#!/usr/bin/env python
#
# 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.

"""Tool to get an Access Token to access an auth protected Appengine end point.

This tool talks to the appengine end point, and gets an Access Token that is
stored in a file. This token can be used by a tool to do authorized access to
an appengine end point.
"""



from google.apputils import app
import gflags as flags
import httplib2
import oauth2 as oauth
import time

FLAGS = flags.FLAGS

flags.DEFINE_string(
        'appengine_host',
        None,
        'Appengine Host for whom we are trying to get an access token')
flags.DEFINE_string(
        'access_token_file',
        None,
        'The file where the access token is stored')


def get_access_token():
    if not FLAGS.appengine_host:
        print('must supply the appengine host')
        exit(1)

    # setup
    server = FLAGS.appengine_host
    request_token_url = server + '/_ah/OAuthGetRequestToken'
    authorization_url = server + '/_ah/OAuthAuthorizeToken'
    access_token_url = server + '/_ah/OAuthGetAccessToken'
    consumer = oauth.Consumer('anonymous', 'anonymous')
    signature_method_hmac_sha1 = oauth.SignatureMethod_HMAC_SHA1()

    # The Http client that will be used to make the requests.
    h = httplib2.Http()

    # get request token
    print '* Obtain a request token ...'
    parameters = {}
    # We dont have a callback server, we're going to use the browser to
    # authorize.

    #TODO: Add check for 401 etc
    parameters['oauth_callback'] = 'oob'
    oauth_req1 = oauth.Request.from_consumer_and_token(
        consumer, http_url=request_token_url, parameters=parameters)
    oauth_req1.sign_request(signature_method_hmac_sha1, consumer, None)
    print 'Request headers: %s' % str(oauth_req1.to_header())
    response, content = h.request(oauth_req1.to_url(), 'GET')
    token = oauth.Token.from_string(content)
    print 'GOT key: %s  secret:%s' % (str(token.key), str(token.secret))

    print '* Authorize the request token ...'
    oauth_req2 = oauth.Request.from_token_and_callback(
        token=token, callback='oob', http_url=authorization_url)
    print 'Please run this URL in a browser and paste the token back here'
    print oauth_req2.to_url()
    verification_code = raw_input('Enter verification code: ').strip()
    token.set_verifier(verification_code)

    # get access token
    print '* Obtain an access token ...'
    oauth_req3 = oauth.Request.from_consumer_and_token(
        consumer, token=token, http_url=access_token_url)
    oauth_req3.sign_request(signature_method_hmac_sha1, consumer, token)
    print 'Request headers: %s' % str(oauth_req3.to_header())
    response, content = h.request(oauth_req3.to_url(), 'GET')
    access_token = oauth.Token.from_string(content)
    print 'Access Token key: %s  secret:%s' % (str(access_token.key),
                                               str(access_token.secret))

    # Save the token to a file if its specified.
    if FLAGS.access_token_file:
        fhandle = open(FLAGS.access_token_file, 'w')
        fhandle.write(access_token.to_string())
        fhandle.close()

    # Example : access some protected resources
    print '* Checking the access token against protected resources...'
    # Assumes that the server + "/" is protected.
    test_url = server + "/"
    oauth_req4 = oauth.Request.from_consumer_and_token(consumer,
                                                       token=token,
                                                       http_url=test_url)
    oauth_req4.sign_request(signature_method_hmac_sha1, consumer, token)
    resp, content = h.request(test_url, "GET", headers=oauth_req4.to_header())
    print resp
    print content


def main(argv):
    get_access_token()

if __name__ == '__main__':
        app.run()