#!/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.

"""Views decorators.

"""

__authors__ = [

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

  '"Sverre Rabbelier" <sverre@rabbelier.nl>',

  ]

import logging

from functools import wraps

from google.appengine.runtime import DeadlineExceededError

from django import http

from soc.logic import dicts

class Error(Exception):

  pass

def view(func):

  """Decorator that insists that exceptions are handled by view.

  """

  @wraps(func)

  def view_wrapper(*args, **kwds):

    try:

      return func(*args, **kwds)

    except DeadlineExceededError:

      logging.exception('DeadlineExceededError')

      return http.HttpResponse('DeadlineExceededError')

    except MemoryError:

      logging.exception('MemoryError')

      return http.HttpResponse('MemoryError')

    except AssertionError:

      logging.exception('AssertionError')

      return http.HttpResponse('AssertionError')

  return view_wrapper

def merge_params(func):

  """Decorator that merges 'params' with self._params.

  """

  @wraps(func)

  def wrapper(self, *args, **kwargs):

    params = kwargs.get('params', {})

    kwargs['params'] = dicts.merge(params, self._params)

    return func(self, *args, **kwargs)

  return wrapper

def check_access(func):

  """This decorator does access checks for the specified view method.

  The rights dictionary is extracted from 'params', or, if either 'params' or

  'rights' do not exist, from self._params['rights'].

  """

  # Do not pollute helper.decorators with access specific imports

  from soc.views import out_of_band

  from soc.views import helper

  from soc.views.helper import access

  from soc.views.helper import responses

  @wraps(func)

  def wrapper(self, request, access_type, *args, **kwargs):

    params = kwargs.get('params', {})

    # Try to extract rights

    if 'rights' in params:

      rights = params['rights']

    else:

      rights = self._params['rights']

    check_kwargs = kwargs.copy()

    context = responses.getUniversalContext(request)

    id = context['account']

    user = context['user']

    check_kwargs['GET'] = request.GET

    check_kwargs['POST'] = request.POST

    check_kwargs['context'] = context

    # reset and pre-fill the Checker's cache

    rights.setCurrentUser(id, user)

    # Do the access check dance

    try:

      rights.checkAccess(access_type, check_kwargs)

    except out_of_band.Error, error:

      return helper.responses.errorResponse(error, request)

    return func(self, request, access_type, *args, **kwargs)

  return wrapper