From b08db0035e76cdcaecb8a9811566bb828044a215 Mon Sep 17 00:00:00 2001
From: Christophe Benz <christophe.benz@gmail.com>
Date: Fri, 26 Mar 2010 20:14:10 +0100
Subject: [PATCH] WIP: updatable

---
 weboob/backends/dlfp/backend.py      |  5 +--
 weboob/capabilities/messages.py      |  5 ++-
 weboob/capabilities/updatable.py     | 46 ++++++++++++++++++++++++++++
 weboob/frontends/dummy/scripts/dummy |  2 +-
 4 files changed, 52 insertions(+), 6 deletions(-)
 create mode 100644 weboob/capabilities/updatable.py

diff --git a/weboob/backends/dlfp/backend.py b/weboob/backends/dlfp/backend.py
index 97097146..f39223bb 100644
--- a/weboob/backends/dlfp/backend.py
+++ b/weboob/backends/dlfp/backend.py
@@ -20,9 +20,10 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
 from weboob.backend import Backend
 from weboob.capabilities.messages import ICapMessages, ICapMessagesReply, Message
+from weboob.capabilities.updatable import ICapUpdatable
 from feeds import ArticlesList
 
-class DLFPBackend(Backend, ICapMessages, ICapMessagesReply):
+class DLFPBackend(Backend, ICapMessages, ICapMessagesReply, ICapUpdatable):
     MAINTAINER = 'Romain Bignon'
     EMAIL = 'romain@peerfuse.org'
     VERSION = '1.0'
@@ -30,7 +31,7 @@ class DLFPBackend(Backend, ICapMessages, ICapMessagesReply):
     def __init__(self, weboob):
         Backend.__init__(self, weboob)
 
-    def iter_new_messages(self, thread=None):
+    def iter_messages(self):
         articles_list = ArticlesList('newspaper')
         for article in articles_list.iter_articles():
             yield Message('threadid', article._id, article.title, article.author, signature='Bite bite bite bite',
diff --git a/weboob/capabilities/messages.py b/weboob/capabilities/messages.py
index aad1a40b..f48f06cb 100644
--- a/weboob/capabilities/messages.py
+++ b/weboob/capabilities/messages.py
@@ -78,12 +78,11 @@ class Message:
         return result.encode('utf-8')
 
 class ICapMessages:
-    def iter_new_messages(self, thread=None):
+    def iter_messages(self):
         """
         Iterates on new messages from last time this function has been called.
 
-        @param thread [str]  if given, get new messages for a specific thread.
-        @return [list]  a list of Message objects.
+        @return [list]  Message objects
         """
         raise NotImplementedError()
 
diff --git a/weboob/capabilities/updatable.py b/weboob/capabilities/updatable.py
new file mode 100644
index 00000000..b0ef785d
--- /dev/null
+++ b/weboob/capabilities/updatable.py
@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+
+"""
+Copyright(C) 2010  Romain Bignon
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+"""
+
+
+class ICapUpdatable:
+    snapshots = {}
+
+    def take_snapshot(self, name, collection):
+        if name not in self.snapshots:
+            self.snapshots[name] = dict(original=set(collection))
+        elif 'original' in self.snapshots[name]:
+            if 'updated' in self.snapshots[name]:
+                self.snapshots[name]['original'] = self.snapshots[name]['updated']
+            self.snapshots[name]['updated'] = set(collection)
+
+    def iter_new_items(self, name):
+        """
+        Iterates on new items from last time this function has been called.
+
+        @param name [str]  name of the collection to iter
+        @return [iter]  new items
+        """
+        if name not in self.snapshots:
+            raise ValueError('"%s" has not been snapshot previously' % name)
+        elif 'original' not in self.snapshots[name] or 'updated' not in self.snapshots[name]:
+            raise ValueError('At least two snapshots are required to detect new items')
+        diff = self.snapshots[name]['updated'] - self.snapshots[name]['original']
+        for item in diff:
+            yield item
diff --git a/weboob/frontends/dummy/scripts/dummy b/weboob/frontends/dummy/scripts/dummy
index 4d3a4a95..8e0af547 100755
--- a/weboob/frontends/dummy/scripts/dummy
+++ b/weboob/frontends/dummy/scripts/dummy
@@ -35,7 +35,7 @@ class Application(BaseApplication):
             print '= Processing backend name = %s' % name
             if backend.has_caps(ICapMessages):
                 print '== Backend is ICapMessages => print its messages'
-                for message in backend.iter_new_messages():
+                for message in backend.iter_messages():
                     print '=== %s' % message
             if backend.has_caps(ICapMessagesReply):
                 print '== Backend is ICapMessagesReply => TODO'