#!/usr/bin/python2.5

#

# Copyright 2008 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.

"""Document (Model) query functions.

"""

__authors__ = [

  '"Pawel Solyga" <pawel.solyga@gmail.com>',

  ]

from google.appengine.ext import db

from soc.logic import key_name

import soc.models.document

import soc.logic.model

def getDocument(path, link_name):

  """Returns Document entity for a given path, or None if not found.  

  Args:

    path: a request path of the Document that uniquely identifies it

  """

  # lookup by Doc:path key name

  name = key_name.nameDocument(path, link_name)

  if name:

    document = soc.models.document.Document.get_by_key_name(name)

  else:

    document = None

  return document

def updateOrCreateDocument(path, **document_properties):

  """Update existing Document entity, or create new one with supplied properties.

  Args:

    path: a request path of the Document that uniquely identifies it

    **document_properties: keyword arguments that correspond to Document entity

      properties and their values

  Returns:

    the Document entity corresponding to the path, with any supplied

    properties changed, or a new Document entity now associated with the 

    supplied path and properties.

  """

  # attempt to retrieve the existing Document

  document = getDocument(path, document_properties['link_name'])

  if not document:

    # document did not exist, so create one in a transaction

    name = key_name.nameDocument(path, document_properties['link_name'])

    document = soc.models.document.Document.get_or_insert(

        name, **document_properties)

  # there is no way to be sure if get_or_insert() returned a new Document or

  # got an existing one due to a race, so update with document_properties anyway,

  # in a transaction

  return soc.logic.model.updateModelProperties(document, **document_properties)