#!/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.

"""Helpers used to render response.
"""

__authors__ = [
  '"Todd Larsen" <tlarsen@google.com>',
  '"Pawel Solyga" <pawel.solyga@gmail.com>',
  ]


from google.appengine.api import users

from django import http
from django.template import loader

from soc import release
from soc.logic import accounts
from soc.logic import system
from soc.logic.models import site
from soc.views import helper
from soc.views.helper import redirects
from soc.views.helper import templates
from soc.views.sitemap import sidebar

import soc.logic
import soc.logic.models.user
import soc.views.helper.requests


def respond(request, template, context=None, response_args=None):
  """Helper to render a response, passing standard stuff to the response.

  Args:
    request: the Django HTTP request object
    template: the template (or search list of templates) to render
    context: the context supplied to the template (implements dict)
    response_args: keyword arguments passed to http.HttpResponse()
      (response_args['content'] is created with
      render_to_string(template, dictionary=context) if it is not present)

  Returns:
    django.shortcuts.render_to_response(template, context) results

  Raises:
    Any exceptions that django.template.loader.render_to_string() or
    django.http.HttpResponse() might raise.
  """

  if not context:
    context = getUniversalContext(request)

  if response_args is None:
    response_args = {}

  response_args['content'] = response_args.get(
      'content', loader.render_to_string(template, dictionary=context))
  return http.HttpResponse(**response_args)


def getUniversalContext(request):
  """Constructs a template context dict will many common variables defined.
  
  Args:
    request: the Django HTTP request object

  Returns:
    a new context dict containing:
    
    {
      'request': the Django HTTP request object passed in by the caller
      'account': the logged-in Google Account if there is one
      'user': the User entity corresponding to the Google Account in
        context['account']
      'is_admin': True if users.is_current_user_admin() is True
      'is_debug': True if system.isDebug() is True
      'sign_in': a Google Account login URL
      'sign_out': a Google Account logout URL
      'sidebar_menu_html': an HTML string that renders the sidebar menu
    }
  """

  account = users.get_current_user()

  context = {}
  context['request'] = request

  if account:
    context['account'] = account
    context['user'] = soc.logic.models.user.logic.getForFields(
        {'account': account}, unique=True)
    context['is_admin'] = accounts.isDeveloper(account=account)

  context['is_debug'] = system.isDebug()
  context['sign_in'] = users.create_login_url(request.path)
  context['sign_out'] = users.create_logout_url(request.path)
  context['sidebar_menu_items'] = sidebar.getSidebar(request)

  context['soc_release'] = release.RELEASE_TAG
  context['gae_version'] = system.getAppVersion()

  settings = site.logic.getFromFields(link_id=site.logic.DEF_SITE_LINK_ID)
  
  if settings:
    context['ga_tracking_num'] = settings.ga_tracking_num
 
  context['tos_link'] = getToSLink(settings)
 
  return context


def redirectToChangedSuffix(
    request, old_suffix, new_suffix=None, params=None):
  """Changes suffix of URL path and returns an HTTP redirect response.
  
  Args:
    request: the Django HTTP request object; redirect path is derived from
      request.path
    old_suffix, new_suffix, params:  see helper.requests.replaceSuffix()
      
  Returns:
    a Django HTTP redirect response pointing to the altered path.
  """
  path = helper.requests.replaceSuffix(request.path, old_suffix, new_suffix,
                                       params=params)
  return http.HttpResponseRedirect(path)


def errorResponse(error, request, template=None, context=None):
  """Creates an HTTP response from the soc.views.out_of_band.Error exception.

  Args:
    errror: a out_of_band.Error object
    request: a Django HTTP request
    template: the "sibling" template (or a search list of such templates)
      from which to construct the actual template name (or names)
    context: optional context dict supplied to the template, which is
      modified (so supply a copy if such modification is not acceptable)
  """
  if not context:
    context = error.context

  if not context:
    context = getUniversalContext(request)

  if not template:
    template = []

  # make a list of possible "sibling" templates, then append a default
  sibling_templates = templates.makeSiblingTemplatesList(template,
      error.TEMPLATE_NAME, default_template=error.DEF_TEMPLATE)

  context['status'] = error.response_args.get('status')

  if not context.get('message'):
    # supplied context did not explicitly override the message
    context['message'] = error.message_fmt % context

  return respond(request, sibling_templates, context=context,
                 response_args=error.response_args)

def getToSLink(presence):
  """Returns link to 'show' the ToS Document if it exists, None otherwise.

  Args:
    presence: Presence entity that may or may not have a tos property
  """
  if not presence:
    return None

  try:
    tos_doc = presence.tos
  except db.Error:
    return None

  if not tos_doc:
    return None

  return redirects.getPublicRedirect(tos_doc, {'url_name': 'document'})