#!/usr/bin/python2.5

#

# Copyright 2009 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""The module which contains functions to manage tags in Melange.

"""

__authors__ = [

  '"Daniel Hans" <daniel.m.hans@gmail.com>',

]

class TagsService(object):

  """Helper class for tags corresponding to a model.

  """

  def __init__(self, tag_names):

    """Defines tag names.

    """

    self.tag_names = tag_names

  def prepareTagsForStoring(self, fields, scope):

    """For those fields which represent task values it prepares actual

    tag entries.

    Args:

      fields: a dict mapping tag names with values

      scope: scope for the tag that will be stored

    """

    for tag_name, tag_value in fields.iteritems():

      if tag_name in self.tag_names:

        fields[tag_name] = {'tags': tag_value, 'scope': scope}

  def setTagValuesForEntity(self, entity, fields):

    """Sets tag values for a particular entity based on fields dictionary.

    Args:

      entity: an entity which is to be tagged

      fields: a dict mapping tag names with values

    """

    if not entity:

      return None

    for tag_name, tag_value in fields.iteritems():

      if tag_name in self.tag_names:

        setattr(entity, tag_name, tag_value)

    return entity

  def removeAllTagsForEntity(self, entity):

    """Removes all tags defined for a particular entity.

    Args:

      entity: entity which the tags will be removed for

    """

    self.removeTagsForEntity(entity, self.tag_names)

  def removeTagsForEntity(self, entity, tag_names):

    """Removes all tags values for a particular entity based on tag_names

    list with name of the tags that are to be removed.

    Args:

      entity: entity which the tags will be removed for

      tag_names: list of tags to remove

    """

    if not entity:

      return

    for tag_name in tag_names:

        cls = entity.tags_class(tag_name)

        tags = cls.get_tags_for_key(entity.key())

        for tag in tags:

          tag.remove_tagged(entity.key())