created, due, percent_complete, status, collection_id )
   VALUES ( :user_no, :dav_name, :dav_id, :etag, :uid, :dtstamp,
                :dtstart, {$dtend}, :summary, :location, :class, :transp,
                :description, :rrule, :tzid, :modified, :url, :priority,
                :created, :due, :percent_complete, :status, :collection_id )
EOSQL;
        $sync_change = 201;
        $calitem_params[':collection_id'] = $collection_id;
        $calitem_params[':user_no'] = $user_no;
        $calitem_params[':dav_name'] = $path;
        $calitem_params[':created'] = $dav_params[':created'];
    } else {
        $sql = <<<EOSQL
UPDATE calendar_item SET dav_etag=:etag, uid=:uid, dtstamp=:dtstamp,
                dtstart=:dtstart, dtend={$dtend}, summary=:summary, location=:location,
                class=:class, transp=:transp, description=:description, rrule=:rrule,
                tz_id=:tzid, last_modified=:modified, url=:url, priority=:priority,
                due=:due, percent_complete=:percent_complete, status=:status
       WHERE dav_id=:dav_id
EOSQL;
        $sync_change = 200;
    }
    write_alarms($dav_id, $first);
    write_attendees($dav_id, $vcal);
    if ($log_action && function_exists('log_caldav_action')) {
        log_caldav_action($put_action_type, $first->GetPValue('UID'), $user_no, $collection_id, $path);
    } else {
        if ($log_action) {
            dbg_error_log('PUT', 'No log_caldav_action( %s, %s, %s, %s, %s) can be called.', $put_action_type, $first->GetPValue('UID'), $user_no, $collection_id, $path);
        }
    }
    $qry = new AwlQuery($sql, $calitem_params);
    if (!$qry->Exec('PUT', __LINE__, __FILE__)) {
        rollback_on_error($caldav_context, $user_no, $path);
        return false;
    }
    $qry->QDo("SELECT write_sync_change( {$collection_id}, {$sync_change}, :dav_name)", array(':dav_name' => $path));
    $qry->Commit();
    if (function_exists('post_commit_action')) {
        post_commit_action($put_action_type, $first->GetPValue('UID'), $user_no, $collection_id, $path);
    }
    // Uncache anything to do with the collection
    $cache = getCacheInstance();
    $cache_ns = 'collection-' . preg_replace('{/[^/]*$}', '/', $path);
    $cache->delete($cache_ns, null);
    dbg_error_log('PUT', 'User: %d, ETag: %s, Path: %s', $author, $etag, $path);
    return true;
    // Success!
}
            $cache->delete('collection-' . $dav_resource->dav_name(), null);
            $request->DoResponse(204);
        }
    }
} else {
    if (isset($request->etag_if_match) && $request->etag_if_match != $dav_resource->unique_tag()) {
        $request->DoResponse(412, translate("Resource has changed on server - not deleted"));
    }
    // Check to see if we need to do any scheduling transactions for this one.
    do_scheduling_for_delete($dav_resource);
    // We need to serialise access to this process just for this collection
    $cache = getCacheInstance();
    $myLock = $cache->acquireLock('collection-' . $dav_resource->parent_path());
    $collection_id = $dav_resource->GetProperty('collection_id');
    $params = array(':dav_id' => $dav_resource->resource_id());
    if ($qry->QDo("DELETE FROM property WHERE dav_name = (SELECT dav_name FROM caldav_data WHERE dav_id = :dav_id)", $params) && $qry->QDo("DELETE FROM locks WHERE dav_name = (SELECT dav_name FROM caldav_data WHERE dav_id = :dav_id)", $params) && $qry->QDo("SELECT write_sync_change(collection_id, 404, caldav_data.dav_name) FROM caldav_data WHERE dav_id = :dav_id", $params) && $qry->QDo("DELETE FROM caldav_data WHERE dav_id = :dav_id", $params)) {
        if (function_exists('log_caldav_action')) {
            log_caldav_action('DELETE', $dav_resource->GetProperty('uid'), $dav_resource->GetProperty('user_no'), $collection_id, $request->path);
        }
        $qry->Commit();
        @dbg_error_log("DELETE", "DELETE: User: %d, ETag: %s, Path: %s", $session->user_no, $request->etag_if_match, $request->path);
        if (function_exists('post_commit_action')) {
            post_commit_action('DELETE', $dav_resource->GetProperty('uid'), $dav_resource->GetProperty('user_no'), $collection_id, $request->path);
        }
        $cache->delete('collection-' . $dav_resource->parent_path(), null);
        $cache->releaseLock($myLock);
        $request->DoResponse(204);
    }
    $cache->releaseLock($myLock);
}
$request->DoResponse(500);