#!/usr/bin/env python
# 
# Copyright under GPLv3

'''A class the inherits everything from python-twitter and allows oauth based access

Requires:
  python-twitter
  simplejson
  oauth
'''

__author__ = "Hameedullah Khan <hameed@hameedkhan.net>"
__version__ = "0.1"


from twitter import Api, User
try:
    import json as simplejson
except:
    from django.utils import simplejson

from oauth import oauth



# Taken from oauth implementation at: http://github.com/harperreed/twitteroauth-python/tree/master
REQUEST_TOKEN_URL = 'https://twitter.com/oauth/request_token'
ACCESS_TOKEN_URL = 'https://twitter.com/oauth/access_token'
AUTHORIZATION_URL = 'http://twitter.com/oauth/authorize'
SIGNIN_URL = 'http://twitter.com/oauth/authenticate'


class OAuthApi(Api):
    def __init__(self, consumer_key, consumer_secret, access_token=None):
        if access_token:
            Api.__init__(self,access_token.key, access_token.secret)
        else:
            Api.__init__(self)
        self._Consumer = oauth.OAuthConsumer(consumer_key, consumer_secret)
        self._signature_method = oauth.OAuthSignatureMethod_HMAC_SHA1()
        self._access_token = access_token


    def _GetOpener(self):
        opener = self._urllib.build_opener()
        return opener

    def _FetchUrl(self,
                    url,
                    post_data=None,
                    parameters=None,
                    no_cache=None):
        '''Fetch a URL, optionally caching for a specified time.
    
        Args:
          url: The URL to retrieve
          post_data: 
            A dict of (str, unicode) key/value pairs.  If set, POST will be used.
          parameters:
            A dict whose key/value pairs should encoded and added 
            to the query string. [OPTIONAL]
          no_cache: If true, overrides the cache on the current request
    
        Returns:
          A string containing the body of the response.
        '''
        # Build the extra parameters dict
        extra_params = {}
        try:
            if self._default_params:
                extra_params.update(self._default_params)
        except AttributeError:
            pass
        if parameters:
            extra_params.update(parameters)
    
        # Add key/value parameters to the query string of the url
        #url = self._BuildUrl(url, extra_params=extra_params)
    
        if post_data:
            http_method = "POST"
            extra_params.update(post_data)
        else:
            http_method = "GET"
        
        req = self._makeOAuthRequest(url, parameters=extra_params, 
                                                    http_method=http_method)
        self._signRequest(req, self._signature_method)

        
        # Get a url opener that can handle Oauth basic auth
        opener = self._GetOpener()
        
        #encoded_post_data = self._EncodePostData(post_data)

        if post_data:
            encoded_post_data = req.to_postdata()
            url = req.get_normalized_http_url()
        else:
            url = req.to_url()
            encoded_post_data = ""
            
        no_cache=True
        # Open and return the URL immediately if we're not going to cache
        # OR we are posting data
        if encoded_post_data or no_cache:
            if encoded_post_data:
                url_data = opener.open(url, encoded_post_data).read()
            else:
                url_data = opener.open(url).read()
            opener.close()
        else:
            # Unique keys are a combination of the url and the username
            if self._username:
                key = self._username + ':' + url
            else:
                key = url
    
            # See if it has been cached before
            last_cached = self._cache.GetCachedTime(key)
    
            # If the cached version is outdated then fetch another and store it
            if not last_cached or time.time() >= last_cached + self._cache_timeout:
                url_data = opener.open(url).read()
                opener.close()
                self._cache.Set(key, url_data)
            else:
                url_data = self._cache.Get(key)
    
        # Always return the latest version
        return url_data
    
    def _makeOAuthRequest(self, url, token=None,
                                        parameters=None, http_method="GET"):
        '''Make a OAuth request from url and parameters
        
        Args:
          url: The Url to use for creating OAuth Request
          parameters:
             The URL parameters
          http_method:
             The HTTP method to use
        Returns:
          A OAauthRequest object
        '''
        if not token:
            token = self._access_token
        request = oauth.OAuthRequest.from_consumer_and_token(
                            self._Consumer, token=token, 
                            http_url=url, parameters=parameters, 
                            http_method=http_method)
        return request

    def _signRequest(self, req, signature_method=oauth.OAuthSignatureMethod_HMAC_SHA1()):
        '''Sign a request
        
        Reminder: Created this function so incase
        if I need to add anything to request before signing
        
        Args:
          req: The OAuth request created via _makeOAuthRequest
          signate_method:
             The oauth signature method to use
        '''
        req.sign_request(signature_method, self._Consumer, self._access_token)
    

    def getAuthorizationURL(self, token, url=AUTHORIZATION_URL, callback_url = None):
        '''Create a signed authorization URL
        
        Returns:
          A signed OAuthRequest authorization URL 
        '''
        if callback_url:
            parameters= {'oauth_callback':callback_url}
        else:
            parameters= {}
        req = self._makeOAuthRequest(url, token=token, parameters=parameters)
        self._signRequest(req)
        return req.to_url()

    def getSigninURL(self, token, url=SIGNIN_URL, callback_url = None):
        '''Create a signed Sign-in URL
        
        Returns:
          A signed OAuthRequest Sign-in URL 
        '''
        
        signin_url = self.getAuthorizationURL(token, url, callback_url)
        return signin_url
    
    def getAccessToken(self, url=ACCESS_TOKEN_URL):
        token = self._FetchUrl(url, no_cache=True)
        return oauth.OAuthToken.from_string(token) 

    def getRequestToken(self, url=REQUEST_TOKEN_URL):
        '''Get a Request Token from Twitter
        
        Returns:
          A OAuthToken object containing a request token
        '''
        resp = self._FetchUrl(url, no_cache=True)
        token = oauth.OAuthToken.from_string(resp)
        return token
    
    def GetUserInfo(self, url='https://twitter.com/account/verify_credentials.json'):
        '''Get user information from twitter
        
        Returns:
          Returns the twitter.User object
        '''
        json = self._FetchUrl(url)
        data = simplejson.loads(json)
        self._CheckForTwitterError(data)
        return User.NewFromJsonDict(data)
        
