#

# Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

# All rights reserved.

# This component and the accompanying materials are made available

# under the terms of "Eclipse Public License v1.0"

# which accompanies this distribution, and is available

# at the URL "http://www.eclipse.org/legal/epl-v10.html".

#

# Initial Contributors:

# Nokia Corporation - initial contribution.

#

# Contributors:

#

# Description: 

#

import logging

import xml.parsers.expat

from cone.public import api, utils

from cone.storage import metadata

class StorageBase(api.Storage):

    """

    A general base class for all storage type classes

    """

    METADATA_FILENAME = ".metadata"

    def __init__(self,path):

        super(StorageBase, self).__init__(path)

        self.meta = self.read_metadata()

    def get_active_configuration(self): 

        """

        Return the active configuration. 

        If the storage holds only one configuration, it will be always active  

        """

        root_confmls = self.list_resources("/")

        root_confmls = utils.resourceref.filter_resources(root_confmls,"\.confml")

        if self.meta.get_root_file() == '' and len(root_confmls) == 1:

            return root_confmls[0]

        else:

            return self.meta.get_root_file()

    def set_active_configuration(self, ref):

        self.meta.set_root_file(ref)

    def read_metadata(self):

        meta = None

        if not self.is_resource(self.METADATA_FILENAME):

            logging.getLogger('cone').info("No metadata found for: %s" % (self.get_path()))

            # return empty metadata object

            meta = metadata.Metadata()

        else:

            res = self.open_resource(self.METADATA_FILENAME)

            try:

                try:

                    meta = metadata.MetadataReader().fromstring(res.read())

                except xml.parsers.expat.ExpatError:

                    """ in case of xml parsing error return empty metadata """

                    meta = metadata.Metadata()

            finally:

                res.close()

        return meta

    def write_metadata(self):

        # Try to update the metadata, which might fail on ZipStorage

        try:

            if self.get_mode(self.mode) != api.Storage.MODE_READ:

                # update the active configuration

                self.set_active_configuration(self.get_active_configuration())

                metares = self.open_resource(self.METADATA_FILENAME,"wb")

                metadata.MetadataWriter().toresource(self.meta,metares)

                metares.close()

        except Exception,e:

            logging.getLogger('cone').error("Could not save metadata. Exception %s" % e)

        return

    def close(self):

        if self.get_current_path() == "": 

            self.write_metadata()

        super(StorageBase, self).close()