generalize keys_paginator and use it for Facebook

gratipay/elsewhere/_paginators.py

@@ -70,16 +70,18 @@ def f(self, response, parsed):
     return f
 
 
-def keys_paginator(**kw):
+def keys_paginator(page_key, **kw):
     # https://confluence.atlassian.com/display/BITBUCKET/Version+2#Version2-Pagingthroughobjectcollections
-    page_key = kw.get('page', 'values')
-    total_count_key = kw.get('total_count', 'size')
+    # https://developers.facebook.com/docs/graph-api/using-graph-api/v2.2#paging
+    paging_key = kw.get('paging')
+    total_key = kw.get('total')
     links_keys_map = tuple((k, kw.get(k, k)) for k in links_keys)
     def f(self, response, parsed):
         page = parsed[page_key]
-        links = {k: _strip_prefix(self.api_url, parsed[k2])
+        paging = parsed.get(paging_key, {}) if paging_key else parsed
+        links = {k: _strip_prefix(self.api_url, paging[k2])
                  for k, k2 in links_keys_map
-                 if parsed.get(k2)}
-        total_count = parsed.get(total_count_key, -1) if links else len(page)
+                 if paging.get(k2)}
+        total_count = paging.get(total_key, -1) if links else len(page)
         return page, total_count, links
     return f

gratipay/elsewhere/bitbucket.py

@@ -19,7 +19,7 @@ class Bitbucket(PlatformOAuth1):
 
     # API attributes
     api_format = 'json'
-    api_paginator = keys_paginator(prev='previous')
+    api_paginator = keys_paginator('values', prev='previous', total='size')
     api_url = 'https://bitbucket.org/api'
     api_user_info_path = '/2.0/users/{user_name}'
     api_user_self_info_path = '/2.0/user'

gratipay/elsewhere/facebook.py

@@ -2,6 +2,7 @@
 
 from gratipay.elsewhere import PlatformOAuth2
 from gratipay.elsewhere._extractors import key
+from gratipay.elsewhere._paginators import keys_paginator
 
 
 class Facebook(PlatformOAuth2):
@@ -18,6 +19,7 @@ class Facebook(PlatformOAuth2):
 
     # API attributes
     api_format = 'json'
+    api_paginator = keys_paginator('data', paging='paging', prev='previous')
     api_url = 'https://graph.facebook.com'
     api_user_info_path = '/{user_name}'
     api_user_self_info_path = '/me'