Add GAN samples.

Reviewed in http://codereview.appspot.com/4867056/

Index: samples/gan/ccoffers/offers.py
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diff --git a/samples/gan/ccoffers/offers.py b/samples/gan/ccoffers/offers.py
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+#!/usr/bin/python2.4
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2011 Google Inc.
+
+"""Sample for retrieving credit-card offers from GAN."""
+
+__author__ = 'leadpipe@google.com (Luke Blanshard)'
+
+import gflags
+import httplib2
+import json
+import logging
+import os
+import stat
+import sys
+
+from django.conf import settings
+from django.template import Template, Context
+from django.template.loader import get_template
+
+from apiclient.discovery import build
+from oauth2client.file import Storage
+from oauth2client.client import OAuth2WebServerFlow
+from oauth2client.tools import run
+
+settings.configure(DEBUG=True, TEMPLATE_DEBUG=True,
+    TEMPLATE_DIRS=('.'))
+
+
+FLAGS = gflags.FLAGS
+
+# Set up a Flow object to be used if we need to authenticate. This
+# sample uses OAuth 2.0, and we set up the OAuth2WebServerFlow with
+# the information it needs to authenticate. Note that it is called
+# the Web Server Flow, but it can also handle the flow for native
+# applications <http://code.google.com/apis/accounts/docs/OAuth2.html#IA>
+# The client_id client_secret are copied from the API Access tab on
+# the Google APIs Console <http://code.google.com/apis/console>. When
+# creating credentials for this application be sure to choose an Application
+# type of "Installed application".
+FLOW = OAuth2WebServerFlow(
+    client_id='767567128246-ti2q06i1neqm5boe2m1pqdc2riivhk41.apps.googleusercontent.com',
+    client_secret='UtdXI8nKD2SEcQRLQDZPkGT9',
+    scope='https://www.googleapis.com/auth/gan.readonly',
+    user_agent='gan-ccoffers-sample/1.0')
+
+# The gflags module makes defining command-line options easy for
+# applications. Run this program with the '--help' argument to see
+# all the flags that it understands.
+gflags.DEFINE_enum('logging_level', 'DEBUG',
+    ['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'],
+    'Set the level of logging detail.')
+
+gflags.DEFINE_enum("output_type", 'STDOUT', ['BOTH', 'HTML', 'STDOUT'],
+                   'Set how to output the results received from the API')
+
+gflags.DEFINE_string('credentials_filename', 'offers.dat',
+                     'File to store credentials in', short_name='cf')
+
+gflags.DEFINE_multistring('advertiser', None,
+                          'If given, advertiser we should run as')
+
+
+def usage(argv):
+  print 'Usage: %s <publisher-id>\n%s' % (argv[0], FLAGS)
+  sys.exit(1)
+
+
+def main(argv):
+  # Let the gflags module process the command-line arguments
+  try:
+    argv = FLAGS(argv)
+  except gflags.FlagsError, e:
+    raise e
+    usage(argv)
+
+  if len(argv) != 2:
+    usage(argv)
+  publisher = argv[1]
+
+  # Set the logging according to the command-line flag
+  logging.getLogger().setLevel(getattr(logging, FLAGS.logging_level))
+
+  # If the Credentials don't exist or are invalid run through the native client
+  # flow. The Storage object will ensure that if successful the good
+  # Credentials will get written back to a file.
+  storage = Storage(FLAGS.credentials_filename)
+  credentials = storage.get()
+  if credentials is None or credentials.invalid:
+    credentials = run(FLOW, storage)
+
+  # Create an httplib2.Http object to handle our HTTP requests and authorize it
+  # with our good Credentials.
+  http = httplib2.Http()
+  http = credentials.authorize(http)
+
+  service = build('gan', 'v1beta1', http=http)
+
+  ccOffers = service.ccOffers()
+
+  # Retrieve the relevant offers.
+  list_call = ccOffers.list(publisher=publisher,
+  # TODO(leadpipe): add back when advertiser is repeated
+  # advertiser=FLAGS.advertiser,
+                            projection='full')
+  list = list_call.execute()
+  list['publisher'] = publisher
+
+  if FLAGS.output_type in ["BOTH", "HTML"]:
+    template = get_template('offers_template.html')
+    context = Context(list)
+
+    fname = '%s.html' % publisher
+    out = open(fname, 'w')
+    out.write(template.render(context).encode('UTF-8'))
+    os.fchmod(out.fileno(), stat.S_IROTH|stat.S_IRGRP|stat.S_IRUSR|stat.S_IWUSR)
+    out.close()
+
+    print 'Wrote %s' % fname
+
+  if FLAGS.output_type in ["BOTH", "STDOUT"]:
+    print json.dumps(list, sort_keys=True, indent=4)
+
+if __name__ == '__main__':
+  main(sys.argv)