main.py

"""A simple 'hello world' sample, which includes examples of start/stop
handlers, accesses the 'users' service, and shows how to get information about
the current instance.
"""

import logging
import os

import jinja2
import webapp2

from google.appengine.api import app_identity
from google.appengine.api import modules
from google.appengine.api import users

JINJA_ENVIRONMENT = jinja2.Environment(
    loader=jinja2.FileSystemLoader(os.path.dirname(__file__)),
    extensions=['jinja2.ext.autoescape'])


def get_url_for_instance(instance_id):
    """Return a full url of the current instance.
    Args:
        A string to represent an VM instance.
    Returns:
        URL string for the instance.
    """
    hostname = app_identity.get_default_version_hostname()
    return 'http://{}.{}.{}'.format(
        instance_id, modules.get_current_version_name(), hostname)


def get_signin_navigation(original_url):
    """Return a pair of a link text and a link for logging in/out.
    Args:
        An original URL.
    Returns:
        Two-value tuple; a url and a link text.
    """
    if users.get_current_user():
        url = users.create_logout_url(original_url)
        url_linktext = 'Logout'
    else:
        url = users.create_login_url(original_url)
        url_linktext = 'Login'
    return url, url_linktext


class Hello(webapp2.RequestHandler):
    """Display a greeting, using user info if logged in, and display information
    about the instance.
    """

    def get(self):
        """Display a 'Hello' message"""
        instance_id = modules.get_current_instance_id()
        message = 'Hello'
        if users.get_current_user():
            nick = users.get_current_user().nickname()
            message += ', %s' % nick
        template = JINJA_ENVIRONMENT.get_template('index.html')
        url, url_linktext = get_signin_navigation(self.request.uri)
        self.response.out.write(template.render(instance_url=get_url_for_instance(instance_id),
                                                url=url,
                                                url_linktext=url_linktext,
                                                message=message))


APPLICATION = webapp2.WSGIApplication([
    ('/', Hello)
], debug=True)