Adding prompt_for_oauth to get a manager

Getting a manager for Spotipy instead of a single token so it can refresh.

spotipy/util.py

@@ -89,3 +89,87 @@ def prompt_for_user_token(username, scope=None, client_id = None,
         return token_info['access_token']
     else:
         return None
+
+
+def prompt_for_oauth_object(username, scope=None, client_id = None,
+        client_secret = None, redirect_uri = None):
+    ''' prompts the user to login if necessary and returns
+        the oauth object suitable for use with the spotipy.Spotify 
+        constructor
+
+        Parameters:
+
+         - username - the Spotify username
+         - scope - the desired scope of the request
+         - client_id - the client id of your app
+         - client_secret - the client secret of your app
+         - redirect_uri - the redirect URI of your app
+
+    '''
+
+    if not client_id:
+        client_id = os.getenv('SPOTIPY_CLIENT_ID')
+
+    if not client_secret:
+        client_secret = os.getenv('SPOTIPY_CLIENT_SECRET')
+
+    if not redirect_uri:
+        redirect_uri = os.getenv('SPOTIPY_REDIRECT_URI')
+
+    if not client_id:
+        print('''
+            You need to set your Spotify API credentials. You can do this by
+            setting environment variables like so:
+
+            export SPOTIPY_CLIENT_ID='your-spotify-client-id'
+            export SPOTIPY_CLIENT_SECRET='your-spotify-client-secret'
+            export SPOTIPY_REDIRECT_URI='your-app-redirect-url'
+
+            Get your credentials at     
+                https://developer.spotify.com/my-applications
+        ''')
+        raise spotipy.SpotifyException(550, -1, 'no credentials set')
+
+    sp_oauth = oauth2.SpotifyOAuth(client_id, client_secret, redirect_uri, 
+        scope=scope, cache_path=".cache-" + username )
+
+    # try to get a valid token for this user, from the cache,
+    # if not in the cache, the create a new (this will send
+    # the user to a web page where they can authorize this app)
+
+    token_info = sp_oauth.get_cached_token()
+
+    if not token_info:
+        print('''
+
+            User authentication requires interaction with your
+            web browser. Once you enter your credentials and
+            give authorization, you will be redirected to
+            a url.  Paste that url you were directed to to
+            complete the authorization.
+
+        ''')
+        auth_url = sp_oauth.get_authorize_url()
+        try:
+            webbrowser.open(auth_url)
+            print("Opened %s in your browser" % auth_url)
+        except:
+            print("Please navigate here: %s" % auth_url)
+
+        print()
+        print()
+        try:
+            response = raw_input("Enter the URL you were redirected to: ")
+        except NameError:
+            response = input("Enter the URL you were redirected to: ")
+
+        print()
+        print() 
+
+        code = sp_oauth.parse_response_code(response)
+        token_info = sp_oauth.get_access_token(code)
+    # Auth'ed API request
+    if token_info:
+        return sp_oauth
+    else:
+        return None