#!/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>',
  '"Sverre Rabbelier" <sverre@rabbelier.nl>',
  ]


from google.appengine.api import users

from django import http
from django.template import loader

from soc.logic import accounts
from soc.logic import system
from soc.logic.models import site
from soc.logic.models.user import logic as user_logic
from soc.modules import callback
from soc.views import helper
from soc.views.helper import redirects
from soc.views.helper import templates


def respond(request, template, context=None, response_args=None,
            response_headers=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)
    response_headers: optional dict containing HTTP response header names
      and corresponding values to set in the HttpResponse object before it
      is returned; default is None

  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:
    from soc.views.helper import params
    context = getUniversalContext(request)
    useJavaScript(context, params.DEF_JS_USES_LIST)

  if response_args is None:
    response_args = {}

  if 'content' not in response_args:
    content = loader.render_to_string(template, dictionary=context)
    response_args['content'] = content.strip('\n')

  http_response = http.HttpResponse(**response_args)

  if response_headers:
    for key, value in response_headers.iteritems():
      http_response[key] = value

  return http_response


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 = accounts.getCurrentAccount()
  user = None
  is_admin = False

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

  if account:
    user = user_logic.getForAccount(account)
    is_admin = user_logic.isDeveloper(account=account, user=user)

  context['account'] = account
  context['user'] = user
  context['is_admin'] = is_admin

  context['is_local'] = system.isLocal()
  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'] = callback.getCore().getSidebar(account, user)

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

  settings = site.logic.getSingleton()

  context['ga_tracking_num'] = settings.ga_tracking_num
  context['gmaps_api_key'] = settings.gmaps_api_key
  context['site_name'] = settings.site_name
  context['site_notice'] = settings.site_notice
  context['tos_link'] = redirects.getToSRedirect(settings)
 
  return context

def useJavaScript(context, uses):
  """Updates the context for JavaScript usage.
  """

  for use in uses:
    context['uses_%s' % use] = True

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:
    from soc.views.helper import params
    context = getUniversalContext(request)
    useJavaScript(context, params.DEF_JS_USES_LIST)

  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)