#!/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 google.appengine.runtime.apiproxy_errors import CapabilityDisabledError

from django import http

from django.utils.translation import ugettext

from soc.logic import dicts

from soc.views.helper import responses

DEF_DOWN_FOR_MAINTENANCE_MSG = ugettext("Down for maintenance")

DEF_IN_UNEXPECTED_MAINTENANCE_MSG = ugettext(

      "Down for unexpected maintenance.")

class Error(Exception):

  """Base class for all exceptions raised by this module.

  """

  pass

def maintenance(request):

  """Returns a 'down for maintenance' view.

  """

  context = responses.getUniversalContext(request)

  context['page_name'] = ugettext('Maintenance')

  notice = context.pop('site_notice')

  if not notice:

    context['body_content'] = DEF_IN_UNEXPECTED_MAINTENANCE_MSG

  else:

    context['body_content'] = notice

  context['header_title'] = DEF_DOWN_FOR_MAINTENANCE_MSG

  context['sidebar_menu_items'] = [

      {'heading': DEF_DOWN_FOR_MAINTENANCE_MSG,

       'group': ''},

      ]

  template = 'soc/base.html'

  return responses.respond(request, template, context=context)

def view(func):

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

  """

  from soc.views import out_of_band

  @wraps(func)

  def view_wrapper(request, *args, **kwds):

    """View decorator wrapper method.

    """

    context = responses.getUniversalContext(request)

    try:

      if not context['is_admin'] and context['in_maintenance']:

        return maintenance(request)

      return func(request, *args, **kwds)

    except CapabilityDisabledError, exception:

      logging.exception(exception)

      # assume the site is in maintenance if we get CDE

      return maintenance(request)

    except DeadlineExceededError, exception:

      template = 'soc/deadline_exceeded.html'

    except MemoryError, exception:

      template = 'soc/memory_error.html'

    except AssertionError, exception:

      template = 'soc/assertion_error.html'

    except out_of_band.Error, error:

      return responses.errorResponse(error, request)

    logging.exception(exception)

    return responses.respond(request, template, context=context)

  return view_wrapper

def merge_params(func):

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

  """

  @wraps(func)

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

    """Decorator wrapper method.

    """

    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 responses

  @wraps(func)

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

    """Decorator wrapper method.

    """

    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)

    responses.useJavaScript(context, self._params['js_uses_all'])

    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