#!/usr/bin/env python

#

# Copyright 2007 Google Inc.

#

# 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.

#

"""Convience functions for the Webapp framework."""

__all__ = ["login_required", "run_wsgi_app"]

import os

import sys

import wsgiref.util

from google.appengine.api import users

from google.appengine.ext import webapp

def login_required(handler_method):

  """A decorator to require that a user be logged in to access a handler.

  To use it, decorate your get() method like this:

    @login_required

    def get(self):

      user = users.GetCurrentUser(self)

      self.response.out.write('Hello, ' + user.nickname())

  We will redirect to a login page if the user is not logged in. We always

  redirect to the request URI, and Google Accounts only redirects back as a GET

  request, so this should not be used for POSTs.

  """

  def check_login(self, *args):

    if self.request.method != 'GET':

      raise webapp.Error('The check_login decorator can only be used for GET '

                         'requests')

    user = users.GetCurrentUser()

    if not user:

      self.redirect(users.CreateLoginURL(self.request.uri))

      return

    else:

      handler_method(self, *args)

  return check_login

def run_wsgi_app(application):

  """Runs your WSGI-compliant application object in a CGI environment.

  Compared to wsgiref.handlers.CGIHandler().run(application), this

  function takes some shortcuts.  Those are possible because the

  app server makes stronger promises than the CGI standard.

  """

  env = dict(os.environ)

  env["wsgi.input"] = sys.stdin

  env["wsgi.errors"] = sys.stderr

  env["wsgi.version"] = (1, 0)

  env["wsgi.run_once"] = True

  env["wsgi.url_scheme"] = wsgiref.util.guess_scheme(env)

  env["wsgi.multithread"] = False

  env["wsgi.multiprocess"] = False

  result = application(env, _start_response)

  if result is not None:

    for data in result:

      sys.stdout.write(data)

def _start_response(status, headers, exc_info=None):

  """A start_response() callable as specified by PEP 333"""

  if exc_info is not None:

    raise exc_info[0], exc_info[1], exc_info[2]

  print "Status: %s" % status

  for name, val in headers:

    print "%s: %s" % (name, val)

  print

  return sys.stdout.write