#!/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.

"""RankerRoot (Model) query functions.

"""

__authors__ = [

  '"Lennard de Rijk" <ljvderijk@gmail.com>',

  ]

from google.appengine.api import datastore

from ranklist.ranker import Ranker

from soc.logic.models import base

import soc.models.ranker_root

class Logic(base.Logic):

  """Logic methods for the RankerRoot model.

  """

  def __init__(self, model=soc.models.ranker_root.RankerRoot, 

               base_model=None, scope_logic=None):

    """Defines the name, key_name and model for this entity.

    """

    super(Logic, self).__init__(model=model, base_model=base_model,

                                scope_logic=scope_logic)

  def create(self, name, scope, scores, branching_factor):

    """Creates a new RankerRoot with a new Ranker.

    Args:

      name: the Link ID of the ranker root

      scope: the entity owning the ranker

      score_range: A list showing the range of valid scores, in the form:

          [most_significant_score_min, most_significant_score_max,

          less_significant_score_min, less_significant_score_max, ...]

          Ranges are [inclusive, exclusive)

      branching_factor: The branching factor of the tree.  The number of

          datastore Gets is Theta(1/log(branching_factor)), and the amount of data

          returned by each Get is Theta(branching_factor). 

    """

    ranker = Ranker.Create(scores, branching_factor)

    fields = {'link_id': name,

        'scope': scope,

        'scope_path': scope.key().id_or_name(),

        'root': ranker.rootkey}

    key_name = self.getKeyNameFromFields(fields)

    self.updateOrCreateFromKeyName(fields, key_name)

  def getRootFromEntity(self, entity):

    """Returns a Ranker object created from a RankerRoot entity.

    Args:

      entity: A RankerRoot entity which the root should be retrieved of

    """

    return Ranker(datastore.Get(entity.key())['root'])

logic = Logic()