Added support for token caching and refresh

spotipy/oauth2.py

@@ -1,8 +1,9 @@
 import base64
 import urllib
 import requests
-
-print ('oauth2 is here')
+import os
+import simplejson as json
+import time
 
 class SpotifyOauthError(Exception):
     pass
@@ -15,13 +16,39 @@ class SpotifyOAuth(object):
 
     OAUTH_AUTHORIZE_URL = 'https://accounts.spotify.com/authorize'
     OAUTH_TOKEN_URL = 'https://accounts.spotify.com/api/token'
-    def __init__(self, client_id, client_secret, redirect_uri, state=None, scope=None):
+
+    def __init__(self, client_id, client_secret, redirect_uri, state=None, scope=None, cache_path=None):
         self.client_id = client_id
         self.client_secret = client_secret
         self.redirect_uri = redirect_uri
         self.state=state
         self.scope=scope
+        self.cache_path = cache_path
+   
+    def get_cached_token(self):
+        token_info = None
+        if self.cache_path:
+            try:
+                f = open(self.cache_path)
+                token_info_string = f.read()
+                f.close()
+                token_info = json.loads(token_info_string)
+                if self.is_token_expired(token_info):
+                    new_token_info = self.refresh_access_token(token_info['refresh_token'])
+            except IOError:
+                pass
+        return token_info
 
+    def save_token_info(self, token_info):
+        if self.cache_path:
+            f = open(self.cache_path, 'w')
+            print >>f, json.dumps(token_info)
+            f.close()
+
+    def is_token_expired(self, token_info):
+        now = int(time.time())
+        return token_info['expires_at'] < now
+        
     def get_authorize_url(self):
         payload = {'client_id': self.client_id,
                    'response_type': 'code',
@@ -54,4 +81,23 @@ class SpotifyOAuth(object):
         response = requests.post(self.OAUTH_TOKEN_URL, data=payload, headers=headers, verify=True)
         if response.status_code is not 200:
             raise SpotifyOauthError(response.reason)
-        return response.json()['access_token']
+        token_info = response.json()
+        token_info['expires_at'] = int(time.time()) + token_info['expires_in']
+        self.save_token_info(token_info)
+        return token_info
+
+    def refresh_access_token(self, refresh_token):
+        payload = { 'refresh_token': refresh_token,
+                   'grant_type': 'refresh_token'}
+
+        auth_header = base64.b64encode(self.client_id + ':' + self.client_secret)
+        headers = {'Authorization': 'Basic %s' % auth_header}
+        response = requests.post(self.OAUTH_TOKEN_URL, data=payload, headers=headers, verify=True)
+        if response.status_code is not 200:
+            raise SpotifyOauthError(response.reason)
+        token_info = response.json()
+        token_info['expires_at'] = int(time.time()) + token_info['expires_in']
+        token_info['refresh_token'] = refresh_token
+        self.save_token_info(token_info)
+        return token_info
+